Division of Research
& Innovation
Report CA04- 0494
December 2008
Assessment of the Applicability of Cooperative
Vehicle- Highway Automation Systems
( CVHAS) to Bus Transit and Intermodal
Freight:
Case Study Feasibility Analyses in the
Metropolitan Chicago Region
Final Report
Assessment of the Applicability of Cooperative
Vehicle- Highway Automation Systems ( CVHAS)
to Bus Transit and Intermodal Freight:
Case Study Feasibility Analyses in the
Metropolitan Chicago Region
Final Report
Report No. CA04- 0494
December 2008
Prepared By:
University of California PATH
Richmond Field Station, Bldg. 452
1357 South 46th Street
Richmond, CA 94804
Prepared For:
California Department of Transportation
Division of Research and Innovation, MS- 83
1227 O Street
Sacramento, CA 95814
DISCLAIMER STATEMENT
This document is disseminated in the interest of information exchange. The contents of this report
reflect the views of the authors who are responsible for the facts and accuracy of the data presented
herein. The contents do not necessarily reflect the official views or policies of the State of California
or the Federal Highway Administration. This publication does not constitute a standard,
specification or regulation. This report does not constitute an endorsement by the Department of
any product described herein.
STATE OF CALIFORNIA DEPARTMENT OF TRANSPORTATION
TECHNICAL REPORT DOCUMENTATION PAGE
TR0003 ( REV. 10/ 98)
1. REPORT NUMBER
CA04- 0494
2. GOVERNMENT ASSOCIATION NUMBER
3. RECIPIENT’S CATALOG NUMBER
5. REPORT DATE
August, 2004
4. TITLE AND SUBTITLE
Assessment of the Applicability of Cooperative Vehicle- Highway
Automation Systems ( CVHAS) to Bus Transit and Intermodal Freight:
Case Study Feasibility Analyses in the Metropolitan Chicago Region
6. PERFORMING ORGANIZATION CODE
7. AUTHOR( S)
Steven Shladover
8. PERFORMING ORGANIZATION REPORT NO.
UCB- ITS- PRR- 2004- 26
10. WORK UNIT NUMBER
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of California PATH, Richmond Field Station, Bldg. 452
1357 South 46th Street
Richmond, CA 94804- 4698
11. CONTRACT OR GRANT NUMBER
65A0071
13. TYPE OF REPORT AND PERIOD COVERED
Final Report, Task Order # 4401
12. SPONSORING AGENCY AND ADDRESS
California Department of Transportation
Division of Research and Innovation, MS- 83
1227 O Street Sacramento CA 95814
14. SPONSORING AGENCY CODE
15. SUPPLEMENTAL NOTES
16. ABSTRACT
This report presents the results of its performance assessment of the feasibility of applying cooperative vehicle-highway
automation systems ( CVHAS) to bus transit and freight movements in the metropolitan Chicago area.
CVHAS are systems that provide driving control assistance or fully automated driving and are based on
information about the vehicle's driving environment that can be received by communication from other vehicles
or from the infrastructure, as well as from their own on- board sensors. The Chicago Central Area is equipped
with rail transit, commuter rail and bus transit service, however, the connections between the commuter rail
stations and major destinations, especially across town, are not as good as they should be. Bus Rapid Transit
( BRT) systems making use of CVHAS technologies have promise to help improve connectivity within the
Chicago Central Area. Three BRT case studies were performed in which CVHAS technologies were evaluated,
including transit signal priority, collision warning, precision docking and automatic steering control systems. A
total of five operational concept alternatives were selected. The evaluation showed that all of the alternatives are
economically feasible and CVHAS technologies are able to help improve the performance of the intermodal
freight system. One of the alternatives was recommended for further investigation, in which conventional truck-only
facilities open to all trucks before 2015 and then upgraded to an automated highway open only to
automated trucks. These preliminary case studies have shown potentially significant benefits from use of
CVHAS technologies to help solve specific problems for bus and truck transportation in the Chicago region.
Although the case study examples are specific to Chicago, they indicate the potential that these technologies
should have for use in other major metropolitan areas as well. Within the Chicago context, they should also
stimulate follow- on studies to explore the design and deployment issues in more depth so that progress can be
made toward the start of implementation.
17. KEY WORDS
Cooperative vehicle highway automation
systems, bus rapid transit, intermodal
freight, heavy trucks
18. DISTRIBUTION STATEMENT
No restrictions. This document is available to the
public through the National Technical Information
Service, Springfield, VA 22161
19. SECURITY CLASSIFICATION ( of this report)
Unclassified
20. NUMBER OF PAGES
192
21. PRICE
Reproduction of completed page authorized
ISSN 1055- 1425
August 2004
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 4401
CALIFORNIA PATH PROGRAM
INSTITUTE OF TRANSPORTATION STUDIES
UNIVERSITY OF CALIFORNIA, BERKELEY
Assessment of the Applicability of Cooperative Vehicle- Highway
Automation Systems to Bus Transit and Intermodal Freight: Case
Study Feasibility Analyses in the Metropolitan Chicago Region
UCB- ITS- PRR- 2004- 26
California PATH Research Report
Steven E. Shladover ( Principal Investigator), Mark A. Miller, Yafeng Yin, Tunde Balvanyos,
Lauren Bernheim, Stefanie R. Fishman
California PATH Program, University of California, Berkeley
Farid Amirouche ( Principal Investigator), Khurran T. Mahmudi, Pedro Gonzalez- Mohino, Joseph Solomon
University of Illinois, Chicago
Gerald Rawling, Ariel Iris, Claire Bozic
Chicago Area Transportation Study
CALIFORNIA PARTNERS FOR ADVANCED TRANSIT AND HIGHWAYS
Assessment of the Applicability of Cooperative
Vehicle- Highway Automation Systems to Bus Transit
and Intermodal Freight:
Case Study Feasibility Analyses in the Metropolitan
Chicago Region
California PATH Program
University of California at Berkeley,
The University of Illinois at Chicago, and
The Chicago Area Transportation Study
August 19, 2004
i
ACKNOWLEDGEMENTS
This work was performed by the California PATH Program at the University of California at
Berkeley, the University of Illinois at Chicago, and the Chicago Area Transportation Study
( CATS) as part of the Cooperative Vehicle- Highway Automation Systems ( CVHAS) Program
Pooled Fund Study in cooperation with the State of California Business, Transportation and
Housing Agency, Department of Transportation. The contents of this paper reflect the views of
the authors, who are responsible for the facts and the accuracy of the data presented herein. The
authors, by organization, are listed below. The contents do not necessarily reflect the official
views or policies of the State of California or the CVHAS Program Pooled Fund Study.
The authors thank David Zavattero of the Illinois Department of Transportation and member of
the Pooled Fund Study Policy Steering Committee and each member of the Bus Transit and
Intermodal Freight Stakeholder Advisory Committees for their support during this project. The
authors acknowledge Greg Larson and Pete Hansra of the California Department of
Transportation’s ( Caltrans’) Division of Research and Innovation for their support of this
project.
Author List
University of California, Berkeley:
Steven E. Shladover ( Principal Investigator)
Mark A. Miller
Yafeng Yin
Tunde Balvanyos
Lauren Bernheim
Stefanie R. Fishman
University of Illinois, Chicago:
Farid Amirouche ( Principal Investigator)
Khurram T. Mahmudi
Pedro Gonzalez- Mohino
Joseph Solomon
Chicago Area Transportation Study:
Gerald Rawling
Ariel Iris
Claire Bozic
ii
ABSTRACT
This report presents the results of its performance assessment of the feasibility of applying
cooperative vehicle- highway automation systems ( CVHAS) to bus transit and freight movements
in the metropolitan Chicago area. Cooperative vehicle- highway automation systems are systems
that provide driving control assistance or fully automated driving and are based on information
about the vehicle's driving environment that can be received by communication from other
vehicles or from the infrastructure, as well as from their own on- board sensors.
The Chicago Central Area is equipped with rail transit, commuter rail and bus transit service,
however, the connections between the commuter rail stations and major destinations, especially
across town, are not as good as they should be. Bus Rapid Transit ( BRT) systems making use of
CVHAS technologies have promise to help improve connectivity within the Chicago Central
Area. Three BRT case studies were performed in which CVHAS technologies were evaluated,
including transit signal priority, collision warning, precision docking and automatic steering
control systems. For these evaluations there is a nearly universal ability for each CVHAS
application ( except for collision warning systems) to pay for the system with minimal time
savings required and there are consistently large to very large B/ C ratios across CVHAS
applications accounting for uncertainty in parameter values and lack of complete data. For
collision warning systems, there is not a strong economic case for or against the deployment of
these systems. However, even a small number of serious crashes here could tilt the balance
significantly in favor of deployment of systems that could avoid or mitigate those crashes.
For intermodal freight, a new truck- only facility is proposed and based on available rail rights-of-
way, to serve a selected set of intermodal rail yards, industrial parks and points- of- entry to the
region. A total of five operational concept alternatives were selected, including a baseline,
against which to measure the impacts of CVHAS technology applications and by performing
comparative analyses against the baseline calculating both benefits and costs. The evaluation
showed that all of the alternatives are economically feasible and CVHAS technologies are able
to help improve the performance of the intermodal freight system. One of the alternatives was
recommended for further investigation, in which a conventional truck- only facility open to all
trucks before 2015 and then upgraded to an automated highway open only to automated trucks.
These preliminary case studies have shown potentially significant benefits from use of CVHAS
technologies to help solve specific problems for bus and truck transportation in the Chicago
region. Although the case study examples are specific to Chicago, they indicate the potential
that these technologies should have for use in other major metropolitan areas as well. Within the
Chicago context, they should also stimulate follow- on studies to explore the design and
deployment issues in more depth so that progress can be made toward the start of
implementation.
Key Words: cooperative vehicle highway automation systems, bus rapid transit, intermodal
freight, heavy trucks
iii
EXECUTIVE SUMMARY
This report summarizes the research that has been done to determine how Cooperative Vehicle-
Highway Automation Systems ( CVHAS) could enhance the performance of Bus Rapid Transit
and heavy truck systems in a major urban region. Using a case study approach to address
specific transportation problems faced by the Chicago region, this report provides an indication
of the types of benefits that can be gained by use of CVHAS technologies as alternatives to
conventional transportation technologies.
The CVHAS technologies that have been evaluated here include:
- Transit signal priority ( TSP) to speed up the movement of buses in dense urban traffic;
- Collision warning systems to help bus or truck drivers avoid crashes;
- Precision docking to facilitate easy boarding and alighting of transit bus passengers;
- Automatic steering control to enable buses and trucks to drive in very narrow lanes;
- automatic speed and spacing control to enable buses or trucks to follow other vehicles of the
same type at short spacings, increasing the capacity of a roadway lane;
- fully automated operation, combining the steering control with speed and spacing control.
The case studies have been conducted to make sure that these technologies are not viewed as
ends in themselves, but rather are used to help solve specific transportation problems. The case
studies were directed at two different operating environments, each with its own special needs:
Bus Rapid Transit for the Chicago Central Area
The Chicago Central Area is already heavily equipped with rail transit, commuter rail and bus
transit service, but the connections between the commuter rail stations and major destinations,
especially across town, are not as good as they should be. Bus Rapid Transit ( BRT) systems
making use of CVHAS technology appear to have promise for helping to improve connectivity
within the Chicago Central Area, particularly for service needs that were identified in the recent
Chicago Central Area Plan ( cross- town service across the Loop area, and service between the
commuter rail stations to the west of the Loop and the Navy Pier and nearby growing
neighborhoods to the northeast). The CVHAS technologies that were evaluated for BRT use
were traffic signal priority, collision warning, precision docking and automatic steering control.
Improving Access for Freight Movement to and from Intermodal Rail Terminals, Warehouse and
Industrial Concentrations and Highway Points of Entry to the Region
Chicago is the rail freight hub of the nation and the primary junction between the major railroads
that serve the eastern and western halves of the North American continent. The connections
among the intermodal rail terminals, the local warehouse and industrial concentrations and the
highway points of entry to the Chicago region are impeded by difficult road access, involving
highly congested highways and much travel on local streets that are not really suitable for high
volumes of heavy truck traffic. This has adverse effects on the efficiency of freight movement,
as well as creating additional traffic, noise and pollution impacts on all the residents and
travelers who must coexist with the heavy truck traffic. These problems could be ameliorated by
implementation of a truck- only roadway connecting many of the most important freight
iv
movement nodes in the region, primarily by use of currently under- utilized former railroad rights
of way, either adjacent to existing tracks or in air rights. The CVHAS technologies that were
evaluated for use on the truck- only roadway were automatic steering control, automatic speed
and spacing control, and fully automated driving.
The results of these case studies are summarized below.
1. Bus Rapid Transit Applications of CVHAS
1.1 Collision Warning Systems
These were evaluated for near- term use on the cross- town routes that currently operate on major
one- way street pairs in the Loop Area. Recent crash data for bus operations in this area from the
Chicago Transit Authority were reviewed to identify the crash problems that are currently
encountered. These were then evaluated based on the potential that forward, side and rear
collision warning systems have to help drivers avoid these crashes. The frequency and severity
of bus crashes in the Loop Area are relatively low, particularly with the low prevailing traffic
speeds, and their costs to CTA appear to be in the same general range as the costs of
implementing the collision warning systems, considering the uncertainties in the available data.
This means that there is not a strong economic case for or against the deployment of these
systems. However, even a small number of serious crashes here could tilt the balance
significantly in favor of deployment of systems that could avoid or mitigate those crashes.
1.2 Precision Docking
Precision docking was also evaluated for near- term use on the cross- town routes in the Loop
Area. Precision docking has two different types of benefits, only one of which is susceptible to
quantitative analysis. The first benefit is the enhanced quality of service to passengers, which
provides a relatively intangible benefit that could eventually be translated into increases in
ridership and favorable image. The more quantifiable benefit is in the reduction of bus stop
dwell times by making it easier for passengers to board and alight the buses, especially those
with mobility challenges. This can provide operating cost savings to the transit operator and
time savings to the passengers. In the absence of definitive data about the time savings that can
actually be gained from this new technology, the analysis was able to show that the economic
break- even point for the transit operator could be achieved even if docking saved an average of
only 2.52 seconds per bus stop, and if the value of time for an average of 20 passengers per bus
was factored into the analysis, a time saving of only 0.73 seconds per stop would still produce
net benefits. If docking could save as much as 5 seconds per bus stop, the benefit/ cost ratio
would be 4.4, even with an average bus occupancy of only 10 passengers. Longer time savings
could of course produce even higher B/ C ratios.
1.3 Transit Signal Priority
Transit signal priority ( TSP) was also evaluated on the Loop cross- town routes, to determine its
advantages in reducing the delays that buses experience at traffic signals. Thus the focus of this
evaluation was on the benefits of TSP for the transit operator by reducing its overall operating
v
costs and for bus passengers by reducing their total travel time. The analysis of TSP indicated
that if would break even for the transit operator if it was able to save each cross- town Loop bus
an average of only 7 seconds on a round trip across the Loop that currently takes an average of
15 to 20 minutes. When the travel time savings of the bus passengers are factored in, the break-even
time saving is reduced to 3 seconds with an average of ten passengers per bus or 2 seconds
with 20 passengers per bus. Preliminary analyses indicate the possibility that the actual time
savings could be in the range of 42 seconds, which would produce B/ C ratios of 14 to 21 with
average passenger loads to 10 to 20 people.
1.4 Automatic Steering Control
In the long term, the Chicago Central Area Plan includes provisions for an underground busway
to provide cross- town bus service beneath Monroe Street. Application of automatic steering
control on the buses that operate there would make it possible to reduce the width of two lanes of
busway from twelve feet to ten feet each. This saving of four feet of busway width could
represent a significant saving in the cost of constructing the underground facility. Tunnel
construction experts were reluctant to specify the costs of construction without detailed soils and
engineering studies, but a break- even analysis showed that the automatic steering control would
pay for itself even if the tunnel construction costs were as low as $ 25 per square foot ( many
times less than contemporary residential housing construction costs, and in all likelihood orders
of magnitude lower than current urban tunnel construction costs). Even if the tunnel
construction costs were to be one- third of the cost per square foot of the Seattle bus tunnel, the
B/ C ratio for automatic steering control would still be about 20.
The Chicago Central Area Plan also calls for a new busway on former railroad right of way
along Carroll Avenue, just north of the Loop area. This busway would require construction of a
new bridge over the north branch of the Chicago River, another location where the automatic
steering of the buses could save four feet of lane width. That width reduction would reduce the
cost of the bridge by more than $ 2 million, which by itself would provide a B/ C ratio in excess
of 22 for the automatic steering capability to be installed on all the buses using the busway.
Another planned underground section of this busway, along Clinton, could produce an even
larger cost saving because of the reduction in the busway width.
2. Heavy Truck Applications of CVHAS
The heavy truck applications of CVHAS were evaluated based on a hypothesized new truck- only
roadway facility that would be built to connect several of the most important intermodal rail
terminals, primarily on the south side of downtown Chicago, with additional connections to I- 90
at the Indiana State Line and I- 294 on the northwest side of Chicago. As part of this project,
both near- term and long- term alignments were defined for this new truck roadway, in
consultation with the freight movement staff at CATS, the regional MPO.
The case study analysis had to begin with evaluating the effectiveness of the new truck- only
roadway without any CVHAS technologies, since this was not part of any previous study and
had not even been designed before. The truck- only roadway was found to have significant
benefits in reducing delays to truck traffic, as well as relieving the congestion imposed on other
vi
traffic by the trucks that currently need to use the regular highways in the region ( B/ C ratio 3.63
compared to do- nothing alternative). The more interesting part of the study was in exploring
what the additional effects would be of applying CVHAS technologies to the trucks using the
new facility.
The primary advantage of automatic steering control of the trucks is in reducing the width of
lanes needed for the new truck facility, and hence their construction and right- of- way costs.
However, in order to gain this cost- saving advantage, it would be necessary for the truck facility
to be restricted to trucks with automatic steering ( because drivers would not be able to steer their
conventional trucks accurately enough to use the narrower lanes). That introduced a deployment
staging challenge, because not enough trucks would be equipped with the automatic steering
capability in the early years of operation of the truck facility, and it would be under- utilized until
the population of equipped trucks increased significantly ( and the costs of the technology
declined significantly from its initial costs). This under- utilization of the new automated- truck-only
facility made it less cost- effective than a full- width truck- only facility that would be open to
all trucks, without any use of the CVHAS technology ( B/ C ratio of 3.27).
Automatic speed and spacing control of trucks makes it possible for them to operate in close-formation
platoons of up to three trucks. In this way, a single roadway lane can accommodate
about twice the volume of trucks as a conventional- technology truck lane. This means that in
future years, as the volume of truck traffic grows, it will not be necessary to add lanes for the
additional trucks, thereby saving considerable capital construction and right of way costs. In
addition, the close- formation platoon operations reduce aerodynamic drag, saving significant
fuel costs and reducing pollution emissions as well. Indeed, the evaluation scenarios that include
automatic speed and spacing control show significant capital cost savings by avoiding the need
of the construction of an additional lane in each direction as traffic grows. However, when these
are based on use only by CVHAS- equipped trucks right from the start, the under- utilization of
the truck facility in the early years reduces the B/ C ratio below the B/ C ratio for the
conventional- technology truck lane system ( B/ C ratio of 2.45).
The most beneficial alternative for use of CVHAS technologies on the new truck facility
involves deferring the implementation of the CVHAS technologies until after the facility has
been in operation for a while and the costs of the vehicle technologies have declined. In this
case, a single- lane ( each way) truck facility would be opened to use by all trucks in the near term
( as soon as it could be constructed), and then as the volume of truck traffic and of CVHAS-capable
truck grows over time, it would be converted to automated operation in the longer term
( perhaps year 2015). With this scenario, the utilization of the new facility is relatively high from
the start, and the benefits of the capacity increase from the speed and spacing control technology
are gained in the later years, when they are most needed. This mixed solution showed the
highest B/ C ratio by a substantial margin, 5.15. The automatic steering technology could be
used in concert with the speed and spacing control technology to provide fully automated driving
in those later years, but the additional benefits of that would be more associated with driving
comfort and convenience because the lanes would have already been constructed to full width.
When this project began, the participants assumed that the dominant market need for heavy truck
accessibility in the Chicago region was for rubber- tired cross- town transfers between intermodal
vii
rail terminals, as it had been twenty years previously. However, in the course of work on the
project it became evident, through the insights of the CATS staff, that this is actually a shrinking
( though not vanishing) segment of the Chicago trucking market. Increasing percentages of these
transfers are now being handled by rail, while the more significant growth in demand is for
linkages to and from the major highway points of entry to the region and the local industrial and
warehousing concentrations. Therefore, this broader market has been addressed in the study,
even though the networks of truck lanes that we have been conceptualizing are largely
concentrated on serving the major intermodal rail terminals, reflecting the initial scope and focus
of the study. It would be worthwhile to pursue an additional study addressing the full range of
regional truck accessibility needs from the start, and considering the opportunities for developing
truck lanes, both with and without CVHAS technologies, in other parts of the Chicago region,
unconstrained by the locations of intermodal terminals and railroad rights of way.
Conclusions
These preliminary case studies have shown potentially significant benefits from use of CVHAS
technologies to help solve specific problems for bus and truck transportation in the Chicago
region. Although the case study examples are specific to Chicago, they indicate the potential
that these technologies should have for use in other major metropolitan areas as well. Within the
Chicago context, they should also stimulate follow- on studies to explore the design and
deployment issues in more depth so that progress can be made toward the start of
implementation.
viii
TABLE OF CONTENTS
SECTION PAGE
ACKNOWLEDGEMENTS i
ABSTRACT ii
EXECUTIVE SUMMARY iii
LIST OF TABLES xi
LIST OF FIGURES xiv
1.0 PROJECT OVERVIEW 1
2.0 COOPERATIVE VEHICLE- HIGHWAY AUTOMATION SYSTEMS
( CVHAS) 3
2.1 CVHAS Attributes 3
2.1.1 CVHAS Opportunities in These Case Study Projects 5
2.1.2 CVHAS Benefit Opportunities 6
2.1.3 Incremental Cost Generators 7
2.2 Applicability of CVHAS Technologies Based on Right- of- Way Restrictions 8
3.0 BUS TRANSIT SYSTEMS IN TH LOOP AREA OF CHICAGO 11
3.1 Background Information 11
3.1.1 Central Area Circulator Project 11
3.1.2 Carroll Avenue Busway Study 15
3.1.3 Chicago Central Area Plan 16
3.2 Selection of Case Study Alignments 20
3.3 Method Applied in Case Studies 22
3.4 East- West At- Grade  Near- Term Case Study 23
3.4.1 Case Study Corridor 23
3.4.2 Evaluation of Near- Term East- West Alternatives in the Loop 29
3.4.2.1 Collision Warning Systems 29
3.4.2.2 Precision Docking 33
3.4.2.3 Transit Signal Priority 37
3.5 East- West Underground Monroe Busway  Long- Term Case Study 41
3.5.1 Case Study Corridor 42
3.5.2 Evaluation of Long- Term Underground Monroe Busway 45
3.5.2.1 Precision Docking 45
3.5.2.2 Reduction of Lane Width 47
3.6 Clinton- Carroll Avenue Busway  Long- Term Alternative 49
3.6.1 Case Study Corridor 49
3.6.1.1 Clinton Underground Bus Tunnel 50
3.6.1.2 Carroll Avenue Busway 50
3.6.2 Evaluation of Long- Term Clinton- Carroll Avenue Busway 53
3.7 Conclusions 55
3.7.1 Summary of Major Findings 55
ix
SECTION PAGE
3.7.2 Recommendations and Next Steps 56
3.8 References 57
4.0 FREIGHT MOVEMENTS 59
4.1 Background Information 59
4.2 Selection of Alignment 61
4.2.1 Identification of Nodes 61
4.2.1.1 Choice of Yards 62
4.2.1.2 Choice of Points of Entry 63
4.2.1.3 Choice of Industrial Parks/ Warehouse Concentrations 64
4.2.2 Node- Link Combinations 64
4.2.2.1 Short- Term Alignment 64
4.2.2.2 Long- Term Alignment 67
4.3 Concept of Operations 68
4.3.1 Operational Concept Designs 68
4.3.2 Recommended Alternative Operational Concepts 72
4.4 Methodology 72
4.5 Data Needs and Sources 73
4.6 Impact Analysis 74
4.6.1 Traffic Impacts 74
4.6.2 Safety Impacts 80
4.6.3 Fuel Consumption/ Emissions Impacts 80
4.7 Cost- Benefit Analysis 81
4.7.1 Cost Estimation 82
4.7.1.1 Construction Costs 82
4.7.1.2 Right- of- Way Costs 85
4.7.1.3 Annual Operation and Maintenance of Facility Cost 85
4.7.1.4 CVHAS Equipment and Installation Costs ( Facility) 85
4.7.1.5 CVHAS Equipment and Installation Costs ( In- vehicle Unit) 86
4.7.2 Benefit Estimation 89
4.7.2.1 Travel Time Savings 89
4.7.2.2 Reductions in Fuel Consumption 91
4.7.3 Comparison of Costs and Benefits 92
4.7.4 Sensitivity Analyses 93
4.8 Conclusions 96
4.8.1 Summary of Major Findings 96
4.8.2 Recommendations and Next Steps 97
4.9 References 98
APPENDIX I Automation Technologies and Concepts 100
APPENDIX II Present Condition of Carroll Avenue Right- of- Way 112
APPENDIX III Description and Assessment of Field Data Collection for
East- West At- Grade Short- Term Alternative 114
x
SECTION PAGE
APPENDIX IV Right- Of- Way Conditions of Short- Term Alignment 134
APPENDIX V Detailed Alignment Design for Selected Segments 161
xi
LIST OF TABLES PAGE
TABLE 2.1 Applicability of CVHAS Concepts by ROW Restriction 10
TABLE 3.1 CTA Bus Routes on Washington- Madison Streets 25
TABLE 3.2 Frequency of Buses on Washington Avenue During Peak Periods 26
TABLE 3.3 Frequency of Buses on Madison Avenue During Peak Periods 26
TABLE 3.4 CTA Bus Routes on Jackson- Adams Streets 27
TABLE 3.5 Frequency of Buses on Jackson Avenue During Peak Periods 28
TABLE 3.6 Frequency of Buses on Adams Avenue During Peak Periods 28
TABLE 3.7 Distribution of Incident Types in the Loop in 2002 30
TABLE 3.8 Distribution of Incident Types on Four Arterials in the Loop in 2002
After Redistribution and Scaling 31
TABLE 3.9 Distribution of Crashes on Four Arterials in the Loop 32
TABLE 3.10 Net Benefits and B/ C Ratio for Collision Warning Systems 33
TABLE 3.11 Unit Costs of Precision Docking Technologies 35
TABLE 3.12 Time Savings: Annually and Per Bus Stop 36
TABLE 3.13 Savings and Benefit- Cost Ratio Findings: Near- Term Precision
Docking 37
TABLE 3.14 Through Traffic at Intersections in the Loop 38
TABLE 3.15 All Traffic ( Through and Turning) at Intersections in the Loop 39
TABLE 3.16 Time Savings: Annually and Per Bus Round Trip 41
TABLE 3.17 Savings and Benefit- Cost Ratio Findings: Near- Term Transit Signal
Priority 41
TABLE 3.18 Headways for Bus Routes 122 and 123 During Peak Periods 43
xii
LIST OF TABLES PAGE
TABLE 3.19 CTA Bus Routes 122 and 123 During Peak Periods 43
TABLE 3.20 Eastbound Bus Routes During Peak Periods 44
TABLE 3.21 Westbound Bus Routes During Peak Periods 44
TABLE 3.22 Time Savings: Annually and Per Bus Stop 46
TABLE 3.23 Savings and Benefit- Cost Ratio Findings: Long- Term Precision
Docking 47
TABLE 3.24 Savings and Benefit- Cost Ratio Findings: Long- Term Tunnel
Construction 48
TABLE 3.25 Eastbound Bus Routes 120 and 121 During Peak Periods 51
TABLE 3.26 Westbound Bus Routes 120 and 121 During Peak Periods 51
TABLE 4.1 Length of Each Segment in Short Term Alignment 66
TABLE 4.2 Truck Facility Daily Statistics under No- Toll Scenario 76
TABLE 4.3 Network Statistics under No- Toll Scenario 76
TABLE 4.4 Truck Facility Daily Statistics with Toll Scenario 77
TABLE 4.5 Network Statistics with Toll Scenario 77
TABLE 4.6 Predicted Daily Truck Facility Traffic Volumes for Alternatives 3 and 4 78
TABLE 4.7 Automated Truck Lane Capacity 79
TABLE 4.8 Construction Cost Estimation of Truck- Only Facility 84
TABLE 4.9 Total Construction Cost for Each Alternative ( Year 2003 Dollars) 85
TABLE 4.10 Right- of- Way Cost for Each Alternative ( Year 2003 Dollars) 85
TABLE 4.11 CVHAS Facility Cost for Each Alternative ( Year 2003 Dollars) 86
TABLE 4.12 Cost Estimation for In- Vehicle Units 87
xiii
LIST OF TABLES PAGE
TABLE 4.13 CVHAS In- Vehicle Equipment Cost for Each Alternative
( Year 2003 Dollars) 89
TABLE 4.14 Travel Time Savings for Each Alternative ( Year 2003 Dollars) 91
TABLE 4.15 Reduction of Fuel Consumption for Each Alternative,
Compared to Baseline Case with No Truck Facility 92
TABLE 4.16 Evaluation Results of the Alternative Operational Concepts 92
xiv
LIST OF FIGURES PAGE
FIGURE 2.1 CVHAS Technology Characteristics 3
FIGURE 3.1 The Route of the Proposed Light Rail System for the Central Area
Circulator Project 14
FIGURE 3.2 Carroll Avenue Busway 16
FIGURE 3.3 A Future East- West Busway on Adams Street 17
FIGURE 3.4: A Future East- West Busway under Monroe Street 17
FIGURE 3.5 Top View of Proposed Monroe Busway 18
FIGURE 3.6: Monroe Busway Docking Stations 19
FIGURE 3.7 Front View of Proposed Monroe Busway 20
FIGURE 3.8 Routes in Downtown Chicago Potentially Benefiting from CVHAS
Technologies in the Near- Term 21
FIGURE 3.9 Routes in Downtown Chicago Potentially Benefiting from CVHAS
Technologies in the Long- Term 22
FIGURE 3.10 Three Bus Transit Case Study Corridors 23
FIGURE 3.11 Location for Underground Monroe Busway 42
FIGURE 3.12 Location for Clinton- Carroll Avenue Busway 49
FIGURE 4.1 Northeastern Illinois Freight Interchange System 62
FIGURE 4.2 The Short Term Alignment 65
FIGURE 4.3 The Long- Term Alignment 68
FIGURE 4.4 Fuel Consumption of Trucks 81
FIGURE 4.5 Inflation- Adjusted Cost per Lane Mile for Major Chicago Area
Highway Engineering and Construction Projects 83
FIGURE 4.6 Change of CVHAS Equipped Cost per Vehicle over Time 87
xv
LIST OF FIGURES PAGE
FIGURE 4.7 Assumed Growth of Automatic Steering Equipped Trucks 88
FIGURE 4.8 Assumed Growth of Full Automation Trucks 89
FIGURE 4.9 Actual Time Savings vs. Calculated Savings with Linear Scaling 90
FIGURE 4.10 B/ C Ratios of Alternative 5 Compared to the Do- Nothing Alternative
in the Monte- Carlo Analysis 94
FIGURE 4.11 B/ C Ratios of Alternative 5 Compared to Alternative 2 ( Conventional
Truck Only Facility) in the Monte- Carlo Analysis 96
1
1.0 PROJECT OVERVIEW
The Cooperative Vehicle- Highway Automation Systems ( CVHAS) pooled fund project was
initially proposed by the California Department of Transportation ( Caltrans) and joined by ten
other state departments of transportation, and Honda R& D North America, with the purpose of
promoting progress toward deployment of CVHAS technologies. The sponsoring states decided
that their first projects should be evaluations of the opportunities for implementing CVHAS on
transit buses or heavy trucks to solve transportation problems in specific locations in one or more
of the states. These case study projects were “ fast tracked” in order to take advantage of the
opportunity to present the results to visitors to the demonstration of bus and truck automation
systems that Caltrans and PATH organized in San Diego. ( Eventually, the California state
budget crisis required this demonstration to be scaled back to a low- profile event for a limited
audience, with a focus only on the transit bus application.)
The representatives of the CVHAS states proposed a variety of potential applications for
consideration in the case study projects. After evaluation by the CVHAS Technical Advisory
Committee, the target applications that were chosen were both for the Chicago metropolitan
region.
The proposed transit application was an update of the “ Central Area Circulator Project” study of
a decade ago, but now considering how a Bus Rapid Transit system augmented with CVHAS
technologies could provide connections to major trip generators and the existing commuter rail
and rail transit systems in and near Chicago’s central business district. This application appeared
promising because the prior study had favored light rail transit over buses for reasons of capacity
and operating cost that could potentially be counterbalanced by application of CVHAS to buses.
When the costs of the light rail system grew to be unaffordable in the early 1990s, that project
was abandoned.
The proposed heavy truck application was an update of an intermodal freight terminal connector
study that was done two decades ago, addressing how to provide better transfers among the
many important intermodal terminals in the region by using trucks operating on roadways to be
built on under- utilized rail rights of way. In the case of this study, many significant changes had
occurred since the original study was completed, in issues such as the overall patterns of freight
movements, the utilization of alternative terminals within the Chicago region, and the
availability of right of way, so all of these issues needed to be re- examined, in addition to the
potential for improving operations by use of CVHAS technologies.
The two case study projects were combined in a single contract from Caltrans to the University
of California’s PATH ( Partners for Advanced Transit and Highways) Program, who in turn
issued a subcontract to the University of Illinois- Chicago ( UIC) for some of the work that
needed to be based on collection of local operational data. Separate local stakeholder advisory
committees were formed for the two projects to provide reality checks on the viability of the
ideas to be proposed and to engage the key stakeholders in discussions that could lead to more
detailed planning for system implementation if the results of the initial feasibility studies appear
promising.
2
The case studies are primarily intended as evaluations of the real- world implementation issues
associated with use of CVHAS technologies, to help identify the highest- priority problems that
will need to be studied in further research on CVHAS. The key case study issues involve:
• Comparison of CVHAS solutions with conventional- technology solutions to identify
differences in the most important measures of effectiveness;
• Identification of the incremental benefits that can be provided by each CVHAS
technology in representative applications;
• Identification of the incremental costs associated with implementation of CVHAS
technologies in these applications;
• Identification of practical constraints to the deployment of CVHAS technologies;
• Identification of potential synergies when several CVHAS technologies are combined;
• Assessment of timelines for CVHAS implementation, considering both technical and
non- technical issues.
These issues are all of national significance, and should be relevant to all of the CVHAS states,
regardless of the specific application site( s) chosen for the case studies. In addition, if the case
study results appear promising for these specific sites, they should provide the foundation for the
development of more detailed planning efforts to point toward development of specific
deployment projects, which could then proceed under local sponsorship.
3
2.0 COOPERATIVE VEHICLE- HIGHWAY AUTOMATION SYSTEMS ( CVHAS)
2.1 CVHAS Attributes
Before the planning evaluations can be done, it is first necessary to specify the types of
technology that are under consideration. The CVHAS technologies have been under
development for many years, and the first commercial products that use these technologies have
only been on the market for a relatively short time. However, many more CVHAS products
should become available within the next two decades, providing a rich basis for system design
and evaluation. Most of the technologies are very similar for the applications to transit buses
and commercial trucks, but there are likely to be significant differences in their respective costs
and benefits because of the differences between the two application environments.
Figure 2.1 shows a schematic view of the range of possible CVHAS technologies, considering
the two key dimensions of the degrees of automation and of cooperation.
FIGURE 2.1 CVHAS Technology Characteristics
The terms used in Figure 2.1 are defined as follows:
4
• Warning – Audible, visible or haptic cue to alert driver to a potentially unsafe
condition
• Control Assistance – Automatic control of a portion of the driving function to assist
the driver by relieving workload ( e. g., adaptive cruise control) or to enhance safety
( e. g., collision avoidance braking)
• Full Automation – Completely automatic control of driving, relieving the driver of
responsibility for driving functions
• Autonomous Vehicles – Vehicles that derive all their information about the
environment from their own on- board sensors, without communication to or from the
infrastructure or other vehicles. By analogy to human drivers, the autonomous
vehicles can “ see”, but they cannot “ talk” or “ listen” to others.
• Cooperative Warning Systems – Warning systems that can receive information about
the vehicle’s driving environment by communication from other vehicles or from the
infrastructure, as well as from their own on- board sensors.
• Cooperative Vehicle- Highway Automation Systems ( CVHAS) – Systems that
provide driving control assistance or fully automated driving, based on information
about the vehicle’s driving environment that can be received by communication from
other vehicles or from the infrastructure, as well as from their own on- board sensors.
• Automated Highway Systems ( AHS) – Systems that provide fully automated driving
( which is only possible on separated, protected lanes), based on information about the
vehicle’s driving environment that can be received by communication from other
vehicles or from the infrastructure, as well as from their own on- board sensors.
On the vertical axis of Figure 2.1, we can see a range of degree of automation from warning
alone ( with the driver retaining the responsibility for taking all vehicle control actions), through
control assistance, and continuing to fully automated driving. The control assistance could be in
the form of adaptive cruise control, which helps the driver maintain a proper separation to the
vehicle ahead of his or her own, or assistance in steering to promote more accurate lane keeping.
Full automation means that the driver is no longer responsible for controlling the movements of
the vehicle, but it is controlled using electronic sensors and actuators, commanded by an onboard
computer.
A variety of warning systems have recently become available on the market, but the pioneering
system in the U. S. was actually the Eaton- Vorad forward collision warning radar system, which
has been available for commercial trucks and intercity buses since 1993. In the control
assistance category, the primary system is adaptive cruise control, which has recently become
available for use on heavy trucks and a few high- end luxury passenger cars in the U. S. The fully
automated vehicle systems have been used for many years as automated people movers at
airports and commercial business parks, and they have been used as urban transit systems in a
variety of other countries for several years.
On the horizontal axis of Figure 2.1, we can see the degree of cooperation ranging from none
( meaning autonomous vehicles, with no cooperation) to a variety of levels that could include
vehicle- vehicle cooperation, vehicle- roadway cooperation and fully integrated cooperation
among vehicle and roadway elements. The existing commercially available products and most
5
of the systems under design and evaluation in the USDOT’s “ Intelligent Vehicle Initiative”
program are at the low end of the cooperation scale, but interest is growing rapidly in the
improvements that could be gained with increasing cooperation enabled by wireless
communications among vehicles and infrastructure devices.
2.1.1 CVHAS Opportunities in these Case Study Projects
The case study projects described in this report are important to the development of CVHAS
technologies and identification of opportunities to deploy them for several reasons:
1. It appears most likely that earliest deployments of CVHAS technologies will be on heavy
vehicles operating on their own special rights of way for a variety of reasons:
1.1 Easier to develop and acquire rights of way for public purposes ( transit service,
getting trucks off mixed- traffic roads)
1.2 Maturing technologies can be used more safely by professional drivers on
professionally maintained vehicles than by the general public on vehicles that may
not be maintained at all
1.3 Costs of the technologies are a smaller percentage of total vehicle costs and vehicles
are used much more intensively than private automobiles, so these costs are
amortized much faster
1.4 Benefits in travel- time reduction, trip reliability and safety can be translated more
directly into cost savings than for private cars
1.5 Customized, small- lot production of vehicles makes it possible to introduce the
CVHAS technologies into the production process faster than for automotive mass
production
1.6 Packaging of new technological elements is easier on larger vehicles
1.7 Heavy vehicles already have more onboard electronic infrastructure to use as a
foundation for more advanced capabilities than passenger cars
2. Case studies of applications of CVHAS in specific sites are needed in order to shed light
on important issues such as the definition of system operating concepts, system designs,
institutional opportunities and constraints and system benefits and costs to the various
stakeholders, as well as to society as a whole.
3. Case studies focused on the solution of actual transportation problems can provide a basis
for focusing technical decisions and refining system design trade- offs.
4. The results of the case studies can be used to show the more general benefits of CVHAS
as part of the outreach messages.
5. Case studies of applications of CVHAS in specific sites are needed in order to shed light
on important issues such as the definition of system operating concepts, system designs,
institutional opportunities and constraints and system benefits and costs to the various
stakeholders, as well as to society as a whole.
6
6. Case studies focused on the solution of actual transportation problems can provide a basis
for focusing technical decisions and refining system design trade- offs.
7. The results of the case studies can be used to show the more general benefits of CVHAS
as part of the outreach messages.
8. Case studies for diverse locations around the country ( and particularly locations outside
California) can provide direct evidence of the broad, national applicability of CVHAS, to
help stimulate broader interest in CVHAS, including at USDOT.
2.1.2 CVHAS Benefit Opportunities
CVHAS technologies can provide a variety of benefits to transportation system operations.
These can be summarized as:
( a) Enhanced line- haul capacity/ reduced congestion – Automatic longitudinal control ( vehicle
following) makes it possible for vehicles to drive more closely together than they could under
normal driver control. This means that a single lane of vehicles under automatic longitudinal
control can accommodate more vehicles per hour than under manual control. That increased
capacity means that congestion delays can be reduced for the equipped vehicles, or alternatively
it should be possible to provide the capacity needed to avoid congestion with fewer lanes than
would otherwise be needed, saving on construction and right- of- way costs.
( b) Reduced lane width – Automatic lateral ( steering) control makes it possible for vehicles to
follow their lanes more accurately than drivers can normally steer, which makes it possible for
the lanes to be only slightly wider than the vehicles. This introduces the potential for saving a
portion of the cost of constructing these lanes, especially where they need to be accommodated
on elevated structures or underground. The narrow lanes also reduce the cost of right- of- way
acquisition and in special cases can produce major cost savings by enabling the lane to fit in a
place that might otherwise be impossible, or enabling the lane to be provided at grade level
rather than on much more costly elevated structures.
( c) Improved safety – A variety of the CVHAS technologies, but especially the warning
systems, should improve safety by reducing the probability of occurrence of crashes. These can
apply to a variety of crash types, ranging from lane departures to rear- end crashes and crossing-path
crashes at intersections.
( d) Improved operational efficiency – Several of the CVHAS technologies can improve
operating efficiency in different ways. Automatic steering control for precision docking of buses
at bus stops can reduce the time needed for passenger boarding and alighting, especially when
there are significant numbers of elderly, wheelchair- bound, or load- carrying passengers.
Automated operation of buses in maintenance facilities can save maintenance labor costs.
Automated operation of trucks on special truck ways could eventually save driver labor
expenses.
7
( e) Reduced fuel consumption and pollutant emissions – Vehicles cruising at constant speed
consume less fuel and produce less pollution than vehicles that are accelerating and decelerating
frequently. The congestion- reducing ability of automatic longitudinal control systems should
significantly reduce the occurrences of stop- and- go congestion for the equipped vehicles.
Furthermore, the automatic control of acceleration and braking can be programmed to do these
maneuvers smoothly and gradually, so that they are cleaner and more energy efficient than if
they were done more abruptly. Finally, close- formation platoon driving of vehicles can
significantly reduce aerodynamic drag at highway speeds, leading to savings in fuel consumption
and emissions.
( f) Reduced driving stress and fatigue – Relieving the driver of some or all of the tasks of
driving can reduce the stress and fatigue associated with driving, especially for professional
drivers who need to drive all day. Control assistance systems can provide partial relief, while
fully automated systems can change the driver’s role more significantly, turning it into more of a
supervisory or customer service assignment than manual labor. This category of benefits is
harder to measure than the others, and cannot be relied upon until there is a considerable body of
experience with drivers using these systems on a daily basis.
2.1.3 Incremental Cost Generators
The benefits of CVHAS systems are of course not gained for free, because there are costs
associated with implementation of these new systems. There are up- front engineering and
development costs, as with all new technologies, but these should be amortized across the
deployed systems. The costs of these systems are primarily capital costs of acquisition, but it is
important that they be compared equitably with the costs of the alternatives.
While partially automated and non- automated driving could be used on the same roadway, the
more advanced CVHAS technologies ─ involving fully automated driving ─ require use of
roadways that are fully segregated from non- automated vehicle operations. The costs of these
roadways are very site- dependent, but in the highest density urban areas they are likely to be
substantial. The key evaluation issue involves comparing the costs of the roadways intended for
automated vehicles with the costs of the roadways that will otherwise be needed for non-automated
vehicles. Since the additional costs for CVHAS technologies in the infrastructure
tend to be small ( communications transceivers and special reference markings), and the size of
the infrastructure could be somewhat smaller than the analogous conventional infrastructure, the
incremental costs could be either positive or negative.
The CVHAS costs that are generally most significant are associated with the additional
equipment required on vehicles. This depends on the level of capability to be provided, the
expected production volume of the equipment, and the year of implementation ( which
determines how much of the equipment may already be standard on vehicles for other reasons).
Maintenance and operation costs for the CVHAS technologies are difficult to anticipate in
advance of actual experience with products deployed in the field, but they should generally be
small compared to the acquisition costs if the systems have been well designed.
8
2.2 Applicability of CVHAS Technologies Based on Right- of- Way Restrictions
For a limited- scope application case study it is necessary to narrow consideration to a limited set
of the most promising system concepts rather than trying to consider the full range of
possibilities. The concepts that are most applicable for the Chicago bus and truck applications
turn out to be very similar to each other, and their costs are therefore also similar, simplifying the
study somewhat. The applicability of CVHAS concepts is closely coupled to the degree of
mixing that is permitted between the CVHAS- equipped vehicles and the general unequipped
vehicle traffic. CVHAS concepts at the lower levels of automation functionality ( warnings and
the most basic control assistance) can be applied essentially anywhere, because the vehicle
driver will be expected to maintain vigilance to deal with emergency conditions. As the level of
automation increases, however, it is less likely that the driver will be able to maintain full
vigilance to deal with all of the hazards created by the worst- behaving drivers, cyclists and
pedestrians in the public roadway environment.
The state of the art in sensing and signal processing technology does not enable the CVHAS
systems to take over full responsibility for vehicle safety in the complicated unrestricted
roadway environment, nor is it likely to enable that for many decades to come. Indeed, at the
fully automated level of driving functionality it will be essential to provide physical segregation
of the equipped vehicles from the unequipped for the foreseeable future.
Table 2.1 provides a summary description of the technologies that could be applied to transit
buses as a function of the degree of right- of- way restriction that is imposed. Mixed traffic flow
refers to unrestricted use on public roads that are shared with other motor vehicles, as well as
pedestrians and bicyclists. This is the most challenging operating environment because of the
complexity and unpredictability of its conditions. In this environment, the driver must remain
fully in charge of the driving process and must continuously monitor the vehicle surroundings
for hazards.
The partially segregated environment is one in which the CVHAS equipped vehicles would
normally coexist primarily with other similarly equipped vehicles, but their right of way could be
shared occasionally and temporarily by other vehicles. In this case, it should be possible to take
advantage of the opportunities provided by automatic steering control, but the more advanced
control functions could not be implemented because of the hazards introduced by the “ other”
vehicles. In the fully segregated and protected environment, all vehicles with access to the
roadway would be suitably equipped with sensors and communication devices and could safely
coordinate their operations. Any faults that occur would be detected and reported so that all
vehicles could respond appropriately and safely. This is the environment in which the maximum
benefits can be gained from use of the CVHAS technologies, but it is also the environment that
requires the largest political commitment to achieve because of the need to exclude all non-equipped
vehicles from access.
Technologies that could actually be used on the buses in Chicago include collision warning,
transit signal priority, precision docking, automatic steering control, automatic speed and
spacing control, and fully automated vehicle operation.
9
Collision warning systems could augment the driver’s normal driving and could provide alerts to
hazards of which he may be unaware, and could also help out in conditions in which the driver is
distracted or less than fully alert ( fatigued or health impaired). Such systems may take the form
of forward, rear, and side hazard warnings and can be delivered to the driver by either auditory,
haptic, or visual cues. The driver retains responsibility for corrective actions based on the
warnings provided. Technologies that may be used in these systems include radar, ultrasound or
laser sensors and threat assessment software and the driver interface.
Transit signal priority is an operational strategy that facilitates the movement of transit vehicles
through traffic- signal controlled intersections. By reducing the time that transit vehicles spend
delayed at intersection queues, transit signal priority can reduce transit delay and travel time and
improve transit service reliability, thereby increasing transit quality of service. It also has the
potential for reducing overall delay at the intersection on a per- person basis because giving
priority to a bus and thereby saving all of its passengers an amount of time at least the length of
the red cycle is going to produce more overall benefits than the costs associated with a few
seconds of delay to the car drivers waiting slightly longer for their green signal on the cross
street. At the same time, transit signal priority attempts to provide these benefits with a
minimum of impact on other facility users, including cross- traffic and pedestrians. The
preferences given to buses may, for example, be in the form of an early green ( red truncation) or
green extension. Technologies include vehicle detection, identification, and location systems to
identify a bus and communicate to a roadside signal controller cabinet together with GPS,
differential GPS, dead- reckoning for positioning and wireless communication.
Precision docking is a low- speed automated positioning of buses relative to the curb or
loading/ unloading platform at bus stops under direct bus driver supervision. It offers precisely
controlled lateral positioning with tolerances of 1 to 2 cm and it becomes possible to load and
unload passengers as easily as rail transit vehicles, reducing the dwell times at bus stops and
improving accessibility for mobility- impaired passengers ( especially those bound to
wheelchairs). It is difficult and stressful for bus drivers to try to achieve this kind of position
accuracy, and if they try they often scuff their tires against the curb, creating maintenance and
wear problems, as well as discomfort for their passengers. Since the precision docking maneuver
is performed at low speed1 in well- defined locations, and under direct supervision of the bus
driver, it is a form of vehicle automation that could be implemented relatively early and with a
minimum of liability concerns. Moreover, the driver would be able to devote more attention to
looking out for possible safety problems involving pedestrians. Technologies that may be used in
these systems for sensing include roadway “ magnetic marker” sensors, vision or optical systems
together with an electronically controlled steering actuator.
Automatic steering control is essentially the same as precision docking in that it automatically
steers the bus to stay centered in a lane but it is not limited to low speeds that are necessary for
docking a bus at a stop. Automatic speed and spacing control, rather than the driver, commands
the bus speed and allows for buses to be operated very close together. Technologies for these
systems include forward ranging sensors ( radar or laser), electronic control of the engine and the
1 In principle, there is no speed difference between automated or manual control
10
brakes, and vehicle- to- vehicle data communication. More detailed information on these
technologies may be found in Appendix I.
TABLE 2.1 Applicability of CVHAS Concepts by ROW Restriction
Right- of-
Way
Restriction
s
Collision
Warning
Traffic
Signal
Priority
Precision
Docking
Automatic
Steering
Control
Automatic
Speed and
Spacing
Control
Fully
Automated
Vehicle
Operation
Mixed
traffic flow X X X
Partially
segregated
bus lane
X X X X
Fully
segregated
bus lane
X X X X
11
3.0 BUS TRANSIT SYSTEMS IN THE LOOP AREA OF CHICAGO
3.1 Background Information
The city of Chicago has always been a major hub for mass transit, and it currently hosts the
second largest public transportation system in the nation. Buses represent a major component of
that system, with one million rides being taken daily on fleet of 2,080 buses ( 3- 1). Within the
city limits, the bus system is particularly crucial, transporting people to and from their jobs on a
daily basis. Unfortunately, however, public opinion of riding the buses and trains in Chicago is
alarmingly low – with only 34% of riders having a positive perception of it according to a recent
poll ( 3- 2). The obvious result has been more people choosing personal transportation instead,
decreasing ridership and increasing traffic. Though that may sound bad, things are actually
headed in the right direction due to improvements in service and facilities, as overall ridership has
increased in 2001 for the fourth consecutive year ( 3- 3). The key to having this trend continue is
to persist in improving the service, and automation represents a very promising way of doing so.
Automation expands upon the concepts of Bus Rapid Transit ( BRT) by applying advanced
technologies as a way to enable fully or partially automated vehicle control. Exactly how and to
what extent these CVHAS technologies are used depends on the properties of the particular area
being serviced. However, the potential benefits of automation are very compelling. Such
benefits include:
• Decreased travel times
• Increased schedule adherence
• Increased accessibility
• Increased safety
• A smoother ride
• Operation on narrower right- of- ways
• Increased vehicle and passenger capacity per lane
• Environmental benefits ( reduced emissions)
Over the course of the last sixteen years there have been numerous investigations into improving
transit service in the Loop. In this report we focus on three of these studies as they have been the
prime motivation for the current investigation. The oldest study is the Central Area Circulator
Project ( CACP) in 1987 ( 3- 4, 3- 5, and 3- 6) with the others being two recently completed studies,
namely, the Chicago Central Area Plan ( 3- 7) and the Carroll Avenue Busway Plan ( 3- 8).
3.1.1 Central Area Circulator Project
In 1987 Chicago’s Regional Transit Authority ( RTA) began a study to assess the need for new
downtown transit in Chicago resulting in the Central Area Circulator Project ( CACP). CACP
was a 9 mile, 32 station, light rail transit system designed to transport an average of 100,000
riders daily to major Central Area destinations such as the Illinois Center, Navy Pier, North
Michigan Avenue, State Street, the Loop, Central Station and McCormick Place. The project
budget was estimated to be $ 775 million with funding from the Federal Transit Administration,
12
the state of Illinois, and the Circulator Special Service Area Taxing District. The CACP was
proposed to interconnect all existing transit systems and link them to the activity centers in
downtown Chicago. This interconnecting system would make it easier for travelers to use transit
in Chicago thereby reducing congestion. RTA and the Chicago Development Council, a private
sector consortium of developers and downtown property owners, funded the study.
The CACP evaluated a number of modes to provide transportation downtown including bus,
automated guideway transit, and subways but eventually light- rail transit was selected as the best
alternative. The study found that light rail transit offered the best combination of speed and
capacity with only moderate capital and operating costs. The light rail system may have changed
downtown by creating corridors giving pedestrians and the light rail system priority over
personal vehicles.
Improving the bus system and exclusive busway lanes in the high- traffic corridors were
evaluated in detail because the initial cost would be approximately one- third that of the light rail
system. The critical disadvantages of the bus option were capacity and speed. Although large
three- sectioned articulated buses were available at the time they were not yet legal to operate in
the U. S. Therefore, standard buses would have to be used. However, these would not have
offered as much capacity as the light rail system being proposed. A full- scale bus system would
have peak hour capacity of 10,000 passengers per hour but would require very close spacing
between buses and operation at the upper limits of efficiency. On some streets the new system
would add 160 vehicles per hour creating noise, pollution and congestion in pedestrian areas and
unacceptable delays on cross streets. In the future, expanding the capacity of the system would
be almost impossible since the system would already be basically saturated with buses. MPC
found it “ impossible to structure a new bus system that could move people much faster than the
current service, even with exclusive busways, because the sheer volume of vehicles overwhelms
any attempt to coordinate traffic signals in favor of bus movements” ( 3).
The proposed light rail system ( Figure 3.1) would operate on a dedicated right- of- way with
signal priority at intersections. The vehicles would run in trains with up to three cars with a
capacity of 550 people, equivalent to approximately eight buses. Peak hour capacity in the peak
direction would be 12,000 passengers per hour ( 20 trains/ hour at 200 people/ car). The light rail
transit system would co- exist with pedestrians and personal vehicles as well as make connections
with CTA rail transit and Metra commuter rail lines for easy travel within the Central Area and
outlying neighborhoods and the suburbs.
Initially light rail transit was selected over bus alternatives for the CACP because it offered
speed and capacity advantages over buses for moderate capital costs. However, over the course
of the system’s planning the cost of the proposed light rail system grew until it became
prohibitively expensive to fully engineer and build. By 1990 the CACP was dropped from the
regional transportation plan but it continued to be investigated into the mid- 1990s. In 1994 some
favored only a limited version of the plan connecting Navy Pier, Grant Park, the Museum
Campus, Soldier Field, and McCormick Place ( 4).
Initially light rail transit was selected over bus alternatives for the CACP. The former offered
speed and capacity advantages over buses for moderate capital costs, however, such costs grew
13
over the course of the system’s planning time horizon until it became prohibitively expensive to
fully engineer and build. Modern CVHAS technologies offer the opportunity for buses to
provide the same advantages as light rail transit, but at a significantly more affordable price:
14
FIGURE 3.1 The Route of the Proposed Light Rail System for the Central Area Circulator
Project.
15
( 1) Speed  CVHAS technologies can make it possible for buses to operate at the same speed as
light rail cars:
• Precision docking at bus stops can reduce dwell times, as well as provide better quality of
service to passengers ( especially mobility impaired), and reduce driver stress and
maintenance problems from tire wear.
• Automatic steering control makes it possible to maintain full speed and good ride quality
while traveling in very narrow rights- of- way, as well as permitting reduced lane width and
therefore reduced capital cost.
• Traffic signal priority technology, using wireless communications between buses and the
traffic signal system, can enable buses on the mainline circulator route to obtain priority over
cross traffic, reducing or potentially eliminating signal delays for the passengers.
( 2) Capacity  CVHAS technologies also make it possible for buses to provide equivalent
capacity per lane to light rail cars:
• Use of electronically- coupled bus platoons in a fully protected right- of- way environment can
enhance capacity and offer a high level of service to accommodate sufficiently large travel
demand. The electronic coupling technology means that several buses ( even buses from
diverse origins) can be coupled together to form a “ virtual train” and these “ virtual trains” of
buses can be operated closer together than traditional light rail trains.
• Modern double- articulated buses of the type used in a variety of BRT systems around the
world also provide significantly higher passenger capacity per bus than the traditional single-unit
buses that were available in the U. S. at the time of the original CACP study.
3.1.2 Carroll Avenue Busway Study
The information obtained regarding the Carroll Avenue busway came from the studies prepared
for the Chicago Department of Transportation by the Parsons Company. During the design of the
new route, an east- west corridor was deemed to be the best selection because of the ongoing
challenges with efficiently transporting people from the west side of the Loop ( major terminus
for Metra Commuter Rail lines arriving from the western suburbs. Moreover, the possibility of
using a dedicated transit facility was also part of the favored option. This option may be
achieved using Carroll Avenue under the Merchandise Mart. Increasing congestion in the area
north of the Chicago River has generated interest in using the “ Pacific Railroad” which lies
between the north shore of the river and Kinzie Street and is no longer in use, as a dedicated
transit facility. This corridor can connect from the Chicago River at Canal Street to the west side
of Rush Street and using this option under an appropriate operational strategy would improve
travel time by 60% and enhance bus connection between the Central District Metra and CTA rail
stations. Figure 3.2 depicts an overhead view of the Carroll Avenue route relative to major
activity centers in this part of the city.
16
FIGURE 3.2 Carroll Avenue Busway ( Reference 3- 8)
Carroll Avenue is a 7.2 – 8.4 m. wide road that is currently used for parking and
loading/ unloading purposes. The traffic in the corridor is a mix of automobiles and singles- unit
trucks. There are a total of six ramps entering the corridor, and during peak morning hours most
of the traffic enters at LaSalle Street between Clark and Dearborn. There are two main access
points on the west side of the avenue, namely, a ramp at Orleans, by crossing the river at the
existing Kinzie Street Bridge and a new bridge over the river in the same location of the old
railroad. The project team visited the case study locations and photographs taken of the Carroll
Avenue area are included in Appendix II.
3.1.3 Chicago Central Area Plan
The following is an excerpt from the Chicago Central Area Plan of 2003 ( 3- 7):
CTA buses currently use eastbound lanes on Washington and Adams and
westbound lanes on Madison and Jackson. These lanes are affected by vehicles
making right turns at cross streets and by vehicles exiting driveways, extending
travel times for bus riders and discouraging transit use. As a first step, these on-street
bus lanes will be upgraded through improved signal timing, streetscape
enhancements and other amenities. An exclusive transitway may be created at the
street level, in the short term, on Adams and Monroe Streets.
If warranted by future traffic growth, a below- grade transitway could be built on
Monroe Street to improve east- west bus times through the Loop. This below-grade
transitway would make use of a right- of- way reserved by the City for a
potential east- west subway in the 1970’ s. It would extend from Michigan Avenue
17
to Clinton Street, crossing the Chicago River via tunnel. Portals would permit
buses to enter and exit at Michigan Avenue and at Clinton. A connection could
also be provided to the existing South Lakefront transitway to McCormick Place.
Buses operating in the East- West transitway could be primarily existing line- haul
routes that currently use Loop streets. Convenient connections could be provided
to the State and Dearborn subways below. Escalators and elevators would
transport riders between platform and street level, with bus waiting times
displayed on electronic signs. The platforms could be extended to create a
continuous pedway between Michigan Avenue and Union Station, with
connections to the existing pedway. As a first step, this right- of- way may also be
developed as a pedway.
Figures 3.3 and 3.4 are also taken directly from the Chicago Central Area Plan and show
an artist’s rendering of a future East- West busway in the Loop.
FIGURE 3.3 A Future East- West Busway on Adams Street ( Reference 3- 7)
FIGURE 3.4 A Future East- West Busway under Monroe Street ( Reference 3- 7)
18
In summary, Chicago is considering two plans to connect the east and west sides of the Loop: a
short- term plan ( before 2011) placing bus lanes on Adams and Monroe Streets ( referred to as the
East- West Bus Lanes), and a long- term plan ( 2012- 2016) that would connect the West Loop
Transportation Center to McCormick Place via a busway under Monroe Street ( referred to as the
Monroe Busway) and the currently existing Lakefront Busway.
Currently, there already exists a bus lane on Adams Street. However, the lane is not truly
exclusive because of the presence of illegally parked cars, right turning vehicles and vehicles
exiting/ entering driveways. These problems could potentially be solved by adding a physical
barrier of some type ( Figure 3.3), eliminating all conflicting driveways and using traffic signal
priority to deal with right turning vehicles. The barrier would also permit automatic steering
control, and thus reduce the required lane width. The same may also said for Monroe Street,
which currently is not used by the CTA bus fleet.
The initial plans for the Monroe Busway have already been completed by TranSystems
Corporation under contract to the Chicago Department of Transportation ( CDOT). The plan
envisions a three- lane busway with eight docking stations, transporting people between
Michigan Avenue and Clinton Street. The basic layout and docking stations are pictured in
Figures 3.5 and 3.6.
FIGURE 3.5 Top View of Proposed Monroe Busway ( Source: TranSystems, Inc. and
Chicago Department of Transportation)
19
As can be seen from Figure 3.5, the center lane runs in both directions. It would allow docked
buses at a particular bus stop to be passed by other buses that have already docked and picked up
passengers, or buses that do not provide service to that stop. It would also make it possible for
emergency vehicles to use the busway when absolutely necessary.
FIGURE 3.6 Monroe Busway Docking Stations ( Source: TranSystems, Inc. and Chicago
Department of Transportation)
Each platform, as well as each lane, would be 12 feet wide. Grating above each lane will
function to provide natural lighting and give the busway a more “ open” feeling. Kiosks at the
street level will lead into the escalators and elevators to transport people to and from the busway.
These features are illustrated in Figure 3.7.
20
FIGURE 3.7 Front View of Proposed Monroe Busway ( Source: TranSystems, Inc. and
Chicago Department of Transportation)
Going from west to east, the busway starts out at the West Loop Transportation Center, where it
connects to the proposed underground Clinton Busway and also has a set of portals. It then goes
underneath the Chicago River and then returns to just below street level, extending over the
existing Dearborn and State Street Low Level Subways. Some buses would dock at each of the
stations, while others will likely pass through the entire busway without stopping. While portals
will exist at Michigan Avenue, there is also strong consideration to providing a direct connection
to the Lakefront Busway. The total length from Clinton St. to the Lakefront Busway is 0.97
miles.
3.2 Selection of Case Study Alignments
We met with the project stakeholder advisory committee – consisting of members from CTA,
CDOT and RTA in September 2002. During this meeting the project team presented information
about CVHAS technologies and concepts to the stakeholder advisory committee. The
stakeholder advisory committee proposed transit routes that could potentially benefit from
CVHAS technologies both in the near term ( in the next five to ten years) and in the long term.
We examined the near and long term transportation environment for transit vehicles on these
routes.
Figure 3.8 shows transit routes in the Chicago downtown area that could benefit from CVHAS
technologies in the near term grouped by their right- of- way characteristics. In Figure 3.8 the red
color denotes mixed traffic operations ( CVHAS buses freely mixed with normal traffic), while
blue denotes partially segregated transportation environment for transit vehicles.
21
Figure 3.9 shows transit routes in the Chicago downtown area that could benefit from CVHAS
technologies on the long run grouped by their right- of- way characteristics. In Figure 3.9 again
red denotes mixed traffic, blue denotes partially segregated and yellow denotes fully segregated
transportation environment for transit vehicles. The original map from which Figures 3.8 and
3.9 were modified to show the location of the case study corridor; the CVHAS right- of- way
characteristics are from the Chicago Central Area Plan ( CCAP) in Reference 3- 7, in which the
original figure in that document is Figure 3.2.8.
FIGURE 3.8 Routes in Downtown Chicago Potentially Benefiting from CVHAS
Technologies in the Near- Term ( Reference 3- 7)
22
FIGURE 3.9 Routes in Downtown Chicago Potentially Benefiting from CVHAS
Technologies in the Long- Term ( Reference 3- 7)
During our meeting the stakeholder advisory committee recommended the following three case
studies for primary attention shown in Figure 3.10:
• East- West At- Grade bus- only lanes on arterial streets – Near- term alternative
• East- West Underground “ Monroe” Busway – Long- term alternative
• Clinton- Carroll Avenues Busway – Long- term alternative
3.3 Method Applied in Case Studies
For each of the three case studies, that is, the near- term East- West Loop arterial scenario, the
long- term underground Monroe busway, and the long- term Clinton- Carroll Avenue busway, we
perform incremental benefit cost analysis of CVHAS technologies on the case study transit
corridors. In such incremental analysis we isolated and measured the benefits and costs due to
applying CVHAS technologies.
First, we describe the case study corridor in its current state through current data and map. We
give information about the running way characteristics, such as number of lanes, lane width,
intersections, traffic signals; what type of traffic environment the future bus operation will take
place in term of segregation from general traffic; stop locations and characteristics; transit routes
currently using the corridor; current transit operation characteristics, such as travel time,
operating hours; and passenger demand, where available. This will establish the location, the
physical and transit operational characteristics of the corridor studied.
23
FIGURE 3.10 Three Bus Transit Case Study Corridors ( Reference 3- 7)
Second, we discuss, for each of the three scenarios, the particular areas where CVHAS
technologies may be used and benefits gained. For example, in the near- term east- west scenario,
we discuss collision warning systems, precision docking, and traffic signal priority as the
CVHAS technologies most appropriate for application here.
Third, we discuss the data inputs that are required, appropriate performance measures to use to
measure the effects of CVHAS technologies, and anticipated benefits of CVHAS technologies.
Next, we discuss our evaluation and present our findings for each of the specific areas for each
of the three scenarios, which includes a determination of benefit- cost ratios, a “ break- even”
analysis and a sensitivity analysis of initial findings.
3.4 East- West At- Grade  Near- Term Case Study
3.4.1 Case Study Corridor
The following sections will describe the case study locations.
Currently, the two one- way pairs of East- West arterial streets that are major transit corridors are:
1. Washington Ave. – East bound with Madison Ave. – West bound;
2. Adams Ave. – East bound with Jackson Ave. – West bound
24
They are marked as four parallel red lines on the map of downtown Chicago in Figure 3.10. The
corridors are marked between Canal Street and Michigan Ave. There are 10 major North- South
bound streets crossing the East- West arterials between and including Canal and Michigan.
Currently, Madison Ave. has four lanes: the right most is a bus- only and right turn only lane.
Right turn is allowed at every other cross street. The lane’s width is mostly 13’ with the
exception between Wells Street and Wacker Drive, where it is only 10’. The two middle lanes
are straight through lanes while the left- most lane is left only at every intersection.
Washington Ave. has similar configuration. Here the bus lane is mostly 10’ wide, with the
exception between Wacker Drive and Franklin Street where it is 15’. Before any intersection
where a left turn is allowed a fifth lane is squeezed in.
Both Adams and Jackson Ave. have three lanes with the right- most lane a bus- only and right
turn only lane. On Adams the bus- only lane is mostly 10’ wide, while on Jackson it is mostly
12’. 2
Cars use bus lanes for right turns. No parking is allowed in the bus- lanes at any time. This is
enforced by police and towing. Trucks are prohibited to stop in the bus lane in peak time but
they can use the bus lane to turn into loading docks.
Bus stops are on- line, mostly located on the near side of the intersections.
Through the Loop area the traffic signals are directed by a computer system. However, there is
no central control. All control needs to be manually reprogrammed at each intersection. Signals
operate on a simultaneous 75 second cycle that starts on zero second offset North- South bound.
Pedestrian and arrow turn signals vary by intersection. For pedestrians, “ Don’t walk” is
displayed during arrow turning signal phase. Based on information from CDOT, there is no data
on pedestrians blocking right turning traffic. CTA does not have data on how much time buses
spend stopped at red lights. Currently, there is no signal priority anywhere in Chicago.
Buses serving the Loop area are stationed at two bus depots. The fleet is made up of
conventional and low floor buses, and both are used on the currently examined routes.
1. Bus Depot # 1: Total # of buses: 234, low floor: 117
2. Bus Depot # 2: Total # of buses: 221, low floor: 122
Buses are not equipped with any kind of AVL technologies.
Peak periods in the Loop Area are:
2 Washington Avenue from Austin to Michigan, Pavement markings, Last revised at 2- 08- 01
Madison Avenue from Austin to Michigan, Last revised at 2- 08- 01
Jackson Avenue from Jefferson – Michigan, Concurrent bus lanes, Last revised at 2- 16- 01
Jackson from Austin to Lake Shore, Last revised at 5- 1- 92
Adams Avenue from Jefferson – Michigan, Concurrent bus lanes, Last revised at 2- 9- 01
All drawings Prepared by the City of Chicago, Department of Public Works, Bureau of Traffic Engineering and
Operations ( Reference 3- 9)
25
AM: 7: 00- 9: 30AM all direction
PM: 3: 30- 7: 00PM all direction
Transit operation is schedule based. Buses can enter regular traffic ( leaving the bus lane) to over
take slower moving buses, or illegally parked vehicles. Passengers board only at the front door,
but alight anywhere. Fare collection is either by coins or cards ( either feed- into- reader or
proximity card).
Table 3.1 shows the routes currently using the Washington- Madison arterials:
TABLE 3.1 CTA Bus Routes on Washington- Madison Streets
Washington E – Madison W
Bus number Headway Travel time Comment
14 E 12 min in AM
4- 7 min in PM
W/ Jefferson –
Balbo/ Michigan
12 min
Express
PM
14 W
3 - 6 min in AM
12 min in PM
Madison/ Michigan
– W/ Jefferson
16- 18 min
Jeffery
express AM
20 E 7: 00- 8: 20 5min AM
8: 20- 9: 30 6- 8 min
AM
3: 30- 6: 00 5- 9 min
PM
6: 00- 7: 00 9 min PM
NA Owl service
20 W 7: 00- 8: 00 8min AM
8: 00- 9: 30 5min AM
4- 6 min in PM
NA
56 E 8- 10 min AM
8- 10 min PM
NA
56 W 10 min AM
8- 10 min PM
NA
157 E 7: 00- 9: 00 9 min AM
9: 00- 9: 30 12 min
AM
3: 30- 5: 00 10min PM
5: 00- 7: 00 15min PM
Canal/ Adams
( Union st) to
Randolph/ Mich
12 min
157 W 10 min AM
3: 30- 6: 00 10min PM
6: 00- 7: 00 15min PM
Mich/ Randolph to
Clinton/ Jackson
13min
Data in table is from Reference 3- 10.
Based on the published schedule, scheduled travel time on Washington between Jefferson and
Michigan is 14 minutes; on Madison between Michigan and Jefferson it is 16 minutes.
Because there are multiple routes on this section on Madison – Washington Avenue there is a
bus every 2 minutes for passengers traveling within the Loop Area. This data is verified from
CTA’s bus schedule as presented in Tables 3.2 and 3.3. There is a bus on average every 1.7 –
26
2.4 minutes on these two arterials between Canal and Michigan. However, those who wish to
travel further out away from the Loop Area must wait for their bus. Then the headway is based
on schedule and it is anywhere between 3 to 15 minutes, depending on the route.
TABLE 3.2 Frequency of Buses on Washington Avenue During Peak Periods
Washington Avenue AM PM
Headway Number of
buses per hour
Headway Number of
buses per hour
14 E 12 min 5 4 – 7 min 15 – 8.5
20 E 5 – 8 min 12 – 7 5 – 9 min 12 – 6.6
56 E 8 – 10 min 7.5 – 6 8 – 10 min 7.5 – 6
157 E 9 min 6.6 10 – 15 min 6 – 4
Total 1.9 – 2.4 min 31 – 24.5 1.5 – 2.4 min 40.5 – 25
TABLE 3.3 Frequency of Buses on Madison Avenue During Peak Periods
Madison Avenue AM PM
Headway Number of
buses per hour
Headway Number of
buses per hour
14 W 3 – 6 min 20 – 10 12 min 5
20 W 5 – 8 min 12 – 7 4 – 6 min 12 – 6.6
56 W 10 min 6 8 – 10 min 7.5 – 6
157 W 10 min 6 10 – 15 min 6 – 4
Total 1.4 – 2.1 min 44 - 29 2 – 2.8 min 30.5 – 21.5
The scheduled time to complete these cross- town runs is not directly accessible because no time
points on any of the routes listed in Table 3.4 corresponds to the section we are investigating.
Time points are located such that they indicate scheduled travel time for a longer section of the
route that includes the section between Canal and Michigan. However, it is not unreasonable to
expect similar scheduled times to those on the parallel cross- town routes on the
Madison/ Washington pair.
27
TABLE 3.4 CTA Bus Routes on Jackson- Adams Streets
Jackson E – Adams W
Bus
number
Headway Travel time
( schedule
based)
Comment
126 E 7: 00- 8: 30 5- 9 min AM
8: 30- 9: 30 10 min AM
3: 30- 6: 00 10 min PM
6: 00- 7: 00 12min PM
NA Main route
126 W 7: 00- 8: 30 5- 9 min AM
8: 30- 9: 30 10 min AM
3: 30- 5: 00 8 min PM
5: 00- 6: 00 10 min PM
6: 00- 7: 00 15 min PM
NA
151 E 7: 00- 8: 00 8 min AM
8: 00- 9: 30 12- 14 min AM
2- 8 min PM
NA
151 W Irregular schedule:
1- 10 min
average:
7: 00- 8: 30 4min AM
8: 30- 9: 30 5- 12 min AM
5- 12 min PM
NA 151 L starts
operating at
6: 41PM
1 E 12 min AM
12 min till 6: 40 PM
NA Indiana/ Hyde
Park
Rush hours only
1 W 12 min AM
12 min till 6: 30 PM
NA Rush hours only
60 E 7 min AM
3: 30- 6: 00 6- 12 min PM
6: 00- 7: 00 15min PM
NA
60 W 7: 00- 8: 00 8 min AM
8: 00- 9: 30 7- 10 min AM
3: 30- 6: 00 7- 10 min PM
6: 00- 7: 00 12 min PM
NA
7 E 15 min AM
3: 30- 6: 00 15 min PM
6: 00- 7: 00 20 min PM
Jackson/ Canal -
Congress pl
12 min
Harrison
7 W 15 min AM
3: 30- 5: 00 12 min PM
5: 00- 6: 00 15 min PM
6: 00- 7: 00 20 min PM
NA
Data in table is from Reference 3- 10.
Bus headway is on average between 1.35 – 2.3 minutes on Jackson, and 1.45 – 2.5 min on
Adams Avenue between Canal and Michigan. However, those who wish to travel further out
away from the Loop Area must wait for their bus. Then the headway is based on schedule and it
is anywhere between 2 to 20 minutes, depending on the route. Tables 3.5 and 3.6 show the
frequency of buses on Jackson Avenue during the peak periods.
28
TABLE 3.5 Frequency of Buses on Jackson Avenue During Peak Periods
Jackson Avenue AM PM
Headway Number of
buses per hour
Headway Number of
buses per hour
126 E 5 – 10 min 12 – 6 10 – 12 min 6 – 5
151 E 8 – 14 min 7.5 – 4 2 – 8 min 30 – 7.5
1 E 12 min 5 12 min 5
60 E 7 8.5 6 – 15 min 10 – 4
7 E 15 min 4 15 – 20 min 4 – 3
Total 1.6 – 2.2 min 37 – 27.5 1.1 – 2.4 min 55 – 24.5
TABLE 3.6 Frequency of Buses on Adams Avenue During Peak Periods
Adams Avenue AM PM
Headway Number of
buses per hour
Headway Number of
buses per hour
126 W 5 – 10 min 12 – 6 8 – 15 min 7.5 – 4
151 W 4 – 12 min 15 – 5 5 – 12 min 12 – 5
1 W 12 min 5 12 min 5
60 W 7 – 10 min 8.5 – 6 7 – 12 min 8.5 – 5
7 W 15 min 4 12 – 20 min 5 – 3
Total 1.3 – 2.3 min 44.5 – 26 1.6 – 2.7 min 38 – 22
For all routes on all four arterials, the examined section between Canal and Michigan is only a
small section of the total routes. We do not have data on the percentage of passenger demand
that uses buses only in the Loop area. Only these passengers can take any route on this section.
All other passengers have to wait for their own bus. CTA does not collect passenger data per
stop and estimates of average daily passenger demand per route are based on fare box
collections. Data are shown in Appendix II.
Currently, we have inconsistent run- time information for these arterials between Canal and
Michigan:
• From the published schedule:
East- bound: Washington/ Jefferson to Balbo/ Michigan: 12 minutes
West- bound: Madison/ Michigan to Washington/ Jefferson: 16- 18 minutes
• From the field data collection:
West bound between Wabash and Canal ( excluding dwell time at Canal) 7.21 min. or 433 sec or
if dwell time at Canal is included, 8 min or 480 sec.
29
East bound between Canal and Wabash ( excluding dwell time at Wabash) 7.58 min or 455 sec
( data does not exist to include dwell time at Wabash).
A possible explanation for the inconsistency is if the published schedules include some
additional slack time to allow for unanticipated delays that may not have been encountered
during the times that the field data was collected. More detailed data on the bus routes along
these four parallel arterials may be found in Appendix III.
3.4.2 Evaluation of Near- Term East- West Alternatives in the Loop
3.4.2.1 Collision Warning Systems
Collision warning systems could augment the driver’s normal driving and could provide alerts to
hazards of which he may be unaware, and could also help out in conditions in which the driver is
distracted or less than fully alert, e. g., due to fatigue. Such systems may take the form of
forward, rear, and side hazard warnings and can be delivered to the driver by either auditory,
haptic, or visual cues. The driver retains responsibility for corrective actions based on the
warnings provided. Technologies that may be used in these systems include radar, ultrasound or
laser sensors and threat assessment software and the driver interface.
Our objective in this analysis was two- fold, again focusing on the four east- west streets in the
Loop ( Madison, Jackson, Adams, Washington). First, we assessed the impact that equipping
CTA buses with collision warning systems would have on the number of crashes involving these
buses; that is, how many crashes might have been avoided had the bus been equipped with
CVHAS technologies. Second, we estimated the return on investment from deployment of
collision warning systems.
The first step in our investigation was to examine CTA incident data records for 2002, followed
by a more concentrated examination of those incidents occurring on the four east- west streets
( Madison, Washington, Adams, and Jackson). The last stage in our evaluation was to assess the
return on investment from having CTA equip those buses running on the four east- west Loop
arterials.
We began our assessment with an examination of CTA incident data for 2002, which is the most
recent year for which there are complete records. In total there were 407 records in the database,
of which 12 records were duplicates, and 5 records indicated the apparent incident was not a real
incident at all. Thus there were a total of 390 records remaining, of which 134 ( 34.4%) were
located on one of the four east- west streets. In the database were included fields such as incident
location, date, time- of- day, whether there was an injury, the type of incident as described by one
of more of the Supervisory Call Codes3, and remarks/ details written at the time of the incident.
We examined closely these remarks to discover what action the bus was taking at the time of the
incident and the point of contact on the bus of the crash.
3 The Supervisory Call Codes are the shorthand expressions that CTA personnel use to communicate information
from the site of the incident to CTA offices. For example, common codes appearing in the database include “ 10- 73”
and “ 10- 71”, which mean “ Collision of CTA vehicle and other vehicle” and “ Collision of CTA vehicle and fixed
object, respectively.
30
Upon examining the database, we grouped the incidents into several categories by type within
which the records were aggregated as shown in Table 3.7. We have highlighted in bold italics
those incidents that we believe might have been avoided with the implementation of collision
warning systems on the buses. This belief is based on the current state of knowledge in research,
development, testing, and evaluation of collision warning systems and these systems are likely to
become available within the next ten years.
For two types of incidents, # s 1 and 2, proximity warning systems could help in these situations,
but are only effective at very short range ( up to a couple of meters), which means that they can
only be used when the vehicle is moving very slowly ( squeezing into a parking space). These
incidents likely occurred with vehicles moving faster, not on straight trajectories, and with
considerably less well- defined target obstacles ( such as the mirrors of other buses or
trucks). Moreover, detecting these impending crashes is very difficult. For incident type # 10,
these door- opening impacts occur with so little lead time that it is unlikely that any system would
be able to detect the door opening and issue a readily- understandable warning in nearly enough
time to cause the person to stop opening the door before hitting the bus.
TABLE 3.7 Distribution of Incident Types in the Loop in 2002
INCIDENT TYPE NO INJURIES WITH INJURIES
1. Bus drivers misjudged lateral clearance 59 1
2. Bus hitting a passenger 1 2
3. Failed brakes 1 0
4. Flying debris 1 0
5. Frontal crash 4 1
6. Insufficient information 155 7
7. Nature/ Act of God 1 0
8. Other drivers misjudged lateral clearance 81 3
9. Passenger falling/ hitting self boarding, while
on or after alighting bus
1 6
10. People opening car doors hitting side of bus 15 0
11. Rear crash 16 6
12. Rear and frontal crash 1 1
13. Sideswipe crash 2 1
14. Turning corners, interfering with other
vehicles
5 0
15. Vehicles cutting in front of buses or trying to
squeeze around their sides
16 3
Total number of incidents 359 31
We also observe from the table the enormously large number of records for which there was
insufficient information in the database to ascertain either what the bus was doing at the time of
the incident or the point of impact on the bus. These “ insufficient information” records account
for approximately 42% of the 390 records in the database.
31
Furthermore, the only information regarding the severity of the injuries contained in the database
were phrases such as “ transported to hospital”, “ serious injury”, “ refused medical attention”, and
“ refused hospital transport”. Approximately one- third of the 31 incidents with injuries resulted in
either a trip to the hospital ( we have no follow- up information on the severity of such injuries) or
mention of the word “ serious” in the records. Of the 9 incidents classified as either a front, rear,
or side crash, two were described in the database with the phrase “ transported to hospital”,
otherwise either no description was given or the phrase “ refused medical attention” was used.
The next stage of the analysis was to focus on those incidents that took place on one of the four
east- west streets ( Madison, Washington, Adams, or Jackson) and to account for the 162 incidents
that were initially classified as “ insufficient information”. For the “ insufficient information”
incidents, we redistributed them among the remaining types, i. e., types 1- 5 and 7- 15, consistent
with the percentage distribution for these incidents. After this redistribution, we scaled down the
number of incidents from the entire Loop to the four streets previously mentioned— the focus of
this analysis. The results of this two- stage redistribution and scaling are shown in Table 3.8.
TABLE 3.8 Distribution of Incident Types on Four Arterials in the Loop in 2002 After
Redistribution and Scaling
INCIDENT TYPE NO INJURIES WITH INJURIES
1. Bus drivers misjudged lateral clearance 36 0
2. Bus hitting a passenger 1 1
3. Failed brakes 1 0
4. Flying debris 1 0
5. Frontal crash 2 0
6. Nature/ Act of God 1 0
7. Other drivers misjudged lateral clearance 49 1
8. Passenger falling/ hitting self boarding, while on
or after alighting bus 1 3
9. People opening car doors hitting side of bus 9 0
10. Rear crash 10 3
11. Rear and frontal crash 1 0
12. Sideswipe crash 1 0
13. Turning corners, interfering with other vehicles 3 0
14. Vehicles cutting in front of buses or trying to
squeeze around their sides 10 1
Total number of incidents 123 11
We also observe that there is one incident that was classified as both a rear and frontal crash and
so is counted in both those categories. In summary, we have derived the following distribution of
frontal, rear, and side crashes with and without injuries on the four east- west streets in the Loop
( Table 3.9).
32
TABLE 3.9 Distribution of Crashes on Four Arterials in the Loop
No Injuries With Injuries
Frontal 3 0
Rear 11 3
Side 1 0
The next stage of the analysis is to evaluate the return on investment from having CTA equip
their buses, that is, those buses running on the four east- west Loop arterials. There are several
parameters to consider for this evaluation. To assess the benefits associated with equipping CTA
buses with these collision warning systems, we require an estimate for the cost of such crashes,
but these data are not available from CTA. In the absence of such data, we have relied on other
data that are available, even though they apply to different transit properties.
According to Reference 3- 11, the average cost over five California transit agencies of frontal,
rear, and side crashes is $ 9,221, $ 1,128, and $ 3,353, respectively. We assume that these costs are
for non- injury crashes. To estimate the costs of equipping CTA buses with these three systems,
we require the cost of equipping each type of system and the number of buses that would need to
be equipped. Based on current knowledge of such systems and what is likely to be implemented
in 2010, we estimate that the cost of equipping one bus with frontal, rear, or side collision
warning systems will cost, respectively, $ 2,000, $ 2,500, and $ 500. Even if such collision
warning systems were to be implemented on buses together as a single forward- rear- side
collision warning system, it is unlikely that there would be significant economies of scale or
synergistic effects whereby the integrated system would be much less expensive than the sum of
the individual costs for the three systems implemented separately.
We assume a 15- year lifetime for each bus and equipment and a 7% discount rate. We have to
estimate the total benefits associated with the implementation of each of the three types of
collision warning systems over the course of the 15 years. These benefits depend on the crash
profile ( Table 3.9), which we assume here will follow that for the year 2002, that is, as given by
the number of crashes for each type of crash in Table 3.
Based on peak period headways for the bus routes traveling on the four arterials, we have estimated there to be 1654
buses that would have to be equipped with front, rear, and side collision warning systems. From Table 3.9, only rear
crashes involved injuries and initially we assume that these were not serious injuries and so we initially used the
same average cost for a rear crash with or without injuries, i. e., $ 1,128 per rear crash. Initially we derive the
following results, shown in Table 3.10.
4 We estimated the number of buses needed to service a route in the PM peak by following these steps for each
route:
1. Determined loop runtime of the route from CTA bus schedule
2. Determined frequency of buses on the route
3. Assumed layover of one headway or minimum 10 minutes except in the case when buses operate more
frequently than one bus every 10 minutes in which case we allowed for a layover of two headway periods.
4. Assumed that there is 1 backup bus for every 10 buses based on estimating the number of buses needed
from the schedule and comparing this value with the data that the team collected out in the field.
5. Calculate number of buses needed = { loop run time + layaway}/ frequency + backup buses
33
TABLE 3.10 Net Benefits and B/ C Ratio for Collision Warning Systems
Interest rate 0.07 0.07 0.07
Lifetime ( years) 15 15 15
Total benefits $ 27,663 $ 15,790 $ 3,353
Number of buses 165 165 165
Cost per bus $ 2,000 $ 2,500 $ 500
Total cost -$ 330,000.00 $ 412,500.00 -$ 82,500.00
Present value of benefits $ 251,956.14 $ 143,810.58 $ 30,536.11
Net benefit ($ 78,043.86) ($ 268,689.42) ($ 51,963.89)
B/ C ratio 0.76 0.35 0.37
From Table 3.10, we see that the return appears not to be worth the investment for the three
crash types. However, the B/ C ratios for the different kinds of crashes are within a factor of one
of each other, so the investment decisions are “ borderline” for each type of collision warning
system, within the margin of error based on the uncertainties in the analysis. Recall that our
sample size is small and with the presence of more injuries or more serious injuries, the costs are
going to be considerably greater and the resultant total benefits would increase, thus making the
net benefit increase as well.
3.4.2.2 Precision Docking
Since precision docking is a relatively new transit service function and not widely used, there are
definitive quantitative sources of data that can be cited about its benefits. There are two primary
kinds of benefits it can offer:
( a) Improving the amenity value and status of bus transit, by making it more like rail transit.
This is particularly difficult to quantify, but in the long term it should be manifested as a
ridership increase. In the absence of precision docking, an alternative way of providing the
“ gapless” boarding of a bus, without passengers having to step across a gap or up a step, would
be by deploying the wheelchair ramp for passengers to board from the curb. PATH has
measured the time needed to do this on its New Flyer buses, and has found the complete cycle to
extend and retract the simplest flip- style ramp to be 30 seconds. This would be a significant
penalty to bus travel time, but provides an indication of how this amenity value could be
provided in the absence of precision docking.
( b) Reducing the time needed for passenger boarding and alighting. This should be easier to
quantify, but there are no references available to provide specific values for time saved. The
actual time saving will depend on many factors, and is likely to have large variability across
transit properties, as well as from stop to stop within the same property. The factors that will
influence the boarding and alighting times include:
• Low floor or high floor bus
• Fare payment policy ( off- board, onboard cash or card)
• Door- use policy for boarding and alighting
34
• Bus positioning at stop ( closeness to curb, presence of obstacles, snow, or running water
in gutter, height and condition of curb)
• Weather conditions
• Passenger mix, including proportion of:
o Young and agile
o Parents escorting children
o Elderly and frail
o Carrying packages
o Wheelchair- bound or on crutches
It is not practical to develop a comprehensive data set to address all of these issues. Precision
docking has an obvious direct influence on the bus positioning at the stop, and its potential for
time saving will depend heavily on the passenger mix, which is a variable that is impossible to
control. In order to focus attention on the effect of precision docking rather than the other
influences on boarding and alighting time, we will assume that it will be applied only to the
newer low- floor buses. While off- board fare payment and flexible door- use policies can speed
up boarding and alighting and can be recommended in general to reduce dwell times at stops,
their potential interactions with precision docking are beyond the scope of the current evaluation.
The cost- effectiveness of precision docking in the Loop Area can be addressed from two
different perspectives. On the one hand, after estimating the costs of implementing the docking
capability, we can estimate how much time saving would be sufficient to “ break even” over the
lift of the bus. On the other hand, we can estimate several possible credible levels of time saving
and determine what their benefit/ cost ratios would be. In the absence of hard data on time
savings, we will bound the problem by approaching it from both directions.
The systems that enable buses to be steered automatically, both at bus stops for precision
docking and while driving at cruising speed, require the investment in essentially the same
elements on the buses and the roadway infrastructure: reference markings to define the desired
path of the bus and the following in- vehicle components: lateral position sensors, steering
actuator, control computer and driver interface. The reference markings and position sensors can
be based on a variety of different technologies, but the other elements are largely unaffected by
the choice of technology. At PATH, we have experimented with magnetic, machine vision and
GPS systems for the reference/ sensing technologies and have found the magnetic system to
provide the highest accuracy and robustness, which is particularly critical for the performance
needed to provide precision docking.
The costs of the in- vehicle components are very sensitive to the number of units produced,
particularly because of the need to amortize up- front development costs. We have estimated
these costs for two different assumed rates of annual production of vehicle guidance systems
( which could include trucks as well as buses). These represent higher costs in the near term,
when production volumes are lower, and lower costs in the long term, when the production
volumes are higher, as shown in Table 3.11
35
TABLE 3.11
Unit Costs of Precision Docking Technologies
Element Production of Hundreds
( near term)
Production of Ten
Thousand
( long term)
Steering actuator $ 2500 $ 500
Magnetic sensors $ 5000 $ 1000
Computer and interfaces $ 5000 $ 1000
Driver interface $ 1000 [ included]
Installation/ integration $ 500 $ 200
Total $ 14,000 $ 2700
Thus we estimate the cost per bus of implementing precision docking to be about $ 14 K in the
relatively near term. The infrastructure improvements needed to complement the vehicle
improvements are two: installation of reference markings at the bus stops and construction of
boarding platforms that will be level with the bus floor. If the reference markers are magnets,
their installation will likely cost about $ 500 per stop ( 50 magnets at $ 10 each), and the boarding
platform could add another $ 2000 per stop. For the routes serving the two one- way pairs of
streets under consideration, there will be about 24 bus stops to equip, for a total cost of about $ 60
K. If this cost is assigned to 165 buses providing the cross- town services in the Loop, it will add
an average of about $ 360 to the cost per bus. In order to be conservative, we round up the cost
per bus to $ 15 K.
The eleven cross- town Loop bus routes have different numbers and patterns of stops and
different route lengths. Without going into intimate detail on each route, we estimate that on
average each bus makes 12 stops on its east- west round trip through the Loop Area, and does an
average of 8 round trips per day, for a total of 96 daily stops. With about 260 weekdays of
annual operation, plus a lower level of weekend service, we can estimate an average of
approximately 300 annual operating days of 96 stops for each bus, for an annual total of 28,800
stops.
CTA reports an average operating cost of $ 81.64 per hour for its buses, which should be the
minimum consideration in the value of time saved by precision docking at the bus stops.
However, the value of time of the passengers on those buses should not be ignored. In the
absence of hard data on the occupancy of the buses in the Loop Area, we can estimate several
different occupancy levels for consideration: 10, 20 or 40 passengers. At a value of time of $ 10
per hour per passenger, these would add $ 100, $ 200 and $ 400 per hour respectively to the direct
CTA operating cost savings.
“ Break- even” Analysis
Using a discount rate of 7%, and a bus life of 15 years, the $ 15 K per bus cost of implementing
precision docking is amortized into an annual cost of $ 1647. This could be a “ break- even”
investment based on the following time savings ( annually and per bus stop) in Table 3.12
36
TABLE 3.12 Time Savings: Annually and Per Bus Stop
Annual Hours Saved Seconds Saved per Stop
CTA Direct costs @ $ 81.64 20.17 2.52
CTA+ 10 passengers @ $ 181.64 9.07 1.13
CTA+ 20 passengers @ $ 281.64 5.85 0.73
CTA+ 40 passengers @ $ 481.64 3.42 0.43
So, even very small amounts of time saved at each bus stop from precision docking could be
found cost effective, particularly when the value of passenger time savings is added to the direct
operating cost savings by CTA.
Sensitivity Analysis Based on Assumed Docking Time Savings
The Transit Capacity and Quality of Service Manual ( 3- 12) provides information on passenger
boarding and alighting times for North American LRT services that can shed light on the
potential for time savings from precision docking. These results show that access directly from
the platform to the vehicle interior saves 1.5 sec/ pass if all the passenger flow is in one direction
( boarding or alighting) and 3.2 sec/ pass when the flow is in both directions, compared to
stepping up three steps from street level. Even a conservative use of this data to estimate time
savings for precision docking could show significant benefits. If we assume a low- floor bus with
a single step from ground to bus floor and assume that the time saving in this case would
therefore only be 1/ 3 as large as it is for the three steps up into an LRT vehicle, the time saving
per passenger would still be 0.5 seconds for one- direction passenger flow and 1.0 seconds for
two- way flow. At the passenger flow rates per bus stop for the CTA routes in the Loop area, this
would indicate a time saving per stop of at least 2 to 3 seconds with uni- directional passenger
flow and twice that amount with bi- directional passenger flow per door.
We hypothesize several possible levels of time saving to see the sensitivity of the benefits and
B/ C ratios to these time savings. We have selected values of 5 and 10 seconds per stop as the
primary sensitivity estimates, to allow for a mixture of cases in which most travelers save a
fraction of a second, while others could save several seconds based on their mobility limitations.
In addition, we have included a more extreme case of 30 seconds per stop to represent the
“ comparable amenity level” associated with deployment of the wheelchair ramp at each stop
( recognizing that such a large additional delay at each stop would not be acceptable to most
passengers).
Using the same value of time and docking system cost estimates as in the previous analysis, the
savings and B/ C ratios for these cases are in Table 3.13
37
TABLE 3.13 Savings and Benefit- Cost Ratio Findings: Near- Term Precision Docking
Time Saved
per Stop ( s)
CTA Saving Avg.
Pass.
Load
Passenger
Saving
Annual Saving
Total per Bus
B/ C
5 40 hr = $ 3265 10 $ 4000 $ 7,265 4.4
5 40 hr = $ 3265 20 $ 8000 $ 11,265 6.8
5 40 hr = $ 3265 40 $ 16000 $ 19,265 11.7
10 80 hr = $ 6530 10 $ 8000 $ 14,530 8.8
10 80 hr = $ 6530 20 $ 16000 $ 22,530 13.7
10 80 hr = $ 6530 40 $ 32000 $ 38,530 23.4
30 240 hr = $ 19590 10 $ 24000 $ 43,590 26.5
30 240 hr = $ 19590 20 $ 48000 $ 67,590 41
30 240 hr = $ 19590 40 $ 96000 $ 115,590 70.2
Regardless of the potential benefits that could be gained from saving time and improving the
quality of bus service using precision docking, CTA has some serious concerns about the
practicality of implementing the docking capability on the Loop area streets that must be shared
with a multitude of other users and services. CTA is concerned that it will be difficult to
implement precision docking, or to gain its benefits even it if is implemented, for reasons
including:
• Sidewalks are narrow and cluttered, making it difficult to find space for the raised
loading platforms that would be needed to provide seamless transfers from curbside to
the bus floor;
• Raised loading platforms in this crowded environment could be a hazard for pedestrians;
• It is difficult to specify bus stopping locations precisely in this environment because of
the closely bunched operations of the multiple bus routes, which sometimes require as
many as four buses to access a stop on the same block at the same time;
• Buses often have difficulty accessing the stopping locations because of interference from
parked vehicles or vehicles queued to make right turns at intersections, where they are
often blocked by pedestrians crossing the streets;
• The curb areas are not well maintained and are subject to obstruction by debris, including
snow, sometimes making it difficult for buses to pull up immediately adjacent to the
curb.
3.4.2.3 Transit Signal Priority
Transit Signal Priority ( TSP) in its simplest form makes it possible for a bus approaching an
intersection during the final seconds of the green signal cycle to request an extension of the
green cycle so that the bus can pass through before the signal turns red, thereby saving the bus
38
and its passengers the red cycle time. This tends to provide some ancillary time saving benefits
to the other vehicles traveling in the same direction as the bus, while increasing the time delays
to the crossing traffic ( 3- 13).
The Loop area is more amenable to potential use of TSP than many other areas because its
streets are on a rectilinear grid and its traffic signalization pattern is currently very simple, with
all signals simultaneously switching between green for north- south traffic and green for east-west
traffic. More sophisticated signal patterns, particularly those with progressive “ green
waves”, would significantly complicate the design and evaluation of TSP alternatives. With the
current signalization scheme, delaying the onset of red for an east- west bus at one intersection
would provide some modest gains for the other east- west traffic on that street and some modest
delays for the north- south traffic on the cross- street. If the cross- street traffic volume is
significantly larger than the east- west volume, there could be net negative effects on area traffic.
However, the available data for the Loop area indicates relatively equal traffic flows on the
north- south streets and the east- west streets that have the bus lanes. The exceptions are
Dearborn and State Streets, which carry significantly larger traffic volumes than the east- west
streets with the cross- town bus lines, so perhaps TSP should not be applied ( or should be applied
more conservatively) at the intersections with those streets.
A detailed evaluation of traffic impacts should be done before implementation of any TSP
scheme, but here we are doing a more general and preliminary evaluation of the potential
benefits from TSP. At this level of analysis, it appears to be reasonable to assume that the
effects on traffic other than the buses will generally cancel each other out for the north- south and
east- west traffic, so attention can be focused on the potential time savings for the buses and their
passengers.
A short yet informative summary of only the through traffic at intersections on the four arterials
show that the north- south running streets carry traffic that is often greater than that carried by the
east- west arterials ( Tables 3.14 and 3.15).
TABLE 3.14 Through Traffic at Intersections in the Loop
Canal Upper
Wacker
Upper
Wacker
Frankli
n
Well
s
La Salle Clark Dearbor
n
State Wabas
h
Michigan
↑ ↓ ↑ ↑ ↓ ↓ ↑ ↓ ↑↓
Washingt.
→
cross street
910
570
1050
800
930
870
1145
850
1250
560
1200
↑ 450/↓ 62
5
1475
1505
850
985
705
↑ 350/↓ 490
965
620
↑ 1210/↓ 162
5
Madison ←
cross street
1195
840
885
580
915
760
860
870
900
680
680
↑ 445/↓ 53
0
700
1185
670
1135
640
↑ 530/↓ 590
645
725
↑ 1160/↓ 167
0
Jackson →
cross street
555
770
890
400
690
280
575
860
990
1485
545
􀂪 775
1260
1165
595
980
585
↑ 605/↓ 540
985
800
360
↑ 1075/↓ 112
5
Adams←
cross street
765
700
650
500
660
430
300
420
580
525
480
↑ 420/↓ 36
0
665
1245
675
1380
915
↑ 1100/↓ 74
0
645
670
↑ 1170/↓ 126
5
39
In each cell the upper number is the through traffic from east- west direction and the lower
number is the through traffic on the north/ south direction. Most streets are one- way, except for
Wacker, La Salle, State, and Michigan. These traffic volumes do not include turning traffic,
only through traffic. Yellow highlights the higher traffic volume direction.
TABLE 3.15 All Traffic ( Through and Turning) at Intersections in the Loop
Canal Upper
Wacker
Upper
Wacker
Frankli
n
Well
s
La Salle Clark Dearbor
n
State Wabas
h
Michigan
↑ ↓ ↑ ↑ ↓ ↓ ↑ ↓ ↑↓
Washingt.
→
cross street
1010
805
1150
890
1140
970
1275
1165
1450
760
1450
↑ 650/↓ 82
5
1650
1785
1120
1155
1010
↑ 420/↓ 535
1170
785
820
↑ 1210/↓ 162
5
Madison ←
cross street
1280
1225
1045
825
1005
890
1045
1025
1015
880
950
↑ 540/↓ 72
5
935
1355
880
1400
640
↑ 630/↓ 720
865
925
↑ 1670/↓ 194
5
Jackson →
cross street
739
915
1035
550
890
315
760
995
1180
1580
735
􀂪 775
1430
1325
835
1050
730
↑ 790/↓ 595
1320
945
805
↑ 1340/↓ 119
0
Adams←
cross street
1345
700
730
760
800
455
470
570
655
715
665
↑ 460/↓ 49
5
855
1460
900
1625
990
↑ 1275/↓ 88
5
850
870
↑ 1670/↓ 159
0
In this table all traffic ( through and turning) from indicated direction is included ( pink marks
where higher volume direction changes).
Even though the traffic volumes in the North- South and East- West directions are of comparable
magnitudes, it is important to keep in mind that each bus is carrying many more passengers than
each passenger car. So, giving priority to a bus to avoid a red light ( and saving all of its
passengers an amount of time at least the length of the red cycle) is going to produce more
benefits than the costs associated with a few seconds of delay to the car drivers waiting slightly
longer for their green signal on the cross street. Because the traffic signal cycles in the Loop
area tend to simultaneously provide green lights to all north- south traffic and then to all east-west
traffic ( rather than using more complicated “ green wave” progressions), there is no reason
to expect significant disruptions to cross traffic from a delay of a few seconds to permit a bus to
traverse an intersection.
The key parameter in the design of a TSP scheme is the length of the “ window” during which the
green cycle would be held for a bus. In the Wilshire- Whittier BRT corridor in Los Angeles, they
selected 10% of the signal cycle time. In the Loop Area, the signal cycle time is 75 seconds, and
10% of that would be 7.5 seconds, so we can look at the sensitivity of the results to windows of 5
and 10 seconds to surround this central value.
With relatively similar traffic volumes on most of the north- south and east- west streets in the
Loop Area, a first approximation to the traffic signal cycle would be 35 seconds of green, 35
seconds of red and 5 seconds of amber for each direction. For any vehicle approaching an
intersection, its probability of green is 35/ 75. However, a bus with 5 or 10 seconds of signal
priority window could extend this to 40 or 45/ 75 respectively. Each red light avoided in this way
40
saves the bus the length of the red cycle ( 35 seconds) plus time needed to re- accelerate to speed
( perhaps another 10 seconds).
With nine intersections to pass in going across the Loop, each bus has an expected value of
9x35/ 75 red lights to encounter without signal priority, and each of those red lights will cost an
average of 45 seconds of additional travel time. This represents an average traffic signal delay
of 189 seconds for a one- way Loop traversal, or 378 seconds for a round trip. If we assume that
signal priority is available at seven of those intersections ( all except State and Dearborn), then
the expected number of red lights is [ 2x35/ 75 + 7x30/ 75] for a 5- second priority window and
[ 2x35/ 75 + 7x25/ 75] for a 10- second priority window. These represent average traffic signal
delays of 336 seconds and 294 seconds respectively for the Loop round trips, or average savings
of 42 and 84 seconds respectively.
The observational data reported by UIC implies that red traffic signals were an impediment to
buses leaving their stops only 17% of the time. However, the same data reported 39% of the
stops being “ normal”, without indicating whether those also involved red traffic signals or
whether th