ISSN 1055- 1425
November 2007
This work was performed as part of the California PATH Program of the
University of California, in cooperation with the State of California Business,
Transportation, and Housing Agency, Department of Transportation, and the
United States Department of Transportation, Federal Highway Administration.
The contents of this report reflect the views of the authors who are responsible
for the facts and the accuracy of the data presented herein. The contents do not
necessarily reflect the official views or policies of the State of California. This
report does not constitute a standard, specification, or regulation.
Final Report for Task Order 5326/ 6326
CALIFORNIA PATH PROGRAM
INSTITUTE OF TRANSPORTATION STUDIES
UNIVERSITY OF CALIFORNIA, BERKELEY
Determining the Effectiveness
of HOV Lanes
UCB- ITS- PRR- 2007- 17
California PATH Research Report
Adolf D. May, Lannon Leiman, John Billheimer
University of California, Berkeley
CALIFORNIA PARTNERS FOR ADVANCED TRANSIT AND HIGHWAYS
i
ACKNOWLEDGMENTS
This document is the final report for a two- year PATH Project ( Task Orders 5326/ 6326).
Alexander Skabardonis served as the Principal Investigator.
The research team members would like to acknowledge the support given by Caltrans staff during
this two- year project, particularly Asfand Siddiqui the Caltrans Project Manager, of the Division
of Research and Innovation. Others in Caltrans that have been very helpful are:
Headquarters: Robert Ferwerda
Tim Buchanan
Keri Elsberry Vidad
District 01: Tony Arseneau
District 02: Scott White
District 03: Mike Auslam
District 04: David Seriani
Lance Hall
District 05: Claudia Espino
John Fouche
District 06: Pedro Ramirez
District 07: Marco Ruano
Dawn Helou
District 08: Tom Ainsworth
District 09: Brandon Fitt
District 10: Jim Ecclestone
District 11: Lou Melendez
Karen Wallace
George Mamaghani
District 12: Joe El Harake
Ed Khosravi
Farid Nowshiravan
Thanks also to Rita Evans and Seyem Petrites of the UC Berkeley Transportation Library for
their assistance during the literature searches, and to Gabriel Gomes, PATH postdoctoral
researcher, for helping to assemble the data for the I- 210 FREQ data set and for providing data
from PeMS.
Special thanks to Dilip Petel of the California Air Resources Board for his guidance during the
development of the Air Quality Module for FREQ and to Matt Barth, Konak Boriboonsomsin,
and Mike Todd of UC Riverside for their generosity in sharing their expertise in air quality
research and providing data from their CMEM emissions model.
The research team members would also like to acknowledge and thank Dave Schumacher, Chair
of the TRB Standing Committee on HOV Systems, for his support of this project.
ii
ABSTRACT
This document is the final report for the two- year PATH Project “ Determining the Effectiveness
of HOV Lanes”. It has been supported by the California Department of Transportation
( Caltrans). The primary objectives of this project have been to evaluate freeways having on-freeway
HOV lanes in terms of vehicle- travel, person- travel, occupancy distribution, shape and
duration of the peak period, congestion patterns, and air quality both in the HOV lane and the
adjacent mixed- flow lanes.
Based on a comprehensive literature review an extensive list of reference was developed, along
with summaries synthesizing the state of the knowledge regarding the effectiveness of HOV lanes
and their impact on air quality.
Historical and current field data were assembled and analyzed for all of California’s HOV lanes.
The analysis revealed that there is strong public support for HOV lanes, California’s HOV lanes
are well utilized and offer significant time savings to ride sharers, that there is a steady growth in
the number of carpoolers, violation rates are low, and that over time, HOV lanes cause carpools
to last longer.
The air quality module in the freeway simulation model FREQ was updated to reflect the most
up- to- date techniques for predicting air quality developed by the California Air Resources Board
in their EMFAC model. The new air quality methodology was also used to develop an off- line
air quality module for use with PeMS data.
The design of a successful HOV lane facility is a very difficult task and requires careful analyses
prior to implementation in order to move toward an optimum design. Accurate data on vehicle
occupancy distributions and traffic demand levels are essential for realistic modeling of such
facilities. To demonstrate the types of analyses that would be useful in this process, the modified
freeway simulation model FREQ was applied to two freeway study sites, one in Northern
California and one in Southern California. The FREQ model proved to be well suited for
investigating various combinations of HOV lane design and operating parameters. As traffic
demands increase and HOV lanes generate changes in ridesharing choices, the continued success
of HOV lane operation is likely to require changes in HOV lane design and operations. This will
require careful monitoring of the HOV lane facility and further modeling analyses.
Keywords: Computer Simulation, Emissions, Energy Consumption, Environmental Impact,
Environmental Impacts, Evaluation Models, Freeways, High Occupancy Vehicle Lanes, Policy,
Traffic Congestion, Traffic Control, Traffic Delay, Traffic Diversion, Traffic Flow, Traffic
Demand Management, Travel Time
iii
EXECUTIVE SUMMARY
This report describes the findings of a two- year investigation of the effectiveness of California’s
HOV lanes undertaken for Caltrans by researchers at the University of California at Berkeley as
part of the California PATH Program. The investigation entailed a comprehensive literature
review, a detailed examination of historical and current field data, the updating of air quality
models, and the modeling of alternative design and operating options in Northern and Southern
California.
LITERATURE REVIEW
At the beginning of this investigation, a comprehensive literature review was conducted. An
extensive list of references was developed, along with summaries synthesizing the state of
knowledge regarding the effectiveness of HOV lanes and their impact on air quality. Additional
key references, which appeared in the literature after the initial search, were added during the
project.
ANALYSIS OF OPERATING DATA
Historical and current field data were assembled on all of California’s HOV lanes. Historical
trends were analyzed, current operations were documented, past programs were investigated,
operating personnel were interviewed, and public opinion polls were reviewed. This process led
to the following key findings:
• Strong Public Support. Carpoolers and non- carpoolers alike understand and strongly
support HOV lanes.
• Good Utilization and Time Savings. California’s HOV lanes are well utilized during
the peak periods and offer significant time savings to ride sharers, who realize an average
savings of 6.7 minutes per trip.
• Steady Growth. It takes time for carpoolers to make and maintain ridesharing
commitments. But in most cases on California’s freeways, the introduction of HOV
lanes has been followed by a gradual build- up of ridesharing and an increase in the life
span of carpooling and vanpooling arrangements.
• Carpool Composition. Most carpoolers ( roughly ninety percent) ride with family
members or coworkers. While regular carpooling arrangements are most common, at any
given time as many as 20% of the people in carpool lanes are infrequent users who share
rides roughly once every other month.
• Safety. There is not enough evidence to state whether HOV lanes increase or decrease
accidents when installed on mainline freeways. However, the installation of direct HOV-to-
HOV connectors has almost universally reduced nearby accident rates.
• Violation Rates. Violation rates in all Caltrans districts average 5.6%, well below the
ten percent level identified as a threshold for concern.
iv
• Do Measured Ridesharing Increases Reflect New or Diverted Carpools? As time
goes on, the question of whether the carpools added to the freeway mix were new or
diverted becomes less and less important. If new, they represented an immediate
improvement in the overall vehicle occupancy picture. If diverted, they filled space
reserved to reward ridesharing behavior and freed up the space they left to relieve the
congestion faced by non- carpoolers. Over time, there is evidence that the HOV lanes
cause carpools to last longer, regardless of how they came to be in the lanes.
MODELING AIR QUALITY
The FREQ model was modified to reflect the most up- to- date techniques for predicting vehicle
emissions developed by the California Air Resources Board in their EMFAC model. The updated
methodology was developed, tested, and successfully demonstrated in a FREQ analysis of two
California freeways and as an off- line module manipulating freeway performance data from
surveillance detectors stored by PeMS ( Performance Measurement System).
ALTERNATIVES ANALYSIS
The updated FREQ model was used to demonstrate the analysis of the following policy and
design options on two California freeways under changing demand and ridesharing conditions:
• 3+ and 2+ carpool lane additions on I- 580 in Northern California; and
• Limited HOV lane access on I- 210 in Southern California.
3+ vs. 2+ Operating Policies. The addition of a 3+ HOV lane on I- 580 under current demand
conditions resulted in traffic flows of 300 to 350 vehicles per hour in the HOV lane, leaving
considerable excess capacity for future growth. As demand and carpool levels increased, HOV
lane utilization also increased, rising to 500- 550 vehicles per hour, and congestion developed in
the non- HOV lanes, raising the speed differential between HOV lanes and non- HOV lanes
increased from 4 mph to 22 mph. The predicted results indicated a significant reduction in total
travel time, an increase in vehicle- miles served, and no change in fuel consumptions rates nor
vehicle emission rates.
If the occupancy requirements of the new HOV lane are changed to 2+, increases in demand
quickly congest the HOV lanes, causing the speed differential between HOV and non- HOV lanes
to drop. As a result, the “ window of opportunity” when the system might benefit from the
addition of a 2+ HOV lane was relatively small. This window opened when traffic demand was
heavy and there were relatively low percentages of HOV vehicles, or when some 2+ vehicles
decided not to use the HOV lane. The operation with a 2+ HOV lane implementation can likely
be enhanced by introducing intermittent HOV lane barrier( s).
Intermittent HOV Lane Barrier Design. The quality of freeway performance with the existing
intermittent HOV lane barrier design depended upon the vehicle occupancy distribution and
unfortunately accurate data was not available. The best ‘ window of success’ occurred with
relative low percentage of 2+ vehicles ( 4% to 12%). Under higher percentages of 2+ vehicles,
the HOV lane was predicted to be congested.
In an attempt to extend the ‘ window of success’ to higher 2+ vehicle percentages, the existing
intermittent HOV lane barrier design was modified by reducing the number of access/ egress
v
points to the HOV lane. This more restricted intermittent HOV lane barrier design marginally
increased the ‘ window of success’ to higher 2+ vehicle percentages.
Analytic Conclusions. The design of a successful HOV lane facility is a very difficult task and
requires careful analyses prior to implementation in order to move toward an optimum design.
Accurate data on vehicle occupancy distributions and traffic demand levels are essential for the
realistic modeling of such facilities. As traffic demands increase and HOV lanes generate changes
in ridesharing choices, the continued success of HOV lane operations is likely to require changes
in HOV lane design and operations. This will require careful monitoring of the HOV lane facility
and further modeling analyses. The FREQ model proved to be well suited for investigating
various combinations of HOV lane design and operating parameters.
vi
TABLE OF CONTENTS
1. INTRODUCTION................................................................................................................... ........ 1- 1
1.1 OVERVIEW....................................................................................................................... ...... 1- 1
1.2 RESEARCH PLAN................................................................................................................... 1- 1
1.3 ORGANIZATION OF REPORT ............................................................................................. 1- 3
2. COMPREHENSIVE LITERATURE REVIEW AND SYNTHESSIS OF CURRENT
KNOWLEDGE ( TASK 1) ............................................................................................................. 2- 1
2.1 BACKGROUND..................................................................................................................... . 2- 1
2.2 OVERVIEW OF ACTIVITIES................................................................................................ 2- 1
2.3 SIGNIFICANT REFERENCES ............................................................................................... 2- 2
2.4 OTHER SELECTED RECENT REFERENCES .................................................................. 2- 13
2.4.1 California .................................................................................................................... 2- 13
2.4.2 Other States ................................................................................................................ 2- 14
2.4.3 Others......................................................................................................................... 2- 15
2.5 UPDATE OF LITERTURE REVIEW................................................................................... 2- 15
3. PERFORMANCE OF CALIFORNIA HOV LANES ( TASK 2)............................................. 3- 1
3.1 OVERVIEW....................................................................................................................... ...... 3- 1
3.2 DISTRICT THREE ................................................................................................................... 3- 2
3.2.1 System Map.................................................................................................................. 3- 2
3.2.2 HOV Freeway Inventory ............................................................................................. 3- 2
3.2.3 Historical System Performance................................................................................... 3- 4
3.2.4 Safety ............................................................................................................................ 3- 7
3.2.5 Current System Performance ...................................................................................... 3- 9
3.2.6 District Three Summary ............................................................................................ 3- 12
3.3 DISTRICT FOUR.................................................................................................................... 3- 13
3.3.1 System Map................................................................................................................ 3- 13
3.3.2 HOV Freeway Inventory ........................................................................................... 3- 13
3.3.3 Historical System Performance................................................................................. 3- 15
3.3.4 Current System Performance .................................................................................... 3- 19
3.3.5 Public Opinion ........................................................................................................... 3- 24
3.3.6 District Four Summary .............................................................................................. 3- 27
3.4 DISTRICT SEVEN ................................................................................................................. 3- 28
3.4.1 System Map................................................................................................................ 3- 28
3.4.2 HOV Freeway Inventory ........................................................................................... 3- 28
3.4.3 Historical System Performance ................................................................................ 3- 30
3.4.4 HOV Lane Safety Current System Performance ..................................................... 3- 32
vii
3.4.5 Current System Performance .................................................................................... 3- 33
3.4.6 Two Ground- Breaking Projects ................................................................................ 3- 36
3.4.7 Public Opinion ........................................................................................................... 3- 40
3.4.8 District Seven Summary............................................................................................ 3- 41
3.5 DISTRICT EIGHT .................................................................................................................. 3- 42
3.5.1 District Map................................................................................................................ 3- 42
3.5.2 HOV Freeway Inventory ........................................................................................... 3- 42
3.5.3 Historical System Performance................................................................................. 3- 44
3.5.4 HOV Lane Safety....................................................................................................... 3- 45
3.5.5 Current System Performance .................................................................................... 3- 47
3.5.6 District Eight Summary ............................................................................................. 3- 49
3.6 DISTRICT ELEVEN .............................................................................................................. 3- 51
3.6.1 System Map................................................................................................................ 3- 51
3.6.2 HOV Freeway Inventory ........................................................................................... 3- 51
3.6.3 Historical System Performance................................................................................. 3- 53
3.6.4 Current System Performance .................................................................................... 3- 56
3.6.5 Public Opinion ........................................................................................................... 3- 59
3.6.6 District Eleven Summary .......................................................................................... 3- 60
3.7 DISTRICT TWELVE.............................................................................................................. 3- 61
3.7.1 System Map................................................................................................................ 3- 61
3.7.2 HOV Freeway Inventory ........................................................................................... 3- 61
3.7.3 Historical System Performance................................................................................. 3- 63
3.7.4 HOV Lane Safety....................................................................................................... 3- 66
3.7.5 Current System Performance .................................................................................... 3- 72
3.7.6 Public Opinion ........................................................................................................... 3- 76
3.7.7 District Twelve Summary.......................................................................................... 3- 80
4. ASSESSMENT AND DEVELOPMENT OF METHODOLOGIES FOR ESTIMATING
AIR QUALITY ( TASK 3).............................................................................................................. 4- 1
4.1 FREQ AIR QUALITY MODULE ........................................................................................... 4- 1
4.1.1 Background .................................................................................................................. 4- 1
4.1.2 FREQ Air Quality Methodology................................................................................. 4- 1
4.1.2.1 Emissions from Vehicles on the Freeway and Arterial................................ 4- 2
4.1.2.2 Emissions from Delayed Vehicles ................................................................ 4- 2
4.2 HISTORY OF EMISSION RATES IN THE FREQ MODEL............................................... 4- 3
4.3 UPDATING THE EMISSION RATES IN THE FREQ MODEL......................................... 4- 5
4.3.1 Overview of the EMFAC2002 Model ........................................................................ 4- 6
4.3.2 Creating Correspondence Between Vehicle Classes in
EMFAC2002 and FREQ ............................................................................................. 4- 7
4.3.3 Determining the Parameters for the EMFAC2002 Runs........................................... 4- 9
4.3.4 Methodology for Converting EMFAC2002 Output Files to FREQ Tables ............. 4- 9
4.3.5 Modifying the FREQ Model ..................................................................................... 4- 15
4.4 EMISSION RATE TABLES FOR PEMS OFF- LINE AIR QUALITY MODOULE........ 4- 15
viii
5. APPLICATION OF MODIFIED FREQ MODEL TO EVALUATE
HOV LANES ( TASK 4) ................................................................................................................. 5- 1
5.1 INTRODUCTION................................................................................................................... . 5- 1
5.1.1 TASK 4 DESCRIPTION............................................................................................. 5- 1
5.1.2 SELECTION OF APPLICATION SITES ................................................................. 5- 1
5.1.3 CHAPTER ORGANIZATION................................................................................... 5- 2
5.2 DEMONSTRATION APPLICATION ON THE NORTHERN CALIFORNIA SITE ........ 5- 5
5.2.1 PREDICTED I- 580 FREEWAY PERFORMANCE UNDER 2004 TRAFFIC
CONDITIONS ............................................................................................................. 5- 5
5.2.2 HOV LANE DESIGN PARAMETERS AND THEIR SELECTION...................... 5- 9
5.2.2.1 Number of HOV Lanes .................................................................................. 5- 9
5.2.2.2 HOV Cut- Off Limits ...................................................................................... 5- 9
5.2.2.3 Length and Placement of HOV Lane ............................................................ 5- 9
5.2.2.4 Time of HOV Operations ............................................................................ 5- 10
5.2.2.5 HOV Barriers................................................................................................ 5- 10
5.2.2.6 Vehicle Occupancy Distribution ................................................................. 5- 10
5.2.2.7 Anticipated Future Growth .......................................................................... 5- 10
5.2.3 INVESTIGATION OF ADDED HOV LANE FOR 3+ VEHICLES..................... 5- 10
5.2.3.1 Effect of Adding the HOV Lane ................................................................. 5- 11
5.2.3.2 Sensitivity Analysis of Vehicle Occupancy Distribution and
Anticipated Future Growth....................................................................... 5- 11
5.2.3.3 Impact of 3+ HOV Lane with 0.95 Freeway Demand Level .................... 5- 11
5.2.3.4 Impact of 3+ HOV Lane with 1.00 Freeway Demand Level .................... 5- 12
5.2.3.5 Impact of 3+ HOV Lane with 1.05 Freeway Demand Level .................... 5- 12
5.2.3.6 Impact of 3+ HOV Lane with 1.10 Freeway Demand Level .................... 5- 12
5.2.3.7 Overall Summary of Results on Each Measure of Performance............... 5- 13
5.2.4 INVESTIGATION OF ADDED HOV LANE FOR 2+ VEHICLES..................... 5- 25
5.2.4.1 Effect of Adding the HOV Lane ................................................................. 5- 25
5.2.4.2 Sensitivity Analysis of Vehicle Occupancy Distribution and
Anticipated Future Growth....................................................................... 5- 25
5.2.4.3 Impact of 2+ HOV Lane with 0.95 Freeway Demand Level .................... 5- 26
5.2.4.4 Impact of 2+ HOV Lane with 1.00 Freeway Demand Level .................... 5- 26
5.2.4.5 Impact of 2+ HOV Lane with 1.05 Freeway Demand Level .................... 5- 27
5.2.4.6 Impact of 2+ HOV Lane with 1.10 Freeway Demand Level .................... 5- 27
5.2.4.7 Overall Summary of Results on Each Measure of Performance............... 5- 28
5.3 DEMONSTRATION APPLICATION ON THE SOUTHERN CALIFORNIA SITE....... 5- 40
5.3.1 SITE DESCRIPTION................................................................................................ 5- 40
5.3.2 DATA INPUT AND MODEL CALIBRATION..................................................... 5- 43
5.3.3 HOV LANE DESIGN PARAMETERS AND THEIR SELECTION.................... 5- 43
5.3.3.1 Number of HOV Lanes ................................................................................ 5- 44
5.3.3.2 HOV Cut- Off Limit...................................................................................... 5- 44
5.3.3.3 Length and Placement of HOV Lane .......................................................... 5- 44
5.3.3.4 Time of HOV Operations ............................................................................ 5- 44
5.3.3.5 HOV Barriers................................................................................................ 5- 44
5.3.3.6 Vehicle Occupancy Distribution ................................................................. 5- 44
5.3.3.7 Anticipated Future Growth .......................................................................... 5- 44
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5.3.4 PREDICTED I- 210 FREEWAY PERFORMANCE UNDER 2004 TRAFFIC
CONDITIONS ........................................................................................................... 5- 45
5.3.4.1 HOV Lane Traffic Performance.................................................................. 5- 45
5.3.4.2 Non- HOV Lane Traffic Performance ......................................................... 5- 45
5.3.5 INVESTIGATION OF ADDED HOV LANE FOR 2+ VEHICLES WITH
EXISTING HOV INTERMITTENT BARRIERS................................................... 5- 49
5.3.5.1 Sensitivity Analysis of Vehicle Occupation Distribution and
Anticipated Future Growth....................................................................... 5- 49
5.3.5.2 Impact of 2+ HOV Lane with 0.95 Freeway Demand Level .................... 5- 49
5.3.5.3 Impact of 2+ HOV Lane with 1.00 Freeway Demand Level .................... 5- 50
5.3.5.4 Impact of 2+ HOV Lane with 1.05 Freeway Demand Level .................... 5- 50
5.3.5.5 Impact of 2+ HOV Lane with 1.10 Freeway Demand Level .................... 5- 51
5.3.5.6 Overall Summary of Results on Each Measure of Performance............... 5- 51
5.3.6 INVESTIGATION OF MODIFIED HOV LANE FOR 2+ VEHICLES WITH
INCREASED HOV INTERMITTENT BARRIERS .............................................. 5- 62
5.3.6.1 Sensitivity Analysis of Vehicle Occupation Distribution and
Anticipated Future Growth....................................................................... 5- 63
5.3.6.2 Impact of 2+ HOV Lane with 0.95 Freeway Demand Level .................... 5- 63
5.3.6.3 Impact of 2+ HOV Lane with 1.00 Freeway Demand Level .................... 5- 64
5.3.6.4 Impact of 2+ HOV Lane with 1.05 Freeway Demand Level .................... 5- 64
5.3.6.5 Impact of 2+ HOV Lane with 1.10 Freeway Demand Level .................... 5- 65
5.3.6.6 Overall Summary of Results on Each Measure of Performance............... 5- 65
5.4 SUMMARY HIGHLIGHTS................................................................................................... 5- 76
5.4.1 I- 580 FREEWAY INVESTIGATION SUMMARY............................................... 5- 76
5.4.1.1 Highlights of 3+ HOV Added Lane ............................................................ 5- 76
5.4.1.2 Highlights of 2+ HOV Added Lane ............................................................ 5- 77
5.4.2 I- 210 FREEWAY INVESTIGATION SUMMARY............................................... 5- 78
5.4.2.1 Highlights of Partial Intermittent Barrier.................................................... 5- 78
5.4.2.2 Highlights of Reduced Partial Intermittent Barrier .................................... 5- 79
5.4.3 GENERAL SUMMARY HIGHLIGHTS................................................................. 5- 79
6. DEVELOPMENT OF OFF- LINE PeMS MODULE FOR
ESTIMATION AIR QUALITY ( TASK 5) .................................................................................. 6- 1
6.1 INTRODUCTION................................................................................................................... . 6- 1
6.1.1 Objective...................................................................................................................... 6- 1
6.1.2 The PeMS Software ..................................................................................................... 6- 1
6.1.3 Proposed Module Development.................................................................................. 6- 1
6.2 OVERVIEW....................................................................................................................... ...... 6- 1
6.3 COMPUTATION ISSUES ....................................................................................................... 6- 2
6.3.1 Sampling Rate .............................................................................................................. 6- 2
6.3.2 Vehicle Mix.................................................................................................................. 6- 3
6.3.3 Spacing of Detector Stations ....................................................................................... 6- 3
6.3.4 Data Quality ................................................................................................................. 6- 3
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6.4 DEMONSTRATION................................................................................................................. 6- 3
6.4.1 Location....................................................................................................................... 6- 3
6.4.2 Approach ...................................................................................................................... 6- 4
6.4.3 Single Segment Computations .................................................................................... 6- 4
6.4.4 Road Section Computations ........................................................................................ 6- 4
6.4.5 1- mph – 5- mph Comparison ....................................................................................... 6- 4
7. CONCLUSION..................................................................................................................... ........... 7- 1
7.1 OVERVIEW....................................................................................................................... ...... 7- 1
7.2 PERFORMANCE OF CALIFORNIA HOV LANES ............................................................ 7- 1
7.2.1 Historical Trends.......................................................................................................... 7- 1
7.2.2 Current performance .................................................................................................... 7- 5
7.2.3 Public Opinion ........................................................................................................... 7- 10
7.2.4 Key Findings .............................................................................................................. 7- 13
7.3 ASSESSING, DEVELOPING, AND DEMONSTRTING METHODS FOR
MODELING AIR QUALITY ................................................................................................ 7- 14
7.3.1 Model Development .................................................................................................. 7- 14
7.3.2 Model Testing and Demonstration............................................................................ 7- 15
7.4 FREQ ANALYTIC FINDINGS............................................................................................. 7- 18
7.4.1 I- 580 Analysis Results............................................................................................... 7- 18
7.4.2 I- 210 Analysis Results............................................................................................... 7- 19
7.4.3 Summary of FREQ Analysis Highlights .................................................................. 7- 20
8. REFERENCES..................................................................................................................... .......... R- 1
9. APPENDIX A ............................................................................................................................... .. A- 1
10. APPENDIX B.............................................................................................................................. ..... B- 1
11. APPENDIX C ............................................................................................................................... .. C- 1
12. APPENDIX D ............................................................................................................................... .. D- 1
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LIST OF FIGURES AND TABLES
CHAPTER THREE
3.1. HOV Lane Miles by District.......................................................................................................... 3- 1
3.2 District Three High Occupancy Vehicle Lanes ............................................................................ 3- 3
3.3 HOV Lane Traffic Over Time ( Veh/ Hr, SB PM) State Route 99: Caltrans District Three...... 3- 4
3.4 Percentage Of Carpool- Eligible Vehicles And Persons
Using State Route 99 During The Peak Morning And Evening Hours....................................... 3- 5
3.5 Travel Time Savings— SB PM On SR 99, Caltrans District Three............................................. 3- 6
3.6 Violation Rates Over Time State Route 99, Caltrans District Three .......................................... 3- 7
3.7 Accidents Per MVM On SR 99 ..................................................................................................... 3- 8
3.8 Peak Hour Vehicle Volumes, 2003/ 04, Caltrans District Three HOV Lanes............................. 3- 9
3.9 Percent Persons In HOV And Average Mixed- Flow Lanes
( 2003/ 04: Peak Hour, Peak Direction) ....................................................................................... 3- 10
3.10 HOV Lane Time Savings ( Peak Hour, Peak Direction),
Caltrans District Three HOV Lanes ............................................................................................ 3- 11
3.11 Violation Rates Per Lane, Caltrans District Three ( 2003/ 04).................................................... 3- 12
3.12 Map Of District Four HOV Freeway Lanes................................................................................ 3- 14
3.13 Vehicles/ Hour On All Bay Area HOV Lanes............................................................................. 3- 15
3.14 Percent Ridesharing Persons On Bay Area Bridges................................................................... 3- 16
3.15 Percent Carpool- Eligible Persons On Contra Costa County Freeways..................................... 3- 17
3.16 Ridesharing Over Time On Santa Clara County HOV Lanes ................................................... 3- 18
3.17 Peak Hour Vehicle Volumes, 2000 Caltrans District Four HOV Lanes ................................... 3- 19
3.18 Percent Persons In HOV And Average Mixed- Flow Lanes
( Caltrans District Four, 2003: Peak Hour, Peak Direction) ...................................................... 3- 20
3.19 Time Savings Per HOV Lane Mile, Caltrans District Four, 2003............................................. 3- 21
3.20 Violation Rates Per Lane, Caltrans District Four, 2003............................................................. 3- 22
3.21 Comparison Of Congestion Rates In Northern And Southern California................................. 3- 23
3.22 Estimated And Actual HOV Lane Time Savings ( 1997 Survey) ............................................. 3- 25
3.23 Map Of District Seven HOV Freeway Lanes ............................................................................. 3- 29
3.24 Carpools Over Time On HOV And Non- HOV Freeways
( Caltrans District Seven: Two Peak Morning Hours) ............................................................... 3- 30
3.25 Carpool Levels Before And After HOV Lane Introduction
( Caltrans District Seven: Peak Two Hours, AM and PM)........................................................ 3- 31
3.26 Average Vehicle Occupancy Across All Lanes.......................................................................... 3- 32
3.27 Peak Hour Vehicle Volumes, 2003 ............................................................................................. 3- 33
3.28 Percent Persons In HOV And Average Mixed- Flow Lanes
( Caltrans District Seven, 2003: Peak Hour, Peak Direction).................................................... 3- 34
3.29 HOV Lane Time Savings ( Caltrans District Seven: Peak Hour, Peak Direction) .................. 3- 35
3.30 Violation Rates Per Lane ( Caltrans District Seven, 2003)......................................................... 3- 36
3.31 Map Of District Eight HOV Freeway Lanes .............................................................................. 3- 43
3.32 Average Vehicle Occupancy Over Time ( Caltrans District Eight: 1999 TO 2005)............... 3- 44
3.33 Accident Rates On San Bernardino County Freeways With HOV Lanes ................................ 3- 45
3.34 Accident Rates On Riverside State Route 91 ............................................................................. 3- 46
3.35 Peak Hour Vehicle Volumes, 2005 ( Caltrans District Eight) ................................................... 3- 47
3.36 Percent Persons In HOV And Average Mixed- Flow Lanes
( Caltrans District Eight, 2005: Peak Hour, Peak Direction) ..................................................... 3- 48
3.37 Violation Rates Per Lane ( Caltrans District Eight, 2005)......................................................... 3- 49
xii
3.38 Map Of District Eleven HOV Freeway Lanes ............................................................................ 3- 52
3.39 Average Vehicle Occupancy Over Time. I- 15, Southbound AM ............................................ 3- 54
3.40 Average Occupancy Rates, I- 5/ 805 Merge, SR- 75, And SR- 54 ............................................... 3- 55
3.41 Peak Hour Vehicle Volumes ( Caltrans District Eleven, 2002) ................................................ 3- 56
3.42 Percent Persons In Average HOV And Mixed- Flow Lanes
( Caltrans District Eleven, 2002) .................................................................................................. 3- 57
3.43 Violation Rates Per Lane ( Caltrans District Eleven: 2002) ..................................................... 3- 58
3.44 Map Of District Twelve HOV Freeway Lanes........................................................................... 3- 62
3.45 Average Vehicle Occupancy Over Time, SR- 55 And I- 5, Orange County............................. 3- 64
3.46 Average Occupancy Rate Over Time, County I- 405 And SR- 91 ............................................. 3- 65
3.47 Travel Time Savings, SR- 55 Southbound, 7: 00 AM – 8 AM, 11.3 Miles ............................... 3- 66
3.48 SR- 55 Freeway Accident History............................................................................................... 3- 67
3.49 Accident Rates Per Million Vehicle- Miles,
I- 405 In Orange County Vs I- 405 In LA County ....................................................................... 3- 68
3.50 Accidents Per Million Vehicle Miles
State Route 57, SR- 22, I- 5 Interchange To Lambert Road........................................................ 3- 69
3.51 Accidents Per Million Vehicle Miles, I- 5 Segments In Orange County................................... 3- 70
3.52 Accident Rates Before And After The Opening
Of HOV- To- HOV Connectors In Caltrans District Twelve ...................................................... 3- 71
3.53 Peak Hour Vehicle Volumes, 2004 ............................................................................................. 3- 72
3.54 Percent Persons In HOV And Average Mixed- Flow Lanes
( Caltrans District Twelve, 2004: Peak Hour, Peak Direction) ................................................. 3- 73
3.55 HOV Lane Time Savings ( Caltrans District Twelve: Peak Hour, Peak Direction) ................. 3- 74
3.56 Violation Rates Per Lane ( Caltrans District Twelve, 2004) ..................................................... 3- 75
3.57 Support For Orange County HOV Lanes
( Answers to: “ Do you support or oppose having bus/ carpool lanes in
Southern California?” ................................................................................................................... 3- 77
3.58 Estimated And Actual HOV Lane Time Savings, Orange County HOV Lanes ...................... 3- 78
3.59 Self- Reported Impact Of HOV Lanes On Driving Patterns ...................................................... 3- 79
CHAPTER FOUR
4.1 Fleet Mix for Developing Emission Rates in FREQ Using EMFAC7 ( 1991) ........................... 4- 4
4.2. Emission Rates for California Vehicles, 1990 ( Hot Stabilized Conditions, Ambient
Temperature = 65o F)...................................................................................................................... 4- 5
4.3 Fleet Mix for Developing Emission Rates in FREQ Using EMFAC2002 ................................. 4- 8
4.4 Excerpt from EMFAC2002 Run – Part 1.................................................................................... 4- 11
4.4 Excerpt from EMFAC2002 Run – Part 2..................................................................................... 4- 12
4.5 Top Section of Worksheet for Calculating Total Hydrocarbon FREQ Emission Rate
Factors for Autos and Light Vehicles.......................................................................................... 4- 13
4.6 FREQ Emission Rate Factors Table for Total Hydrocarbons ................................................... 4- 14
4.7 Plots of the Vehicle Class for the FREQ Autos and Light Vehicle Class................................. 4- 15
CHAPTER FIVE
5.1. Candidate Sites for FREQ Applications............................................................................. 5- 3 to 5- 4
5.2. I- 580 Freeway Design Features ..................................................................................................... 5- 6
5.3. I- 580 Freeway Performance Without Added HOV Lane............................................................. 5- 7
5.4. I- 580 Freeway Congestion Pattern Without Added HOV Lane .................................................. 5- 8
xiii
5.5. Differential Effects of Performance Measures by Adding 3+ HOV Lane................................ 5- 16
5.6. Effect of Demand Growth and 3+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 0.95)........................................................................... 5- 17
5.7. Effect of Demand Growth and 3+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.00)........................................................................... 5- 18
5.8. Effect of Demand Growth and 3+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.05)........................................................................... 5- 19
5.9. Effect of Demand Growth and 3+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.10)........................................................................... 5- 20
5.10. Summary Effects of Demand Growth Level and 3+ Vehicle Percentages on
Performance of Full Length No Barrier HOV Lane...................................................... 5- 21 to 5- 24
5.11. Differential Effects of Performance Measures by Adding 2+ HOV Lane................................ 5- 31
5.12. Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 0.95)........................................................................... 5- 32
5.13. Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.00)........................................................................... 5- 33
5.14. Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.05)........................................................................... 5- 34
5.15 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Full Length No Barrier HOV Lane ( GF= 1.10)........................................................................... 5- 35
5.16 Summary Effects of Demand Growth Level and 2+ Vehicle Percentages on
Performance of Full Length No Barrier HOV Lane...................................................... 5- 36 to 5- 39
5.17 I- 210 Freeway Design Features ...................................................................................... 5- 41 to 5- 42
5.18 I- 210 Predicted HOV Lane Performance ................................................................................... 5- 46
5.19 I- 210 Predicted Non- HOV Lane Performance ........................................................................... 5- 47
5.20 I- 210 Non- HOV Lane Congestion Pattern.................................................................................. 5- 48
5.21 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier HOV Lane ( GF= 0.95).......................................................................................... 5- 54
5.22 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier HOV Lane ( GF= 1.00).......................................................................................... 5- 55
5.23 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier HOV Lane ( GF= 1.05).......................................................................................... 5- 56
5.24 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier HOV Lane ( GF= 1.10).......................................................................................... 5- 57
5.25 Summary Effects of Demand Growth Level and 2+ Vehicle Percentages on
Performance Partial Barrier HOV Lane ......................................................................... 5- 58 to 5- 61
5.26 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier and Reduced Partial Barrier HOV Lane ( GF= 0.95) .......................................... 5- 68
5.27 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier and Reduced Partial Barrier HOV Lane ( GF= 1.00) .......................................... 5- 69
5.28 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier and Reduced Partial Barrier HOV Lane ( GF= 1.05) .......................................... 5- 70
5.29 Effect of Demand Growth and 2+ Vehicle Percentages on Performance of
Partial Barrier and Reduced Partial Barrier HOV Lane ( GF= 1.10) .......................................... 5- 71
5.30 Summary Effects of Demand Growth Level and 2+ Vehicle Percentages on
Performance Partial Barrier and Reduced Partial Barrier HOV Lane.......................... 5- 72 to 5- 75
CHAPTER SIX
6.1 Overview of Computation Process ................................................................................................ 6- 6
xiv
6.2 Peak Hour Emissions At Fairoaks One Location ......................................................................... 6- 7
6.3 I- 210 West Peak Hour Emissions .................................................................................................. 6- 8
6.4 I- 210 W Peak Period And 24- Hour Emissions............................................................................. 6- 9
6.5 1- Mph/ 5- Mph Increment Comparison ........................................................................................ 6- 10
CHAPTER SEVEN
7.1 Percentage Of Carpool- Eligible Vehicles And Persons Using State Route 99
During The Peak Morning And Evening Hours ........................................................................... 7- 1
7.2 Travel Time Savings— SB PM On SR 99..................................................................................... 7- 2
7.3 Carpools Over Time On HOV And Non- HOV Freeways
( Two Peak Morning Hours in District Seven) .............................................................................. 7- 3
7.4 Accident Rates On San Bernardino County Freeways With HOV Lanes .................................. 7- 4
7.5 Average HOV Lane Flow By District ( Vehicles Per Peak Hour) ............................................... 7- 5
7.6 Percent Persons in HOV and Average Adjacent Mixed- Flow Lanes.......................................... 7- 6
7.7 HOV Lane Time Savings ( Peak Hour, Peak Direction)............................................................... 7- 7
7.8 Violation Rates Per District ........................................................................................................... 7- 8
7.9 Comparison Of Congestion Patterns In Northern And Southern California .............................. 7- 9
7.10 Chronological List Of HOV Lane Surveys In California .......................................................... 7- 10
7.11 Growth In Carpool Lane Support ................................................................................................ 7- 11
7.12 Estimated And Actual HOV Lane Time Savings ....................................................................... 7- 12
7.13 Self- Reported Impact Of HOV Lanes On Driving Patterns ( Orange County, 2003)............... 7- 13
7.14 Sample Freq Emission Rate Factors Table For Total Hydrocarbons, Carbon Monoxide,
And Oxides Of Nitrogen .............................................................................................................. 7- 15
7.15 Overview of Computation Process .............................................................................................. 7- 16
7.16 Peak- Period Emissions On Westbound I- 210 ( April 10, 2006)................................................. 7- 17
APPENDIX A
A. 1 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1990 and 55 Degrees Fahrenheit .................................................................................................. A- 2
A. 2 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1990 and 65 Degrees Fahrenheit .................................................................................................. A- 3
A. 3 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1990 and 85 Degrees Fahrenheit .................................................................................................. A- 4
A. 4 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1990 and 95 Degrees Fahrenheit .................................................................................................. A- 5
A. 5 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1995 and 55 Degrees Fahrenheit .................................................................................................. A- 6
A. 6 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1995 and 65 Degrees Fahrenheit .................................................................................................. A- 7
A. 7 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1995 and 85 Degrees Fahrenheit .................................................................................................. A- 8
A. 8 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
1995 and 95 Degrees Fahrenheit .................................................................................................. A- 9
A. 9 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
2010 and 55 Degrees Fahrenheit ................................................................................................ A- 10
A. 10 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
2010 and 65 Degrees Fahrenheit ................................................................................................ A- 11
xv
A. 11 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
2010 and 85 Degrees Fahrenheit ................................................................................................ A- 12
A. 12 Comparison of EMFAC7E and EMFAC2002 FREQ Emission Factors for
2010 and 95 Degrees Fahrenheit ................................................................................................ A- 13
APPENDIX B
B. 1 Comparison of CMEM and EMFAC2002 FREQ Emission Factors for
1990 and 75 Degrees Fahrenheit ................................................................................................... B- 2
B. 2 Comparison of CMEM and EMFAC2002 FREQ Emission Factors for
1995 and 75 Degrees Fahrenheit ................................................................................................... B- 3
B. 3 Comparison of CMEM and EMFAC2002 FREQ Emission Factors for
2010 and 75 Degrees Fahrenheit ................................................................................................... B- 4
APPENDIX C TABLES
C. 1 FREQ 1990 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 2
C. 2 FREQ 1990 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 2
C. 3 FREQ 1990 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) ...................................................... C- 3
C. 4 FREQ 1990 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 3
C. 5 FREQ 1990 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 4
C. 6 FREQ 1990 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) ..................................................... C- 4
C. 7 FREQ 1995 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 5
C. 8 FREQ 1995 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 5
C. 9 FREQ 1995 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 6
C. 10 FREQ 1995 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 6
C. 11 FREQ 1995 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 7
C. 12 FREQ 1995 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) ..................................................... C- 7
C. 13 FREQ 2000 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 8
C. 14 FREQ 2000 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 8
C. 15 FREQ 2000 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) ....................................................... C- 9
C. 16 FREQ 2000 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) ...................................................... C- 9
C. 17 FREQ 2000 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) .................................................... C- 10
C. 18 FREQ 2000 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) .................................................. C- 10
C. 19 FREQ 2005 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) .................................................... C- 11
C. 20 FREQ 2005 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) .................................................... C- 11
C. 21 FREQ 2005 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) .................................................... C- 12
C. 22 FREQ 2005 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) .................................................... C- 12
C. 23 FREQ 2005 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) ................................................... C- 13
C. 24 FREQ 2005 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) ................................................. C- 13
C. 25 FREQ 2010 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) ................................................... C- 14
C. 26 FREQ 2010 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ................................................... C- 14
C. 27 FREQ 2010 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) ................................................... C- 15
C. 28 FREQ 2010 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) ................................................... C- 15
C. 29 FREQ 2010 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) ................................................... C- 16
C. 30 FREQ 2010 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) ................................................. C- 16
C. 31 FREQ 2015 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) ................................................... C- 17
C. 32 FREQ 2015 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ................................................... C- 17
C. 33 FREQ 2015 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) ................................................... C- 18
C. 34 FREQ 2015 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) ................................................... C- 18
C. 35 FREQ 2015 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) ................................................... C- 19
xvi
C. 36 FREQ 2015 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) .................................................. C- 19
C. 37 FREQ 2020 Emission Rates at 55 ◦ Fahrenheit ( grams/ mile) .................................................... C- 20
C. 38 FREQ 2020 Emission Rates at 65 ◦ Fahrenheit ( grams/ mile) ................................................... C- 20
C. 39 FREQ 2020 Emission Rates at 75 ◦ Fahrenheit ( grams/ mile) .................................................... C- 21
C. 40 FREQ 2020 Emission Rates at 85 ◦ Fahrenheit ( grams/ mile) .................................................... C- 21
C. 41 FREQ 2020 Emission Rates at 95 ◦ Fahrenheit ( grams/ mile) .................................................... C- 22
C. 42 FREQ 2020 Emission Rates at 105 ◦ Fahrenheit ( grams/ mile) .................................................. C- 22
APPENDIX D
D. 1 District Three HOV Inventory ........................................................................................................ D- 2
D. 2 District Four HOV Inventory .............................................................................................. D- 3 to D- 9
D. 3 District Seven HOV Inventory........................................................................................ D- 10 to D- 13
D. 4 District Eight HOV Inventory....................................................................................................... D- 14
D. 5 District Eleven HOV Inventory .................................................................................................... D- 15
D. 6 District Twelve HOV Inventory ..................................................................................... D- 16 to D- 17
1- 1
CHAPTER ONE
INTRODUCTION
1.1 OVERVIEW
The implementation of freeway HOV lanes has been a controversial issue since the 1970’ s with the
Santa Monica freeway experience and continues today. While the implementation of freeway HOV
lane mileage has grown, the controversy continues, particularly from the public and
environmentalists, partly due to incomplete assessments, and, perhaps in some situations, to
questionably implemented sites. This applied research project provides factual evidence of the
effectiveness of existing HOV freeway facilities based on field data and delivers methodologies for
predicting the effectiveness of existing and proposed HOV freeway facilities from the perspectives of
both freeway performance and air quality.
1.2 RESEARCH PLAN
Six tasks were defined to accomplish the goals of this project.
.
Task 1: Comprehensive Literature Review and Synthesis of Current Knowledge
An extensive literature search was undertaken using the University of California, CALTRANS,
Transportation Research Board, and other information retrieval systems. Key project investigators
have been involved in the study of California’s HOV lanes since their inception and already had
extensive libraries of relevant reports and data. In addition, state and national experts having HOV
experience were contacted for additional input. Particular attention was given to seeking input from
CALTRANS headquarters and district staff members and the Transportation Research Board’s
Standing Committee on HOV Systems. The objective of this task was to synthesize current
knowledge of the effectiveness of HOV lanes in terms of vehicular flow, person flow, vehicle
occupancy distributions, freeway congestion, and air quality considering the HOV lane( s) and
adjacent mixed- flow lanes. The end product is a document synthesizing current knowledge and
experience of the effectiveness of HOV lanes and methods for predicting air quality.
Task 2: Assemble and Analyze Historical and Current Field Data of HOV Facilities
A major task of this study was to assemble and analyze historical and current field data of selected
HOV facilities with particular focus on existing California HOV facilities. Available historical field
data was assembled for those mainline HOV lanes currently operating in California, as well as those,
such as the Santa Monica Freeway Diamond Lanes and Alameda 580, which were once operational
but are now defunct. Wherever possible, year- by- year data was assembled, with special attention
paid to data points before and after HOV lane installation and before and after the introduction of
significant system improvements such as freeway- to- freeway connectors or adjoining HOV lanes.
In addition to historical information, available data on current performance was obtained for each
mainline HOV lane currently operating in the state. Data included vehicle volumes and occupancy
counts in the HOV lanes and adjacent mixed- flow lanes ( from CALTRANS reports); and speed and
delay data comparing HOV lanes with mainline performance ( from PeMS data).
The data analyzed included year- to- year vehicular throughput and occupancy in the HOV lanes,
mixed- flow lanes, and for the total freeway. Project team members worked with the various
1- 2
CALTRANS district offices and headquarters to identify, select, assemble, and collect selected field
data for representative locations.
Task 3: Assessment and Development of Methodologies for Estimating Air Quality
Two methodologies were developed for estimating air quality consequences of HOV lanes on
freeways. One methodology was based on the use of the FREQ simulation model that currently
includes the estimation of air quality. The other methodology was based on the use of the PeMS
database that provides on- line traffic performance information at many locations in California but
does not currently include the estimation of air quality.
The current version of the FREQ model includes the prediction of air quality as well as traffic
performance. The air quality predictions include HC, CO, and NOx as a function of predicted traffic
intensity and performance, vehicle fleet year, and vehicle classification. The air quality predictions
are made for each section of the freeway and for each time interval based on traffic performance
predictions and aggregated for the entire freeway study section over the study duration. The
previously incorporated air quality prediction subroutines were based on earlier California Air
Resources models. This methodology was assessed in light of knowledge gained from the literature
review, interviews, and synthesis of current knowledge ( Task 1). The previous methodology within
the FREQ model was modified and tested to represent the most up- to- date and comprehensive
methodology for predicting air quality.
The current PeMS database provides on- line traffic performance information such as flows, percent
occupancies, densities, and speeds for many freeway stations in California. However it does not
include air quality predictions. Based on the literature review and synthesis of current knowledge
( Task 1) and the modified air quality predictions in the FREQ model discussed in the previous
paragraph, an off- line methodology was developed and tested to estimate air quality as part of the
PeMS database. During future research, this off- line methodology could be implementation on- line
as part of the PeMS database.
Task 4: Application of Modified FREQ Model to Evaluate HOV Lanes
The modified FREQ model was applied to two freeway study sections for the purposes of
demonstrating and providing an assessment of the effectiveness of HOV lanes and their impact on air
quality. One site represents typical northern California practice ( peak- period only, unlimited access
operations, and associated cut- off levels) while the other site represents typical southern California
practice ( 24/ 7, limited access operating policies, and associated cut- off levels). The assessment
includes vehicular and person travel in the HOV lane and adjacent mixed- flow lanes as well as air
quality and fuel consumption consequences.
Sensitivity analysis were undertaken to assess the consequences on vehicular/ person travel and air
quality. The HOV lane sensitivity parameters included such elements as HOV lane location, vehicle
occupancy distribution, priority cut- off level or occupancy requirement, design, access/ egress
limitations, growth consequences, and traffic intensity level.
Task 5: Application of Off- Line Modified PeMS Database to Evaluate HOV Lanes
The modified off- line methodology for estimating air quality based on the PeMS database was
applied to one of the demonstration sites used in Task 4. One issue addressed in developing a
methodology for using PeMS data to estimate air quality was an appropriate sampling rate. Some
applications of the PeMS data base ( notably the RTMIS data base developed by SCAG) aggregate
1- 3
data on a one- hour basis. Obviously, an average speed of 40 mph over one hour will have different
air quality consequences depending on whether it was a consistent 40 mph or 30 minutes at 60 mph
and 30 minutes at 20 mph. The research team explored this issue empirically by taking speed data at
different intervals and monitoring the impact on air quality computations.
Task 6: Documentation and Presentation of the Effectiveness of HOV Lanes
The final task of the research was to develop a document that summarizes the effectiveness of HOV
lanes in terms of vehicular and person travel in the HOV lane( s) and adjacent lanes, and the
consequences to air quality. The methodologies developed are applicable to most existing HOV lane
implementations as well as to many other HOV lane implementations expected to be considered in
the near future. This document is based on the literature search and synthesis, the analysis of field
data, developed air quality modeling, the modified FREQ model demonstration applications, and the
off- line modified PeMS demonstration applications. The results of this research will be presented in
a workshop forum.
1.3 ORGANIZATION OF REPORT
This document represents the Final Report on this project. It is divided into Seven Chapters plus a
list of references and four appendices.
Chapter One is this introduction. Chapter Two describes the literature review and syntheses of
current knowledge ( Task 1). Chapter Three presents the work undertaken to assemble and analyze
historical and current field data of HOV facilities ( Task 2).
Chapter Four documents the procedures for developing methodologies for estimation air quality,
both for the freeway simulation model FREQ, and for the PeMS off- line module ( Task 3). Chapter
Five contains a detailed description and results obtained in the application of the modified FREQ
model to evaluate HOV lanes for two demonstration sites ( Task 4). Chapter Six describes the
application of the off- line methodology for estimating air quality based on the PeMS data base ( Task
5). Chapter Seven contains a summary of the project. The report also contains a list of references and
four appendices.
2- 1
CHAPTER TWO
COMPREHENSIVE LITERATURE REVIEW AND
SYNTHESIS OF CURRENT KNOWLEDGE
2.1 BACKGROUND
The HOV project’s proposal describes this task and concludes with the following paragraph:
“ Four months after the start of the research, the study team will produce an extensive
reference list, along with summaries synthesizing the state of knowledge regarding the
effectiveness of HOV lanes and their impact on air quality. This list will be a ‘ living
document’, updated throughtout the life of the project.”
In early January 2005 a progress report was distributed to Caltrans providing highlights of the
initial HOV- related literature search ( January 8, 2005, file “ hovx20). The umbrella term for this
initial search was ‘ HOV’ and a total of 922 citations were identified. This set of 922 citations
was broken down into sub- groups using additional key words. Key references for each sub- group
were briefly described and the sub- groups included the following:
• California ( 128 citations)
• Inventories ( 7 citations)
• Manuals ( 35 citations)
• Bibliographies ( 36 citations)
• Caltrans ( 50 citations)
• Guidelines ( 54 citations)
• Air Quality ( 112 citations)
• Safety ( 168 citations)
• Effectiveness/ Evaluation ( 337 citations)
• 2004 ( 21 citations)
2.2 OVERVIEW OF ACTIVITIES
The efforts on this task have gone in several directions in order to make the initial search more
comprehensive and useful for Caltrans while at the same time to identify and prepare a synthesis
of the most significant documents. These efforts have included further literature searches,
obtaining guidance from a number of individuals including representatives of the project team,
Caltrans, TRB’s HOV Systems Committee, and other selected individuals. The team has also
been participating in two current nationally pooled- funded HOV projects in which Caltrans is one
of the sponsors. Finally, attention has been given to HOV- related web sites.
The products of these effort includes: 1) separate delivery of five copies of a CD containing
abstracts of the citations for each of the previous mentioned sub- groups and ( 2) this synthesis of
the most significant documents and other sources.
The following synthesis is divided into two major sections. In the first section, a one- page
description of the eleven references that appear to be most significant are provided with title,
source, date, authors, availability, abstract, and content. The second section provides reference
citations of other selected recent documents divided into three groups: California, Other States,
and Other.
2- 2
2.3 SIGNIFICANT REFERENCES
The one- page description of the eleven references that appear to be the most significant are listed
in this section.
HOV SYSTEMS MANUAL
Source: Transportation Research Board ( NCHRP Report 414)
Date: 1998
Authors Texas Transportation Institute, Parsons- Brinckerhoff, and Pacific Rim Resources
Availability: ITS Library (. TA, 1001.5, . N3, no. 315)
Abstract: This report is a comprehensive and detailed HOV systems Manual that
incorporates current guidelines and practices. The contents of this Manual are,
therefore, of immediate interest to both highway and transit professionals in
planning, designing, implementing, operating, marketing, and enforcing HOV
systems. The Manual is also useful to those charged with achieving air- quality
and congestion- management goals as well as policy makers.
Contents Chapter 1 Guide to the HOV Systems Manual
Chapter 2 Introduction to HOV Facilities
Chapter 3 Policy Considerations with HOV Facilities
Chapter 4 Planning HOV Facilities
Chapter 5 Operation and Enforcement of HOV Facilities on Freeways and
in Separate Rights- of- Way
Chapter 6 Design of HOV Facilities on Freeways and in Separate Rights-of-
Way
Chapter 7 Operation and Enforcement of Arterial Street HOV Facilities
Chapter 8 Design of Arterial Street HOV Facilities
Chapter 9 Transit and Support Services and Facilities
Chapter 10 Supporting Programs and Policies
Chapter 11 Implementing HOV Facilities
Chapter 12 Public Involvement and Marketing Programs
Chapter 13 Monitoring and Evaluating HOV Facilities
2- 3
GUIDE FOR HIGH- OCCUPANCY VEHICLE FACITIES
Source: American Association of State Highway and Transportation Officials ( GHOV- 3)
Date: November 2004
Authors AASHTO Subcommittee on Design
Availability: ITS Library ( HE336, . B8G84, 2004a)
Abstract: This guide is intended as just that – a guide. Where this guide does not provide
specific geometric information, please refer to “ A Policy on Geometric Design of
Highways and Streets” for guidance. In some chapters, this guide provides
desirable and minimum cross- sections and design criteria. Prior to implementing
designs that are less than the minimums, an engineering review should be
completed with respect to the safety and operational impacts of these geometric
elements and their justification. For minimum designs, the designer should
review Section 2.1, which describes the link between design, operations, and
enforcement of HOV facilities to better understand the conditions under which
the minimum designs might be appropriate and what operational treatments
might be necessary. The Federal Highway Administration ( FHWA), Federal
Transit Administration ( FTA), state Department of Transportation ( DOT), transit
agency, city, and others should agree on the most appropriate cross- section and
other geometric design elements. A formal design exception request may need to
be processed to document the decisions and their approvals.
Contents Chapter 1 Planning for Freeway and Arterial HOV Facilities
Chapter 2 Operating and Enforcing HOV Facilities on Freeways
Chapter 3 Design of HOV Facilities on Freeways
Chapter 4 Operating and Enforcing HOV Facilities on Arterial Streets
Chapter 5 Design of HOV Facilities on Arterial Streets
2- 4
HOV LANE ELIGIBILITY REQUIREMENTS AND OPERATING HOURS HANDBOOK
Source: HOV Pooled Fund Study and Federal Highway Administration
Date: Draft Final Report ( May 2006)
Authors Battelle Memorial Institute and Texas Transportation Institute
Availability: Battelle Memorial Institute and Texas Transportation Institute
Federal Highway Administration
Abstract: Welcome to the HOV Lane Eligibility Requirements and Operating Hours
Handbook. This handbook provides a comprehensive guide to assessing the
potential impacts of changes in eligibility requirements and operating hours on
high- occupancy vehicle facilities. While the handbook focuses on assessing
potential changes in the operation of existing HOV lanes, if may also be used in
planning new HOV facilities. The handbook is intended to meet the needs of
various audiences. The primary audience of the handbook is transportation
professionals responsible for planning, designing, funding, operating, enforcing,
and managing HOV facilities. The secondary audience includes agency
management personnel, policy makers, and other individuals interested in the
effective and efficient operation of HOV lanes.
Contents Chapter 1 Introduction
Chapter 2 Executive Summary
Chapter 3 Managing HOV Lanes
Chapter 4 Assessing Vehicle Eligibility Requirements
Chapter 5 Assessing Vehicle- Occupancy Requirements
Chapter 6 Assessing HOV Operating Hours
Chapter 7 Case Studies
2- 5
HOV LANE ENFORCEMENT HANDBOOK
Source: HOV Pooled Fund Study and Federal Highway Administration
Date: Final Draft March 2006
Authors Texas Transportation Institute and Battelle Memorial Institute
Availability: Texas Transportation Institute, Battelle Memorial Institute, and
Federal Highway Administration
Abstract: The Handbook will be of use to agencies involved in the planning, development,
and implementation of 1) HOV enforcement policies and programs, and 2) the
planning, design, and operation of HOV facilities. The audience for the
Handbook and the supporting products includes representatives from state
departments of transportation ( DOT), Metropolitan Planning Organizations
( MPOs), transit agencies, enforcement agencies, and other agencies responsible
for planning, designing, developing, operating, and enforcing HOV facilities.
The targeted end users of the Handbook includes planners, engineers, managers,
and other staff at these agencies. The supporting materials are targeted toward
top- level agency staff and policy makers.
Contents Chapter 1 Introduction
Chapter 2 Overview of HOV Lane Enforcement
Chapter 3 Enforcement Considerations in HOV Planning
Chapter 4 Enforcement Considerations in HOV Facility Design
Chapter 5 Enforcement Considerations in HOV Facility Operations
Chapter 6 Enforcement Considerations for HOT Facilities
Chapter 7 Enforcement Considerations for Exempt Vehicles on HOV
Facilities
Chapter 8 Legislative and Judicial Issues in HOV and HOT Enforcement
Chapter 9 Enforcement Technologies
2- 6
A REGIONAL HIGH OCCUPANCY VEHICLE SYSTEM PERFORMANCE STUDY
FOR ORANGE, SAN BERNARDINO, AND RIVERSIDE COUNTIES
Source: Southern California Association of Governments ( SCAG).
Date: September 2004
Authors Systan Inc.
Availability: Systan
Abstract: The High Occupancy Vehicle system in California has recently been the subject
of media attention and legislature scrutiny, most notably in a January 2000 report
from the legislation analysts office, which posed the question “ HOV Lanes in
Calfornia Are They Achieving Their Goal?” To answer this question and to
respond to the media and legislature attention and concerns expressed by policy
makers, the Southern California Association of Governments ( SCAG) has
engaged Systan et al to undertake a regional high- occupancy vehicle system
performance study designed to ensure that the HOV facilities of Orange, San
Bernardino, and Riverside Counties obtain the best possible performance from
existing and planned investments.
Contents Chapter 1 Introduction
Chapter 2 System Performance
Chapter 3 Market Research
Chapter 4 Traffic Forecasts
Chapter 5 Design/ Operation Issues
Chapter 6 Recommendations
2- 7
2002 HIGH OCCUPANCY VEHICLE LANE MASTER PLAN UPDATE
Source: Metropolitan Transportation Commission, Caltrans District 4 and the California
Highway Patrol Golden Gate Division
Date: January 2003
Authors DKS and Parsons Brinckerhoff
Availability: DKS
Abstract: The 2002 HOV Lane Master Plan includes a thorough review of current HOV
lane performance. An assessment of HOV lane forecasts ( 2025) from the latest
modeling conducted for the 2001 Regional Transportation Plan ( RTP), and more
current forecasts ( 2010) developed specifically for this plan also were completed.
This assessment has led to the development of recommendations for how the
HOV lane system could be expanded beyond what is already included in the
2001 RTP. HOV lane improvements that support further development of MTC’s
Regional Express Bus Program also have been of particular interest as part of the
plan update, and the study includes recommendations for expansion of the
express bus operations in the region.
Contents Chapter 1 Project Purpose and Background
Chapter 2 Key Findings and Recommendations
Chapter 3 What Does the Public Think of HOV Lanes?
Chapter 4 Evaluation of the System’s Performance
Chapter 5 Recommendations for HOV Lane System Improvements and
Operational Changes
Chapter 6 HOV Lane Enforcement
Chapter 7 Consideration of High- Occupancy- Toll ( HOT) Lanes
Chapter 8 Express Bus Recommendations
Chapter 9 Recommended HOV Lane System Infrastructure Costs
Chapter 10 Recommendations by County and Corridor
Chapter 11 Air Quality Analysis
2- 8
FHWA/ TRB MANAGED AND PRICED LANES WORKSHOP
Source: Federal Highway Administration and Transportation Research Board
Date: November 18- 19, 2003
Authors Federal Highway Administration and Transportation Research Board
Availability: Federal Highway Administration and Transportation Research Board
Abstract: Potential policy, program and research initiatives to advance the planning,
implementation and operation of managed lanes were the focus of the
Transportation Research Board ( TRB) and Federal Highway Administration
( FHWA) two- day workshop in Key Biscayne, Florida on November 18 and 19,
2003. The objectives of the workshop were ( 1) to identify and prioritize potential
research and technology transfer activities to advance the implementation of
managed and priced lanes; and ( 2) to identify opportunities to champion and
advance managed and price lane research- related initiatives, particularly within
TRB. The structure of the workshop allowed participants to spend the first day
focused on the broader concept of managed lanes, while the focus of the second
day was narrowed to address priced lanes. This workshop serves as a first step
by FHWA and TRB to receive focused feedback on managed lane issues.
Further efforts to obtain feedback in the future can be expected as additional
planning and coordination takes place.
Contents Chapter 1 Summary of Workshop Results
Chapter 2 Workshop Day 1 – Managed Lanes
Chapter 3 Workshop Day 2 – Priced Lanes
Chapter 4 Day 1/ Topic Areas
Chapter 5 Day 2/ Topic Areas
2- 9
A GUIDE FOR HOT LANE DEVELOPMENT
Source: Federal Highway Administration
Date: 2003
Authors Parsons Brinckerhoff and Texas Transportation Institute
Availability: Federal Highway Administration
Abstract: This guide is intended to be a comprehensive source of collective experience
gained from the nation’s current and implemented high occupancy toll ( HOT)
lane projects. The guide presents a wide range of information on HOT lanes and
is intended to assist transportation professionals contemplating specific projects,
as well as others who wish to become more informed on the topic. While most
transportation officials are familiar with the HOT lane concept, relatively few
have had first hand experience with actual HOT facilities. Therefore, the need to
learn from current experience is particularly important.
Contents Chapter 1 HOT Lane Concept and Rationale
Chapter 2 HOT Lane Planning and Implementation Process
Chapter 3 Organizational Frameworks for HOT Lane Projects
Chapter 4 Achieving Public Acceptance
Chapter 5 Technical Issues
Chapter 6 Operational Issues
Chapter 7 Current HOT Lane Experience
Chapter 8 Benefits and Lessons Learned
Chapter 9 Glossary
2- 10
FREEWAYS, HIGH- OCCUPANCY VEHICLE SYSTEMS, AND TRAFFIC SIGNAL
SYSTEMS
Source: Transportation Research Board, Record 1856
Date: 2003
Authors As indicated below
Availability: Transportation Research Board
Abstract: The 2003 series of the Transportation Research Record: Journal of the
Transportation Research Board consists of approximating 650 papers selected
from 2100 submissions after rigorous peer review. The peer review for each
paper published in this volume was coordinated by the sponsoring committee
acknowledged at the end of the text; members of the sponsoring committees for
the papers in this volume are listed in page ii. Many of these papers were
presented a the TRB 82nd Annual Meeting in January 2003, and draft versions
were included in the Annual Meeting Compendium of Papers CD- ROM. This
particular record, Record 1856, contains papers sponsored by the Freeway
Operations, HOV Systems, and Traffic Signal Systems Committees. There were
four papers listed below that dealt with HOV Systems.
Contents Katherine F. Turnbull et al, “ Effects of Changing Occupancy Requirements for
High- Occupancy Vehicle Lane: El Monte Busway Case Study”.
Darren Henderson, “ State of the Practice in High- Occupancy Vehicle System
Performance Monitoring”.
Myron Swisher et al, “ Life- Cycle Graphical Representation of Managed High-
Occupancy Vehicle Lane Evolution”.
Beverly Kuhn et al, “ State Legislative Issues for Managed Lanes in Texas”.
2- 11
HOV LANES IN CALIFORNIA:
ARE THEY ACHIEVING THEIR GOALS
Source: Legislative Analyst’s Office
Date: January 7, 2000
Authors Rebecca Long ( under supervisor of Dana Curry)
Availability: Legislative Analyst’s Office
Abstract: High occupancy vehicle ( HOV) lanes have been a central part of California’s
strategy for alleviating congestion. Today, HOV lanes cover 925 lane miles of
the state highway system and plans are underway to double this system over the
next 20 years. Given population projections for the state ( expected to grow by
over 30 percent by 2020) and the limited amount of capacity on the state highway
system, the Legislature, the Department of Transportation ( Caltrans), and
regional transportation planning agencies ( RTPAs) ought to take a closer look at
the degree to which HOV lanes are achieving the goals of congestion relief and
improved air quality. This report examines the performance of the state’s HOV
lanes. It provides options to modify their use in order to ensure that the existing
HOV lane infrastructure is used most efficiently and any future investments in
HOV lanes will further the goal of congestion relief and improved air quality.
Contents Chapter 1 Introduction
Chapter 2 Congestion in California
Chapter 3 Congestion Relief Efforts
Chapter 4 Overview of California’s HOV Lanes
Chapter 5 Criticism of HOV Lanes
Chapter 6 Recent Legislation in California
Chapter 7 Measuring Performance of HOV Lanes
Chapter 8 Incentives to Carpool
Chapter 9 Impact on Air Quality Unclear
Chapter 10 Summary of Findings
Chapter 11 Options for California’s HOV Lanes
Chapter 12 HOT Lane Case Study: Interstate 15 in San Diego
Chapter 13 Conclusion
2- 12
MANAGED LANES WEB SITE
TEXAS TRANSPORTATION INSTITUTE
Source: Texas A& M University and Texas Department of Transportation
Date: Continuously being updated
Authors Texas Transportation Institute
Availability: Web Site “ http:// managed- lanes. tamu. edu”
Abstract: Working in support of the research sponsors, TxDOT and the Federal Highway
Administration, the Texas Transportation Institute ( TTI), assisted by Texas
Southern University, is investigating the complex and interrelated issues
surrounding the safe and efficient operation of managed lanes and is developing a
managed lanes manual to help TxDOT make informed planning, design, and
operational decisions when considering these facilities for their jurisdiction. This
multi- year project has a considerable number of tasks that focus on topics within
the key thrust areas of planning, design, and operations of managed lanes
facilities. One activity of this program was the development and now the
continuous updating of the ‘ managed lane’ web site. The web site is divided into
six major parts.
Contents Section 1 About this project
Section 2 News
Section 3 Our Products
Section 4 Meetings and Events
Section 5 E- mail List Information
Section 6 Related Work
2- 13
2.4 OTHER SELECTED RECENT REFERENCES
2.4.1 California
1. Caltrans, Ramp Meter Design Manual, California Department of Transportation, Sacramento,
California, January 2000.
2. Caltrans Division of Traffic Operations, High- Occupancy Vehicle ( HOV) Guidelines for
Planning, Design, and Operations, California Department of Transportation, Sacramento,
California, August 2003.
3. Los Angeles County Metropolitan Transportation Authority, HOV Performance Program
Evaluation Report, prepared by Parsons Brinckerhoff, November 2002.
4. J. Rodier- Caroline et al, A Comparison of High Occupancy Vehicle, High Occupancy Toll,
and Truck Only Lanes in the Sacramento Area, University of California at Davis, 1999.
5. Yonnel Gardes et al, Bay Area Simulation and Ramp Metering Study, University of
California PATH Program, 2003
6. J. Supernak et al, San Diego’s Interstate 15 Congestion Pricing Project: Traffic- Related
Issues, Transportation Research Board, Record 1812, 2002.
7. Parson Brinckerhoff, Orange County High- Occupancy Vehicle ( HOV) Operations Policy
Study, Parsons Brinckerhoff, August 2002.
8. K. F. Turnbull et al, Effects of Changing Occupancy Requirements for High- Occupancy
Vehicle Lane – El Monte Busway Case Study, Transportation Research Board, Record 1856,
2003.
9. Edward Sullivan, Continuation Study to Evaluate the Impacts of the SR 91 Value- Priced
Express Lanes, Cal Poly State University, December 2000.
10. T. Gaul et al, The Los Angeles County HOV Performance Program Study, Institute of
Transportation Engineers Annual Meeting, 2003.
11. W. R. Loudon et al, San Francisco Bay Area High- Occupancy Vehicle ( HOV) Lane Master
Plan, Institute of Transportation Engineers Annual Meeting, 2003.
12. Joy Dahlgren, High- Occupancy/ Toll Lanes: Where should they be implemented?,
Transportation Research, Part A, Vol. 36A, No. 3, pages 239- 255, 2002.
13. George Gray et al, Non- Pricing Methods to Optimize High Occupancy Vehicle Lane Usage,
Mineta Transportation Institute, San Jose State University, September 2001.
14. W. Dietrich et al, Reversible HOV Lane US 101 Marin County Gap Closure Project, Institute
of Transportation Engineers, Annual District Meeting, San Diego, California, 2000.
15. Urban Transportation Monitor, Caltrans Right, California Legislature Wrong, Vol. 14, No,
13, July 7, 2000.
2- 14
16. Mineta Transportation Institute, Regional Transportation Hot Spot Forum: Marin/ Sonoma
101 Corridor, San Jose State University, April 2002.
17. California Department of Transportation, Governor’s Traffic Congestion Relief Program,
Caltrans Journal, 2( 5), 2002/ 2003.
18. Carlos Daganzo et al, Ten Strategies for Freeway Congestion Mitigation with Advanced
Technologies, University of California PATH program, 2002.
19. Eugene Kim, HOT Lanes: A Comparative Evaluation of Costs, Benefits, and Performance,
Dissertation, University of California at Los Angeles, 2000.
20. J. H. Green, HOT Lane Study for State Route 57 in Orange County, Institute of Transportation
Engineers, Annual Meeting, Nashville, Tennessee, 2000.
21. R. Poole, Are Hybrids Right for HOV Lanes?, IRRD- OECD, World Highways, 13( 5), 2004.
2.4.2 Other States
22. Washington Department of Transportation, Washington State Freeway HOV System Policy:
Executive Summary, Washington Department of Transportation, Olympia, Washington, 1992.
23. University Transportation Centers Program, Evaluation of the Effectiveness of High
Occupancy Vehicle Lanes, prepared by the University of Utah, 2004.
24. D. A. Skowronek et al, Dallas Area Guidance for HOV Lane Implementation, Texas A& M
University, 2003.
25. K. F. Turnbull, Houston Managed Lanes Case Study: The Evolution of the Houston HOV
System, Texas A& M University, 2003.
26. Minnesota Department of Transportation, Freeway Corridor Management and Preferential
Treatment for HOVs, Traffic Engineering Manual, July 2000.
27. Minnesota Department of Transportation, High Occupancy Vehicle ( HOV) Ramp Bypass
Lanes, Road Design Manual, March 2001.
28. M. Swisher et al, Colorado Value Express Lanes Feasibility Study, Colorado Department of
Transportation and UrbanTrans Consultants, Denver, Colorado, March 2001.
29. F. L. Spielberg, Dynamic Carpool Formation on the I- 95/ I- 395 Corridor in Northern
Virginia, Transportation Research Board, Record 1711, 2000.
30. New Jersey Department of Transportation, New Jersey I- 80 and I- 287 HOV Lane Case Study,
2002.
31. M. D. Hoffman et al, Maryland’s High Occupancy Vehicle ( HOV) Lanes: Who is Using Them
and Why?, Texas Transportation Institute, 2001.
2- 15
32. N. L. O’Connell et al, HOV Lanes on the Long Island Expressway: How are they doing?,
Texas Transportation Institute, 2001.
33. P. Murray et al, Defining Special- Use Lanes: Case Studies and Guidelines, Center for
Transportation Research, University of Texas, 2000.
34. S. Ishak et al, Statistical Evaluation of I- 4 Florida Traffic Prediction System, Transportation
Research Board, Record 1856, 2003.
35. A. S. Cothron et al, Crash Analysis of Selected High- Occupancy Vehicle Facilities in Texas,
Texas Transportation Institute, 2004.
2.4.3 Other
36. AASHTO, A Policy on Geometric Design of Highways and Streets, American Association of
State Highway Officials. Washington D. C., 2001.
37. TRB, Highway Capacity Manual, Transportation Research Board, 2000.
38. C. Fuhs and J. Obenberger, Development of High- Occupancy Vehicle Facilities: Review of
National Trends, Transportation Research Board, Record 1781, pp 1- 9, 2002.
39. Federal Highway Administration, 10th International Conference on High- Occupancy Vehicle
Systems, Compendium of Papers, Held in Dallas, Texas, 2001.
40. L. G. Neudorff et al, Freeway Management and Operations Handbook, Federal Highway
Administration, 2003.
41. J. E. Evans et al, Traveler Response to Transportation System Changes Manual,
Transportation Research Board, 2003.
42. Transport Research Laboratory, High- Occupancy Vehicle Lanes Update, TRL, United
Kingdom, 2002.
43. Billheimer, John, J. B. Moore, and Heidi Stamm, High Occupancy Vehicle ( HOV) Lane
Marketing Manual, prepared for the Federal Highway Administration ( DOT- T- 95- 04) by
SYSTAN, Inc. Los Altos, CA, September 1994. ( to be updated in FY 2007/ 08).
2.5 UPDATE OF LITERATURE REVIEW
The project team has reviewed contributions appearing in the literature since the initial literature
search was conducted and has added the following references to the list of key contributions.
44. Cassidy, Michael J., Carlos F. Daganzo, Kitae Jang, and Koohong Chung, Empirical
Reassessment of Traffic Operations: Freeway Bottlenecks and the Case for HOV Lanes,
Institute of Transportation Studies, University of California, Berkeley, CA, Research Report
No. UCB- ITS- RR- 2006- 6, December 2006.
2- 16
45. Chung, Koohong, Ching- Yao Chan, Kitae jang, David R. Ragland, and Yong- Hee Kim, HOV
Lane Configurations and Collision Distribution on Freeway Lanes— An Investigation of
Historical Collision Data in California, paper presented at 86th Annual Meeting of the
Transportation Research Board, Washington, D. C., January 2007.
46. Cothron, A. Scott, Stephen E. Ranft, Carol H. Walters, David W. Fenno, and Dominique
Lord, Crash Analysis of Selected High- Occupancy Vehicle Facilities in Texas:
Methodology, Findings, and Recommendations, Report No. FHWA/ TX- 04/ 0- 4434- 1,
prepared by Texas Transportation Institute for FHWA, May 2004.
47. Ojah, Mark, and Ginger Goodin, Examination of Selected Safety Considerations in the
Development of HOV Facilities, paper presented at 85th Annual Meeting of the Transportation
Research Board, Washington, D. C., January 2006.
48. TRB, Air Quality 2006, Transportation Research Board, 2006.
49. Turnbull, Katherine, HOV Performance Monitoring, Evaluating, and Reporting Handbook,
prepared by Texas Transportation Institute for FHWA, December, 2005.
50. Turnbull, Katherine, HOV Lanes and Hybrid Vehicles, presented at the 86th Annual Meeting
of the Transportation Research Board, Washington, D. C., January 2007.
In addition, the team has identified eighty other HOV references appearing in the years between
2005 and 2007 and has added these references to the overall list of citations originally prepared in
Task 1.
3- 1
CHAPTER THREE
PERFORMANCE OF CALIFORNIA HOV LANES
3.1 OVERVIEW
Task Two of this investigation of the effectiveness of HOV lanes entailed an analysis of historical and
current field data on California’s HOV facilities. Available historical field data were assembled for
those mainline HOV lanes currently operating in the state, as well as those, such as the Santa Monica
Freeway Diamond Lanes, which were once operational but are now defunct. Wherever possible,
year- by- year data were assembled, with special attention paid to data points before and after HOV
lane installation and before and after the introduction of significant system improvements.
Figure 3.1 lists the number of directional miles of HOV lanes in each CALTRANS District as
reported in the most recent District HOV reports available in December 2005. In all, nearly 1200
miles of HOV lanes exist throughout the state. Those districts not listed in the figure currently have
no operating HOV lanes, although District Five in San Luis Obispo has plans on the drawing board
for HOV lanes on Route 101 in Santa Barbara and Route 1 in Santa Cruz.
Figure 3.1. HOV Lane Miles by District
Data availability varied widely from district to district. Districts 3, 4, and 7 had typically collected
performance data conscientiously, while records of other districts showed significant gaps. Few
districts collected the “ Before” data needed to support detailed “ Before/ After studies of the impacts of
HOV lanes. The following sections of this chapter organize findings for each District in terms of
historical trends, current performance, and public opinion.
DISTRICT NO. HOV LANE
MI L E S
DISTRICT THREE 70.8
DISTRICT FOUR 318.5
DISTRICT SEVEN 422.6
DISTRICT EIGHT 91.2
DISTRICT ELEVEN 28.3
DISTRICT TWELVE 240.9
TOTAL 1172.3
3- 2
3.2 DISTRICT THREE
3.2.1 System Map
CALTRANS District Three comprises eleven counties in the Sacramento Valley and Northern
Sierras. As of December, 2003, the area had 70.8 directional miles of HOV lanes in the Sacramento
Metropolitan Area, including
• 28.6 miles ( 14.3 in each direction) on State Route 99 running from south of Elk Grove
Boulevard to E Street on Route 51;
• 23.0 miles ( 11.5 in each direction) on US- 50 between El Dorado Hills Boulevard and Sunrise
Boulevard; and
• 19.2 miles ( 9.6 in each direction) on Interstate 80 between Riverside Boulevard and
Longview Drive.
A map of existing HOV freeway routes in District Three appears in Figure 3.2.
3.2.2 HOV Freeway Inventory
Current Information Appendix D contains an inventory of HOV freeway lanes in District Three. The
inventory, assembled from data in the most recent ( December 2004) District Three HOV Report, lists
routes and lane miles by direction, along with occupancy requirements, operating hours, opening
dates, and dates and descriptions of subsequent modifications. All HOV lanes in District Three
require two or more occupants for legal use of the lanes.
Data Availability. District Three has produced detailed annual reports on their HOV system for the
years 1991 through 2004. These reports include data on traffic volumes, people movement,
occupancy rates, violations, enforcement, accidents, and time savings. “ Before” data documenting
corridor operations prior to lane installation each of the three major area HOV lanes are also available
in these references.
3- 3
Figure 3.2 District Three High Occupancy Vehicle Lanes
3- 4
3.2.3 Historical System Performance
The following charts document various aspects of the year- by- year performance of the HOV lanes on
State Route 99 in District Three from their inception to 2003.
Growth of Volume. Figure 3.3 plots the growth of traffic volumes in the SR- 99 HOV lanes from
their introduction in November 1990 through 2003.
VEHICLES/ HOUR SB- PM: STATE ROUTE 99
0
1000
2000
3000
4000
5000
6000
7000
8000
BEFORE HOV
BEFORE HOV
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Y E A R
VEHICLES/ HOUR
HOV- TOT
MIX- TOT
TOT
MIX: TOT/ LANE
Figure 3.3 HOV Lane Traffic Over Time ( Veh/ Hr, SB PM)
State Route 99: Caltrans District Three
The figure shows a steady growth in the volume of traffic using the southbound HOV lane on SR 99
during the peak evening hour. During the first year of operation, only 550 vehicles were observed
using the lane during the peak hour. By 2003, this volume had grown to 1420 vehicles per hour, just
below the average of 1560 vehicles per hour observed in the three mixed flow lanes. While traffic in
the HOV lanes was growing over time, traffic in the mixed flow lanes was dropping slightly. By
2003, therefore, when the number of vehicles in the average mixed flow lane had fallen to within 10%
of the number in the HOV lane, the HOV lane was carrying 83% more people than the average mixed
flow lane.
3- 5
Incidence of Ridesharing. Figure 3.4 plots the growth in the incidence of ridesharing on State Route
99 from the introduction of the HOV lanes in November 1990 through 2003.
PERCENT CARPOOL- ELIGIBLE VEHICLES AND PERSONS ( PEAK HOUR, PEAK
DIRECTION) STATE ROUTE 99
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
BEFORE HOV
BEFORE HOV
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Y E A R
% CARPOOL- ELIGIBLE VEHICLES
% CP VEH: PK DIR
% CP PER: PK DIR
Figure 3.4 Percentage Of Carpool- Eligible Vehicles And Persons
Using State Route 99 During The Peak Morning And Evening Hours
As would be expected, the increase in HOV lane traffic on State Route 99 has been accompanied by
an increase in the incidence of ridesharing. When HOV lanes were introduced in November 1990,
the percentage of vehicles carrying two or more persons during the peak hour jumped from 18.3% to
22.8%, while the number of people in these vehicles jumped from 26.0% of those using the freeway
to 41.1%. The incidence of ridesharing vehicles and persons held fairly steady for seven years, and
then rose again following the lengthening of the HOV lanes in 1997. By 2003, the incidence of
vehicles carrying two or more persons had risen to 27.7%, just over one quarter of the peak- hour
traffic, while the number of persons in these vehicles had risen to 48.7% of all those using the
freeway.
3- 6
Time Savings. Figure 3.5 shows the travel times in the southbound HOV lane and adjacent mixed
flow lanes on State Route 99 from1990 through 2003. When the HOV lanes were first introduced,
the time savings available over their 3.9 mile length were relatively small— amounting to less than
one minute. As congestion increased in the mixed flow lanes, the available time savings jumped to 4
minutes in 1995, and rose again to 5.5 minutes in 1997, when the length of the HOV lanes was
extended from 3.9 miles to 9.7 miles. By 2003, the recorded savings had risen to 6.67 minutes, or
just under a half minute per mile over the 14.3 mile length of the lanes.
TRAVEL TIMES: SB PM on STATE ROUTE 99 ( 14.3 miles)
0
5
10
15
20
25
BEFORE HOV
BEFORE HOV
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Y E A R
TRAVEL TIME ( min)
HOV TIME
MIX TIME
SAVINGS
Figure 3.5 Travel Time Savings— SB PM On SR 99
Caltrans District Three
3- 7
Violation Rates. Figure 3.6 tracks the violation rates observed during the peak hour of travel in the
Northbound and Southbound HOV lanes on State Route 99.
VIOLATION RATES OVER TIME
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
BEFORE HOV
BEFORE HOV
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Y E A R
VIOLATION RATE (%)
VIOL % NB AM
VIOL % SB PM
Figure 3.6 Violation Rates Over Time
State Route 99, Caltrans District Three
Violation rates on the State Route 99 HOV lanes have grown over time in both the northbound and
southbound directions. In the southbound direction, violation rates during the peak evening hour
currently hover around 10%, the level generally identified as the limit of acceptability. In the
northbound direction, violation rates rose above this level ( to 15%) in both 1999 and 2000, but counts
during the morning peak in these years were affected by darkness. Past studies have shown that
violation rates typically increase during pre- daylight periods, when it is hard to detect the number of
occupants in a car visually and, consequently, violations are difficult to enforce.
3.2.4 Safety
Figure 3.7 tracks the accident rates recorded in the Northbound and Southbound directions over the
stretches of State Route 99 augmented by HOV lanes. The depicted rates are measured in accidents
per million vehicle miles over a 24- hour period, but the majority of recorded accidents reflect
collisions occurring during the commute hours when HOV lanes were operating.
3- 8
ACCIDENTS/ MVM OVER TIME ( SR- 99)
0
0.5
1
1.5
2
2.5
BEFORE HOV
BEFORE HOV
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
YEAR
A C C / MVM
ACC/ MVM: NB
ACC/ MVM: SB
ACC/ MVM: NB + SB
Figure 3.7 Accidents Per MVM On SR 99
The chart shows that accident rates remained relatively stable during the first three years following
the introduction of HOV lanes on SR 99, and then followed an upward trend between 1995 and 2003.
By 2003, the reported number of accidents per million vehicle miles in both directions had reached
1.6, an increase of 42% over the rate of 1.125 reported just before the HOV lanes were introduced.
Accident rates were heaviest in the northbound direction, reportedly because the congestion in that
direction is more pronounced during the morning peak.
The annual HOV reports produced by District Three note that the accident rates experienced on SR
99 are “… not unusual when compared with other freeway segments in Sacramento” ( 1999 report) and
there is “… no indication that HOV lanes have caused an increase in actual accident rates” ( 1996
report).
The question of safety is one of the most vexing associated with HOV lane operations. On some
projects, such as the Santa Monica Diamond Lanes and Route 237 in Santa Clara, California, accident
rates have increased significantly following the introduction of HOV lanes. Yet other concurrent
flow lanes have been installed with no increase in accidents. District Three’s HOV lane reports
suggest that the majority of collisions comprising the accident rate are congestion related and occur
during commute hours. Another study of HOV lane safety has noted that “… the traffic congestion
experienced on the freeway overwhelmed all other factors in determining safety. “ Yet, by
definition, the HOV lanes rely on congestion for the travel time savings needed to attract carpoolers.
To the extent that the congestion accompanying the introduction of HOV lanes causes accidents,
therefore, the lanes should be held accountable.
3- 9
3.2.5 Current System Performance
The following charts offer lane- by- lane comparisons of such key performance measures as vehicle
volumes, occupancies, travel time savings, and violation rates for the most recent year available,
2003.
Peak Hour Traffic Volumes. Recent vehicle volumes on District Three’s HOV lanes are graphed in
Figure 3.8, which shows peak- hour volumes in the peak direction of morning and evening flow.
0
200
400
600
800
1000
1200
1400
1600
1800
SR- 99 SR- 99 US- 50 US- 50 I- 80 I- 80 ALL LANES
AM PM AM PM AM PM = PK DIR
NB SB WB EB WB EB = WB& EB
FREEWAY HOV LANE
HOV LANE VEHICLES/ HR
1650 Veh per Hour
800 Veh per Hour
Average: 1055 Vehicles/ Hour
Figure 3.8 Peak Hour Vehicle Volumes, 2003/ 04
Caltrans District Three HOV Lanes
The horizontal lines of Figure 3.8 represent two generally recognized operating standards for HOV
lanes.
( 1) The lower level of 800 vehicles per hour, which is generally recognized as the
minimum operating standard for a mature HOV lane ( HOV Systems Manual,
NCHRP Report 414). Operations below this level can experience the “ empty lane
syndrome” at which lanes appear underutilized.
( 2) The upper level of 1650 vehicles per hour, at which point free- flow operations can
begin to deteriorate, causing the time advantage offered by the HOV lanes to
disappear. ( Parsons Brinckerhoff, 2002)
3- 10
As indicated in Figure 3.8, peak- hour vehicle volumes on all District Three HOV lanes either exceed
or are just slightly lower than 800 vehicles per hour. This is true even of the most recently opened
HOV lanes on I- 80. In fact, the average peak- hour volume on all operating District Three lanes is
1055 vehicles per hour, so there is little danger that these lanes will fall victim to the “ empty lane
syndrome.” In fact, the HOV lanes on SR- 99 are currently approaching the upper limits of their
capacity during the peak morning commute period.
Person Volumes. Figure 3.9 compares the percentage of freeway person trips carried by District
Three HOV lanes and adjacent mixed- flow lanes in the primary direction of flow during the peak
morning and evening commute hours.
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
40.00%
45.00%
SR- 99 SR- 99 US- 50 US- 50 I- 80 I- 80 ALL LANES
AM PM AM PM AM PM = PK DIR
NB SB WB EB WB EB = WB& EB
FREEWAY HOV LANE
% PERSONS per LANE ( ave peak hour)
% PER IN HOV LANE
% PER IN MIX FLOW
Figure 3.9 Percent Persons In HOV And Average Mixed- Flow Lanes
( 2003/ 04: Peak Hour, Peak Direction)
As would be expected, in nearly every case, the percentage of freeway travelers carried by the HOV
lanes is significantly greater than the percentage carried by the average adjacent mixed- flow lane.
The only exception is the recently formed HOV segment on eastbound US- 50 during the evening
peak. In all other cases, HOV lanes carry at least as many people as the average adjacent mixed- flow
lanes in both peak directions. During the morning peak on northbound SR- 99, moreover, the HOV
lane carries more than double the number of people in the average mixed- flow lane. On the average,
HOV lanes carry 27.3% of the people in District Three corridors, while the average adjacent mixed-flow
lane carries only 20.6%. the predominant person- carrying capacity of the HOV lanes is
achieved primarily through carpools, with relatively small contributions from buses.
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Travel Time Savings. Figure 3.10 graphs the time savings available on each leg of District Three’s
HOV freeway network. Time savings were calculated by comparing the travel times of vehicles
traveling the entire length of individual HOV lanes with the corresponding times recorded by vehicles
in adjacent mixed- flow lanes.
0
2
4
6
8
10
12
SR- 99 SR- 99 US- 50 US- 50 I- 80 I- 80 ALL LANES
AM PM AM PM AM PM = PK DIR
NB SB WB EB WB EB = WB& EB
HOV LANE ( Pk Hr, Pk Dir)
TIME SAVED ( Minutes over Lane Length)
HOV TIME SAVINGS
Average Savings 6.4 minutes
Figure 3.10 HOV Lane Time Savings ( Peak Hour, Peak Direction)
Caltrans District Three HOV Lanes
The HOV Systems Manual ( NCHRP Report 414) suggests that a savings goal of five minutes per trip,
and/ or one minute per lane mile, be used to gauge the success of HOV lane operations. As shown in
Figure 3.10, the only HOV lane in District Three that does not meet the 5- minute criterion is the
eastbound leg of I- 80 during the evening peak. The HOV lane along this segment was opened in
October 2003 by adding a lane to the five- lane freeway, and the added lane reduced congestion
enough so that the HOV lane offered little time advantage. This situation can be expected to change
over time as congestion increases. The average time savings for all District Three HOV lanes during
the 2003/ 04 time frame was 6.4 minutes, or 0.54 minutes per HOV lane mile.
Violation Rates. Figure 3.11 plots the average violation rates recorded on District Three’s HOV
lanes for the year 2003 ( 2004 for I- 80). In this case the violation rate is defined as the percentage of
vehicles in the lane that fail to meet the minimum occupancy requirement.
3- 12
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
SR- 99 SR- 99 US- 50 US- 50 I- 80 I- 80 ALL LANES
AM PM AM PM AM PM = PK DIR
NB SB WB EB WB EB = WB& EB
HOV LANE ( Pk Hr, Pk Dir)
PEAK PERIOD VIOLATION RATE
% VIOLATION RATE
Average: 10.15%
Figure 3.11 Violation Rates Per Lane
Caltrans District Three ( 2003/ 04)
The average violation rate was 10.15%, right at the 10% rate identified in past studies ( for example,
Billheimer, 1990) as a threshold for concern.
3.2.6 District Three Summary
The percentage of carpoolers in the freeway corridors served by each of District Three’s HOV lanes
has increased steadily, along with vehicle occupancy rates, following the introduction of the
preferential lanes. The HOV lanes in service the longest, those on SR- 99 are well utilized during
peak commute periods and the most recently installed lanes, on US- 50 and I- 80, meet or exceed the
minimum service criteria of 800 vehicles per hour established by the state.
For the most part, there is no way of knowing whether the measured increases in carpooling on
District Three’s mainline HOV lanes came from newly formed carpools or existing carpools which
changed routes to take advantage of improved travel times. As time goes on, the question of whether
the carpools added to the freeway mix following the introduction of HOV lanes were new or diverted
becomes less and less important, since evidence from both Northern and Southern California surveys
suggests that, over time, HOV lanes cause carpools to last longer, regardless of how those carpools
came to be in the lanes in the first place.
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3.3 DISTRICT FOUR
3.3.1 System Map
CALTRANS District Four comprises nine counties in the San Francisco Bay Area. As of December,
2003, the area had 318.5 directional miles of HOV lanes, including
• 279.3 directional miles of exclusive freeway lanes reserved for vehicles with two or more
( 2+) occupants;
• 31.4 directional miles of exclusive freeway lanes reserved for vehicles with three or more
( 3+) occupants;
• 7.8 directional miles of exclusive freeway lanes leading to four bridge toll plazas:
- The San Francisco/ Oakland Bay Bridge ( ALA- 80, 3+);
- The Dumbarton Bridge ( ALA- 84, 2+);
- The San Mateo Bridge ( ALA- 92, 2+); and
- The Carquinez Straits Bridge ( SOL- 80, 3+);
This network of HOV lanes is supported by a variety of exclusive connectors and feeder lanes,
including
• Four freeway- to- freeway connectors;
• Two HOV- only freeway on- ramps; and
• Sixty- six HOV bypass lanes at metered freeway on- ramps
A map of existing HOV freeway routes appears in Figure 3.12.
3.3.2 HOV Freeway Inventory
Current Information. Appendix D contains an inventory of HOV freeway lanes in District Four.
The inventory, assembled from data in the most recent ( December 2003) District Four HOV Report,
lists routes and lane miles by direction, along with occupancy requirements, operating hours, opening
dates, and dates and descriptions of subsequent modifications.
Data Availability. As of December, 2004, District Four had produced detailed annual reports on
portions of the HOV system for the years 1987 through 2003. In general, ample data generally exists
documenting HOV lane operations following implementation for these years. Unfortunately, records
documenting corridor operations prior to lane installation are relatively rare. In preparing this report,
“ Before/ After” data summaries were located only for the HOV lanes on SCL- 101, SCL- 237, and
SCL- 280.
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Source: District Four HOV Report, December, 2003
Figure 3.12 Map Of District Four HOV Freeway Lanes
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3.3.3 Historical System Performance
The following charts document various aspects of the year- by- year performance of the HOV lanes in
CALTRANS District Four from their inception to 2003.
Figure 3.13 Vehicles/ Hour On All Bay Area HOV Lanes
Growth of Volume and Capacity. Figure 3.13 plots peak hour, peak direction flow on all Bay Area
HOV lanes as capacity has been added to the freeway network over time. The addition of lanes has
been charted through two indices of capacity: A minimum capacity of 800 vehicles/ hour, generally
recognized as the minimum operating standard for a mature lane ( HOV Systems Manual, NCHRP
Report 414), and a maximum capacity of 1650 vehicles per hour, at which point free- flow operations
begin to deteriorate. Beginning with two bus/ carpool lanes on the westbound Bay Bridge approach,
which opened in December, 1971, the number of HOV freeway lanes and the associated capacity has
increased steadily, nearly doubling in 1990 and 1991 with the opening of a fourth HOV lane on the
bay Bridge approach, the San Mateo Bridge bus/ carpool lane, and HOV lanes on Santa Clara ( SCL)-
85, SCL- 280, Alameda ( ALA)- 880, and San Mateo ( SM)- 101.
The total peak- hour, peak- direction traffic flow increased steadily as the number of HOV lanes
increased, peaking at 16,260 vehicles per hour ( an average of 1,017 vehicles per hour per lane) before
dropping to 15,230 vehicles per hour in 2003. The average flow per lane exceeded the minimum
threshold of 800 vehicles per hour in 1997 and currently averages 958 vehicles per hour on all Bay
Area HOV lanes.
Although promising, the increase in vehicle flow depicted in Figure 3.13 need not reflect a shift in
mode choice on the part of Bay Area drivers. It could be caused by a number of other factors,
including population growth, route shifts by existing carpools, or the realization of latent demand as
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capacity is added to the freeway network. In order to explore the impact of the HOV lanes on carpool
formation and mode choice, it is necessary to trace the incidence of carpooling on the affected
freeways over time.
Incidence of Ridesharing. This section traces the percentage of carpool- eligible persons using Bay
Area bridges and freeways following the introduction of HOV lanes. Carpool eligibility is defined
with respect to the occupancy requirements of the individual lanes, and all eligible persons on the
bridge or freeway are counted, whether or not they are observed using the HOV lanes.
Figure 3.14 charts the incidence of ridesharing over time on the HOV lanes at the toll plazas of three
Bay Area bridges: The Bay Bridge, the San Mateo Bridge, and the Dumbarton Bridge.
Figure 3.14 Percent Ridesharing Persons On Bay Area Bridges
Bay Bridge Ridesharing. The Bay Bridge HOV lanes were opened to 3+ carpools in December
1971. Since that time, the percentage of persons carpooling across the bridge during the morning
peak has risen steadily from 9.1% of all commuters in 1970 to 36.7% of all commuters in 2003, with
a slight drop following the 1989 earthquake, which shut down bridge operations for a month between
October 17 and November 18. At the same time, since the introduction of BART in 1972, the
incidence of bus riders has fallen precipitously, from 47.4% of all bridge commuters in 1970 to 14.1%
in 2004. The BART- induced drop in bus riders has offset the growth in carpooling, so that the net
percentage of ridesharers using the bridge HOV lanes has fallen from 56.5% to 50.8% since the
introduction of the HOV lanes.
PERCENT RIDESHARING PERSONS ON BAY AREA BRIDGES
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
BEFORE BB
HOV
70
75 80 85 90 95 OO
YEAR
PERCENT RIDESHARERS
BAY BRIDGE RIDESHARERS
BAY BRIDGE BUS RIDERS
BAY BRIDGE CARPOOLERS
DUMBARTON BRIDGE RIDESHARERS
SAN MATEO BRIDGE RIDESHARERS
3+ OCC ON ALL BRIDGE HOV LANES 2+ OCC ON SM & DUMBARTON
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Dumbarton Bridge Ridesharing. HOV lanes on the Dumbarton Bridge were opened in October
1982. The percentage of legitimate carpoolers using the bridge HOV lanes rose to 30.8% following
the reduction in occupancy requirements from 3+ to 2+ in January 1992 and has continued to rise,
exceeding 50% of all commuters in 1997 and 2001 before dropping to 42.8% in 2003. This drop
coincided with the completion of construction work on the San Mateo Bridge, which reduced delays
at the toll plaza of the parallel bridge and undoubtedly drew some traffic away from the Dumbarton
Bridge.
San Mateo Bridge Ridesharing. HOV lanes were introduced on the San Mateo Bridge in October
1989. As on the Dumbarton Bridge, the percentage of legitimate carpoolers rose to 30.8% of all
commuters when restrictions were relaxed from 3+ to 2+ in January 1992, and has continued to rise,
reaching 43.9% in 2003.
Thus the introduction of HOV lanes at the toll plazas of the three Bay Area bridges has led to a steady
increase in the percentage of carpooling commuters crossing the bridges. Since the nature of the
bridges effectively precludes the shifting of existing carpools from adjacent routes, it can be assumed
that these increases represent either the formation of new carpools or an extension of the expected life
of those carpools using the bridges.
Figure 3.15 Percent Carpool- Eligible Persons On Contra Costa County Freeways
Ridesharing on Contra Costa County HOV Lanes. Figure 3.15 charts the incidence of carpooling
over time on the HOV lanes on the following three Contra Costa County Freeways: CC- 04, CC- 80,
and CC- 680. Although no “ Before” data are available to document the presence of carpoolers in the
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affected Contra Costa county corridors prior to the introduction of HOV lanes, the chart shows that
the proportion of carpoolers on all tree freeways increased markedly following the introduction of
HOV lanes. On CC- 680, the percentage of carpoolers rose from 19.2% to 30.8% between the
introduction of HOV lanes in 1994 and 2003. Carpool percentages on CC- 80 increased from 29.3%
in 1997, the first year of HOV lane operations, to 43.8% in 2003. Similarly, the proportion of
carpoolers using CC- 04 has increased from 32.3% to 47.6 % over the life of the HOV lanes.
Ridesharing on Santa Clara County HOV Lanes. Figure 3.16 charts the incidence of carpooling
over time on the HOV lanes on the following four Santa Clara County Freeways: SCL- 85, SCL- 101,
SCL- 237, and SCL- 280.
Figure 3.16 Ridesharing Over Time On Santa Clara County HOV Lanes
On all but one of the four Santa Clara County HOV lanes, the percentage of people eligible for the 2+
carpool lanes increased following the introduction of the lanes. On SCL- 101, the percentage of
carpoolers in the corridor increased from 24.9% prior to the opening of the first segment of HOV
lanes in November 1986 to 36.4% in 2003. The proportion of carpoolers on SCL- 85 rose from 15.0%
when the lanes first opened in 1990 to 31.4% in 2003. While carpoolers represented just 24.2% of the
morning commuters using the SCL- 280 corridor prior to the opening of HOV lanes in December
1990, by 2003 this proportion had increased to 29.0%.
The SCL- 237 corridor represents one of the only Bay Area corridors where the proportion of
carpoolers has dropped following the introduction of HOV lanes. In 1984, before HOV lanes were
installed on the SCL- 237 expressway, 31.4% of the commuters in the corridor qualified as carpoolers.
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This percentage had risen to 41.7% by 1994, but then began dropping when SCL- 237 was upgraded
to a freeway in 1995. By 2003, the percentage of carpoolers had dropped to 27.3%, below the
1984pre- HOV level. Two factors may account for this drop: When SCL- 237 was upgraded to
freeway status, the number of buses using the route dropped somewhat, and the corridor serves the
heart of Silicon Valley, and therefore was affected by the drastic employment drop accompanying the
business decline in 2000.
3.3.4 Current System Performance
The following charts offer lane- by- lane comparisons of such key performance measures as vehicle
volumes, occupancies, travel time savings, and violation rates for the most recent year available,
2003.
Peak- Hour Traffic Volumes. Recent vehicle volumes on District Four’s HOV lanes are graphed in
Figure 3.17, which shows peak- hour volumes in the peak direction of morning and evening flow.
0
200
400
600
800
1000
1200
1400
1600
1800
ALA- 80
BAY BR
ALA- 80
ALA- 80
ALA- 84
DUM BR
ALA- 92
SM BR
ALA- 880
ALA- 880
CC- 4
CC- 4
CC- 80
CC- 80
CC- 680
CC- 680
MRN- 101
MRN- 101
MRN- 101
M