ISSN 1055- 1425
May 2010
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 6206
CALIFORNIA PATH PROGRAM
INSTITUTE OF TRANSPORTATION STUDIES
UNIVERSITY OF CALIFORNIA, BERKELEY
Develop Methods to Reduce or
Prevent Backing Crashes
UCB- ITS- PRR- 2010- 30
California PATH Research Report
Douglas L. Cooper, Sarah Duffy,
Phyllis Orrick, David R. Ragland
CALIFORNIA PARTNERS FOR ADVANCED TRANSIT AND HIGHWAYS
i
Develop Methods to Reduce or
Prevent Backing Crashes
Prepared for: the
California Department of Transportation
Task Order: 6206
Prepared by: Douglas L. Cooper, Sarah Duffy,
Phyllis Orrick, and David R. Ragland
May 2009
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________________________________________________________________________
University of California Berkeley
Traffic Safety Center
ii
The mission of the UC Berkeley Traffic Safety Center is to reduce traffic fatalities and
injuries through multi- disciplinary collaboration in education, research, and outreach and
to strengthen the capability of state, county, and local governments, academic
institutions, and local community organizations to enhance traffic safety through
research, curriculum and material development, outreach, and training for professionals
and students.
The Traffic Safety Center stores all of its internally published research papers in the
eScholarship repository of the California Digital Library, which is hosted by the
University of California. To view reports and download them as PDFs, please visit our e-
Repository site at http:// repositories. cdlib. org/ its/ tsc/. Or you can visit our Web site at
http:// www. tsc. berkeley. edu/ publications.
UC Berkeley Traffic Safety Center
2614 Dwight Way
Berkeley, CA 94720- 73734
www. tsc. berkeley. edu
tscenter@ berkeley. edu
Cover photograph is the copyright property of the California Department of Transportation
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Acknowledgments
This work was performed by the UC Berkeley Traffic Safety Center in conjunction with
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.
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Abstract
Workplace motor vehicle incidents at Caltrans are a significant cause of injuries,
employee lost time, and property damage. Because backing crashes are major
contributors to motor vehicle incidents, identifying and promoting methods of reducing
backing accidents is a top priority. According to internal Caltrans’ data, 92.3% of
workplace backing crashes were preventable by the driver. Backing crashes are the single
largest category of preventable crashes, representing 30% of preventable crashes in the
Caltrans fleet. From 1998 through 2007, preventable backing crashes cost Caltrans at
least $ 5.45 million in vehicle repairs alone.
The Traffic Safety Center ( TSC) at the University of California- Berkeley completed this
study, which examines Caltrans crash data from the Safety Information Management
System ( SIMS) and identifies trends in backing- related crashes. The findings describe
how these crashes are distributed across Caltrans sites, various work locations, and
among vehicle types. This study also presents a summary of a literature review of
technological solutions to backing crashes, a summary of results from a Caltrans backing
prevention technology pilot, and an outline for a proposed Field Operational Test of
promising backing technologies. Based on careful review of Caltrans data and backing
incident counter- measures, the study evaluates current Caltrans safety policies relevant to
backing crashes and offers recommendations for strengthening them.
Keywords: Human Factors, Risk Analysis, Vehicles, Work Zone Safety
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Table of Contents
Acknowledgments.......................................................................................................... iii
Abstract ......................................................................................................................... iv
Table of Contents............................................................................................................ v
List of Figures, Tables, and Appendices ......................................................................... vi
Executive Summary ...................................................................................................... vii
1 Introduction............................................................................................................... 1
2 Crash Data ................................................................................................................ 2
2.1 SIMS Database Inputs ........................................................................................ 2
2.2 Preventable Backing and Non- Backing Crashes.................................................. 2
2.3 Backing Crash Locations .................................................................................... 3
2.3.1 Statewide ..................................................................................................... 3
2.3.2 Backing Crashes by District ......................................................................... 4
2.4 Types of Vehicle Involved in Backing Crashes ................................................... 8
3 Information Management: Suggestions for Current and Future Practices ................. 12
3.1 Improvements Needed in Filling Out Forms ..................................................... 12
3.1.1 Incomplete Information.............................................................................. 12
3.1.2 Incorrect Information................................................................................. 12
3.2 Suggested Improvements in Clarity, Structure, and Functionality of Forms and
SIMS Database.......................................................................................................... 13
3.2.1 Clarify Confusing Incident Location Fields................................................ 13
3.2.2 Additional Data Needs............................................................................... 14
3.3 Suggested Improvements in Data Collection, Entry, Database Access, and
Accident Investigation Training ................................................................................ 15
3.3.1 Data Collection Lessons from Other State Departments of Transportation
( DOTs).................................................................................................................. 15
4 Caltrans Policies and Procedures ............................................................................. 17
4.1 Caltrans Manuals .............................................................................................. 17
4.2 Spotters’ Guide................................................................................................. 18
4.3 Accountability, Discipline, and Work Rules ..................................................... 18
4.4 Zero Incidents................................................................................................... 21
5 Other Approaches for Possible Incorporation .......................................................... 23
6 Technology Solutions.............................................................................................. 24
6.1 Findings of the Literature Review..................................................................... 24
6.2 Rear Radar Detection Devices Currently Installed in Caltrans Vehicles ............ 26
7 Conclusions............................................................................................................. 27
8 References............................................................................................................... 28
9 Appendices.............................................................................................................. 30
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List of Figures, Tables, and Appendices
Figure 1: Backing Crashes as a Share of All Preventable Crashes 1998- 2007 .................. 2
Figure 2: Preventable Backing Collisions by Location 1998- 2007................................... 4
Figure 3: Total Number Preventable Backing Crashes by District 1998- 2007.................. 5
Figure 4: Percentage of Preventable Backing and Preventable Non- Backing Crashes by
District 1998- 2007................................................................................................... 5
Figure 5: Preventable Backing Crashes by District Normalized for Number of Vehicles
1998- 2007 ............................................................................................................... 6
Figure 6: Preventable Backing Crashes Per 100,000 Miles by District 1998- 2007 ........... 7
Figure 7: Preventable Backing Crashes in Caltrans Yards by District 1998- 2007............. 7
Figure 8: Preventable Backing Crashes 1998- 2007 per 100 Vehicles in Caltrans Yards by
District .................................................................................................................... 8
Figure 9: Number of Preventable Backing Crashes by Vehicle Type 1998- 2007.............. 9
Figure 10: Preventable Backing Crashes by Vehicle Type Normalized for Number of
Vehicles 1998- 2007............................................................................................... 10
Figure 11: Average Annual Number of Cargo- Body Vehicle Preventable Backing
Crashes by District 1998- 2007............................................................................... 11
Figure 12: The Preco PreView ™ Display...................................................................... 26
Table 1: Overall Preventable Backing vs. Non- Backing Crashes
by Location 1998- 2007............................................................................................ 3
Appendix A: Accident Identification Card Form STD. 269 ............................................ 30
Appendix B: Vehicle Accident Report Form STD. 270 ................................................. 31
Appendix C: Data Input for Motor Vehicle Accident Form PM- S- 0270 ........................ 33
Appendix D: Backing Sections of Caltrans Safety and Maintenance Manuals ............... 35
Appendix E: Backing and Spotters Guide...................................................................... 37
Appendix F: Caltrans Vehicles Installed with Preco Rear Radar Systems ...................... 39
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Executive Summary
This study examined motor vehicle incident data collected between 1998 and 2007 from
Caltrans’ Safety Information Management System ( SIMS), the repository for safety data
available for statistical analysis at Caltrans. During this period, preventable backing
crashes cost Caltrans at least $ 5.45 million in vehicle repairs alone; this figure does not
include medical costs, employee lost time, vehicle lost time, and third- party expenses.
According to Caltrans’ investigations, 92.3% of backing crashes could have been
prevented by the driver, compared with 47% of non- backing crashes. Because most are
preventable, these crashes represent a readily accessible opportunity for enhancing safety
and saving money.
To eliminate backing crashes there are essentially three approaches that can be taken:
1. Changes to equipment ( e. g., mirrors, backing video, radar/ sonar).
2. Adjustments to procedures ( e. g., use of cones, circle checks, spotters).
3. Changes in workplace safety policies ( e. g., training, accountability).
While this report will discuss all three approaches, emphasis will be on procedures and
policies since these are applicable to all vehicles, and do not require capital outlay.
The starting point for solving the backing crash problem is to gain a clear understanding
of its magnitude and scope, and the SIMS database was used to provide the data for a
descriptive statistical analysis of motor vehicle incidents at Caltrans.
In addition, TSC staff conducted a review of the Caltrans safety divisions’ current data
collection and analysis procedures, and conducted interviews with Caltrans district safety
officers and safety representatives from other state departments of transportation ( DOTs).
This research formed the basis for recommendations to improve backing safety at
Caltrans including the following:
• Creating procedures to ensure accident reporting forms are filled out completely and
accurately before contents are entered in the database.
• Establishing a linkage between SIMS data and other internal Caltrans safety- related
data, such as departmental personal injury files.
• Combining SIMS injury data State Compensation Insurance Fund ( SCIF) data.
• Providing supervisors and staff with uniform training in accident and injury
investigation and in completing forms.
• Establishing uniform procedures and deadlines for filing reports.
• Limiting database access to personnel trained in the software that runs the database
and ensuring that district safety officers are trained in this software use.
• Instituting an effective progressive discipline policy that enforces meaningful
consequences for employees who cause preventable incidents.
• Exploring merit rating policies, which include both an “ experience rating” and a
“ schedule rating,” as well as regional analysis of claims.
• Conducting a Field Operational Test to evaluate promising technologies.
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1 Introduction
From 1998 through 2007, the most recent ten years for which data are available, Caltrans
drivers were involved in 2,926 backing crashes, 93.2% of which were determined to have
been preventable by the driver. In contrast, only 47% of non- backing crashes were
determined to be preventable by the driver.
The estimated average repair cost for each involved vehicle is $ 2,000, based on 2006
costs to repair the 45 vehicles for which this information is available. Based on this
estimate, over the decade studied, preventable backing crashes cost Caltrans at least
$ 5.45 million in vehicle repairs alone; this is not counting medical costs, employee lost
time, vehicle lost time, and third- party expenses.
Because these crashes are largely preventable, they represent a readily accessible
opportunity for enhancing safety and saving money.
There are essentially three approaches that can be taken to eliminate backing incidents.
These involve changes to:
1. Equipment ( e. g., mirrors, backing video, radar/ sonar).
2. Procedures ( e. g., use of cones, chocks, spotters).
3. Policy ( e. g., training, accountability).
While this report will discuss all three approaches, it will emphasize procedures and
policies since they are applicable to all vehicles, and do not require capital outlay.
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2 Crash Data
2.1 SIMS Database Inputs
The SIMS database contains information obtained from three forms that are filled out
each time a Caltrans vehicle is involved in an incident:
• Form STD. 269, “ Accident Identification Card” ( Appendix A) is completed by the
driver at the scene and turned over to the driver’s first- line supervisor.
• Form STD. 270, “ Vehicle Accident Report” ( Appendix B) is typically completed by
the driver upon returning to the office and turned over to the driver’s first- line
supervisor.
• Form PM- S- 0270, " Data Input for Motor Vehicle Accident” ( Appendix C) is a
computer input document completed by the first- line supervisor based on information
provided by the driver and the results of an investigation ( Caltrans 1996a [ section
revised 2000]). This form contains criteria used to determine whether the driver could
have prevented the crash.
2.2 Preventable Backing and Non- Backing Crashes
Figure 1 shows the ten- year trends for preventable backing and non- backing crashes. In
2006, both categories of crashes began a reversal of a multi- year downtrend. When
examining the vehicle’s action just prior to the crash (“ Movement Preceding Collision”),
of the 18 possible choices on the data input accident form, “ backing” was found to be the
single most common, accounting for approximately 30% of total preventable crashes.
This was followed by “ Driving Straight Ahead” ( 25.4%) and “ Stopped” ( 10.5%).
Figure 1: Backing Crashes as a Share of All Preventable Crashes 1998- 2007
Source: Caltrans SIMS Database
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2.3 Backing Crash Locations
2.3.1 Statewide
A comparison of preventable backing and non- backing crashes by general location ( see
Table 1) shows that across all Caltrans districts, the single location where preventable
backing crashes occur most often ( 24.6% of the time) is “ State Yard or State Property”
( as indicated on Form PM- S- 0270), followed by “ Private Property” at 13.9%, and
“ Freeway” at 13.8%. For non- backing crashes, these percentages are 17.2%, 7.3%, and
19.7% respectively.
However, the general location category “ State Yard or State Property” is not well defined
since several other general accident location choices ( e. g., “ Conventional Highway”) can
also be considered state property, and there is no assurance of consistency in how crashes
are assigned to general location categories.
Table 1: Overall Preventable Backing vs. Non- Backing Crashes by Location
1998- 2007
Backing Non- backing
GENERAL LOCATION Number % Number %
City Street 286 10.5% 1,235 19.5%
Construction 186 6.8% 244 3.9%
Conventional Highway 216 7.9% 843 13.3%
Freeway 376 13.8% 1,248 19.7%
Freeway Ramp or Connector 195 7.2% 578 9.1%
Lane or Shoulder Closure 191 7.0% 198 3.1%
Maintenance Work Zone 159 5.8% 202 3.2%
Private Property 378 13.9% 465 7.3%
Rural Road 39 1.4% 149 2.4%
State Yard or Property 670 24.6% 1,091 17.2%
Tunnel or Tube 2 0.1% 8 0.1%
( blank) 28 1.0% 74 1.2%
Total 2,726 100.0% 6,336 100.0%
Source: Caltrans SIMS Database
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In addition to the 11 general location categories listed in Table 1, Form PM- S- 0270 offers
eight specific location designations, including “ Parking Lot.” To obtain a clearer
understanding of those backing incidents that occur in the general location “ State Yard or
Property,” Figure 2 breaks the category down into two subcategories: “ Parking Lot” and
“ Other.” The assumption here is that “ Parking Lot” refers to Caltrans yards. Subdivided
in this way, it can be determined that Caltrans yards account for the largest location
category ( 20%) of backing incidents.
Figure 2: Preventable Backing Collisions by Location 1998- 2007
Source: Caltrans SIMS Database
2.3.2 Backing Crashes by District
The total number of preventable backing crashes that occurred between 1998 and 2007
varies dramatically by district ( Figure 3), with the highest number in Districts 4 ( Bay
Area) and 7 ( Los Angeles) and the lowest numbers in District 32 ( Headquarters) and 9
( Inyo County). Given the differences in district size and number of vehicles in use in each
district, this variation is understandable. Information on employee populations, job
assignments, and distribution among the districts is needed to gain a clearer picture of the
factors that contribute to the variations. The requirement for additional data is discussed
further in Section 3.2.2: Additional Data Needs.
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Figure 3: Total Number Preventable Backing Crashes by District 1998- 2007
Source: Caltrans SIMS Database
The proportion of preventable backing crashes versus preventable non- backing crashes
also varies among districts ( Figure 4), with the highest proportion of backing crashes in
District 6 ( Fresno), with 44%. In the majority of districts, on average, 35% of preventable
crashes involved backing.
Figure 4: Percentage of Preventable Backing and Preventable Non- Backing
Crashes by District 1998- 2007
Source: Caltrans SIMS Database
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Figure 5 shows the number of preventable backing crashes normalized by the number of
vehicles in each district. While displaying less variability than the non- normalized
numbers, these figures reveal large variations among Caltrans districts. Further research
regarding specific vehicle types and usage ( e. g., mileage, road, and weather conditions)
in the different districts would help clarify the causes of variation among the districts.
Figure 5: Preventable Backing Crashes by District Normalized for Number of
Vehicles 1998- 2007
Source: Caltrans SIMS Database
Because this variability between districts could be attributable, at least in part, to the
differences in miles the vehicles are driven, we calculated the number of incidents per
100,000 miles driven. Mileage information is a rough estimate derived from data
collected on an ad hoc basis from the Division of Equipment’s vehicle repair records. The
analysis results are shown in Figure 6. Again, the numbers vary considerably among
districts. From 1998 to 2007, the highest number of preventable backing collisions per
100,000 miles driven occurred in District 5 ( Monterey), District 1 ( Eureka), District 2
( Redding), District 10 ( Stockton), District 11 ( San Diego), and District 12 ( Irvine). The
lowest number occurred in District 6 ( Fresno).
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Figure 6: Preventable Backing Crashes Per 100,000 Miles by District 1998- 2007
Source: Caltrans SIMS Database
The total number of preventable backing crashes that occurred in Caltrans yards also
differs significantly by district, as shown in Figure 7. Betweem 1998 and 2007, 121
preventable backing incidents occurred in District 4 ( Bay Area) compared with 68 in
District 7 ( Los Angeles). District 4 recorded a greater number of drivers and vehicles
than District 7 and may also have more pickup trucks or wreckers. More research will be
necessary to understand what might be responsible for increased rates of backing
collisions in the Bay Area.
Figure 7: Preventable Backing Crashes in Caltrans Yards by District 1998- 2007
Source: Caltrans SIMS Database
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Figure 8 illustrates the rates of yard crashes per 100 vehicles, which also vary across
districts, from a low of 1.7 in District 6 ( Fresno) to a high of 8.4 in District 32
( Headquarters). On average, there were 3.7 preventable yard backing incidents per 100
vehicles per year per district. The outsized number of yard crashes in District 32
( Headquarters), over two times the average, is a cause for concern. Further research is
needed to identify the reasons for this high crash rate.
Figure 8: Preventable Backing Crashes 1998- 2007 per 100 Vehicles in Caltrans
Yards by District
Source: Caltrans SIMS Database
2.4 Types of Vehicle Involved in Backing Crashes
Between 1998 and 2007, pickup trucks were involved in more preventable backing
crashes ( 682) than any other vehicle category, comprising 25% of all preventable backing
crashes ( Figure 9). Although this data is not normalized ( there are more pickup trucks
than other types of vehicles in the Caltrans fleet), it provides a focus for potential
remedial actions. By addressing backing problems in pickups, sedans, vans, SUVs, and
station wagons ( vehicles whose size and rear visibility are not likely to be contributing
crash factors), 37% of backing crashes could be eliminated. This could be achieved
through changes to policies and procedures and would need not involve new equipment.
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Figure 9: Number of Preventable Backing Crashes by Vehicle Type 1998- 2007
Source: Caltrans SIMS Database
When the incident data by vehicle type are normalized— that is, when the number of each
type of vehicle is taken into consideration— a different picture emerges ( Figure 10). In
this analysis the larger vehicles, many with limited visibility to the rear, have the highest
preventable backing crash rates. Wreckers have the most incidents, which could be due in
part to the backing- intensive nature of the work they perform. However, because of their
small numbers, wreckers’ high incident rates account for less than 1% of all backing
incidents, or roughly three crashes per year. Still, wrecker operations may be a productive
focus for remedial programs.
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Figure 10: Preventable Backing Crashes by Vehicle Type Normalized for Number
of Vehicles 1998- 2007
Source: Caltrans SIMS Database
As Figure 10 shows, overall crash rates for different types of vehicles vary substantially.
Crash rates by vehicle type also vary among Caltrans districts. As shown in Figure 11, for
example, the average annual crash rate for cargo- body vehicles in District 12 is three
times that of District 6. It may be that usage for these vehicles ( by miles or hours, neither
of which is currently available in the SIMS database) may be substantially higher in
District 6. Alternatively, operating methods, procedures, or factors in the working
environment may play a role. Further investigation is needed to understand factors that
impact different rates.
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Figure 11: Average Annual Number of Cargo- Body Vehicle Preventable Backing
Crashes by District 1998- 2007
Source: Caltrans SIMS Database
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3 Information Management: Suggestions for Current and
Future Practices
The SIMS database has the potential to provide information about the causes of
preventable backing crashes and to offer solutions to the problem. Based on a review of
the current SIMS database as well as interviews with Caltrans district safety officers and
safety representatives from other state departments of transportation, the TSC staff
developed the following suggestions to make SIMS a more powerful tool for safety and
prevention.
3.1 Improvements Needed in Filling Out Forms
3.1.1 Incomplete Information
A common problem with the SIMS system is that forms containing the data to be entered
into SIMS are not filled out completely. For example, in the ten- year period between
1998 and 2007, “ Basic Cause” was missing in 3,636 ( 22%) of the incidents, “ Type of
Collision” was missing in 1,087 ( 6.7%), and “ Driver’s Condition” was missing in 836
( 5.1%). Personal injury report data were also missing in several categories that are
important for statistical analysis, including: “ Hire date” ( missing on 10.5% of the forms);
“ Time of Injury” ( missing on 15%); “ Preventability” ( missing on 7%); and “ Accident
Location” ( missing on 2%). Current procedures should be reviewed to ensure that the
forms are completely filled out before the information for each incident is entered into
SIMS.
3.1.2 Incorrect Information
Another common problem is that the information that is entered is incorrect. This is
particularly apparent in the “ Movement Preceding Collision” field. Out of a sample of
100 forms in which “ Movement Preceding Collision” was described as “ Stopped,” 64
included crash narratives which contradicted this designation. The descriptions of these
crashes included such statements as:
• Employee rear- ended private vehicle at stoplight.
• State vehicle struck guardrail while backing.
• Pulled out from a stop sign and hit another vehicle.
• Caltrans vehicle rear- ended private party at railroad crossing.
Lack of understanding of the terms used in incident forms also leads to incorrect entries.
Under “ Movement Preceding Collision,” two of the choices involve the vehicle being
stationary. One is “ Stopped,” meaning that the vehicle is not moving but that the driver is
still in the vehicle, and “ Parked,” which indicates that the operator has exited the vehicle.
A significant number of entries under “ Stopped” include accident descriptions which
should be in the “ Parked” category, such as:
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• Left truck and forgot to set parking brake, vehicle rolled over an embankment.
• Employee parked in shoulder left truck running. When employee returned to vehicle
it had rear- ended contractor's vehicle.
• Operator left tractor to talk to citizen parked in work zone. Tractor was not
completely in park and rolled forward into rear bumper of parked vehicle.
Before data is entered in the SIMS database, it should be reviewed to confirm that it is
complete and that each field entry is consistent with the crash narrative.
3.2 Suggested Improvements in Clarity, Structure, and Functionality
of Forms and SIMS Database
3.2.1 Clarify Confusing Incident Location Fields
The location choices on the P- MS- 0270 form often make it difficult to ascertain accurate
locations for many incidents because the 11 “ General Location” choices do not always
correlate well when used in conjunction with the six ” Specific Locations”:
General Locations
City Street
Conventional Highway
Construction
Freeway
Freeway Ramp or Connector
Lane or Shoulder Closure
Private Property
Rural Road
State Yard or Property
Tunnel or Tube
Maintenance Work Zone
Specific Locations
At Intersection
Median
Off Street or Hwy in R/ W
On Bridge
Parking Lot
Shoulder
Traveled Way
The problem lies in the fact that incidents that occur on a “ City Street,” “ Conventional
Highway,” “ Freeway,” “ Freeway Ramp or Connector,” “ Rural Road,” or “ Tunnel or
Tube” could be recorded on the incident report in those general location categories, or
they could be placed in the general location category “ State Yard or Property,” since all
of these locations could be considered state property.
An example of this ambiguity is evident in data for the 252 ( 14% of total preventable)
incidents with a general location of “ State Yard or Property” and a specific location of
“ Off Street or Hwy in R/ W,” where R/ W means “ right- of- way.” There is no way to know
whether these incidents occurred off to the side of a conventional highway, city street, or
freeway.
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3.2.2 Additional Data Needs
The reporting forms should collect more information for input into SIMS. These
additional data categories include:
• Hire date for Caltrans employee involved in the incident. This information allows
time on the job to be calculated to determine if refresher training is necessary.
• Date employee started current job.
• Birth date for the employee to determine whether any trends could be age- related.
• Vehicle mileage to determine incidents per mile driven per vehicle.
• Complete crash costs.
As an early result of this project, work is now underway to make it possible to access
repair cost information through SIMS. This data will help determine which types of
vehicles and locations generate the greatest losses. Cost data should include both direct
and indirect costs. Direct costs include vehicle repair costs, medical costs for injured
Caltrans personnel, and third- party costs ( property damage and personal injury). Indirect
costs include vehicle down time, additional vehicles for use during repairs, crash
investigation time, SCIF service fees, and data entry.
At present, there is no automatic link in SIMS between motor vehicle and personal injury
files. Each motor vehicle incident is assigned an “ M” number, and each personal injury is
assigned a “ P” number. In order to establish a link, an operator is required to go through
all of the motor vehicle accident forms and observe which ones have the “ Caltrans
Employee Injured” box checked “ Yes,” then search the personal injury forms using the
vehicle driver’s name or ID number to look for a match. A more effective system would
list the employee’s “ P” number as part of the motor vehicle incident file and list the “ M”
number in the personal injury file.
Presently, in addition to the injury information that SIMS collects, the State
Compensation Insurance Fund ( SCIF), which serves as Caltrans’ claims administrator,
gathers extensive data on Caltrans employees’ workers’ compensation claims. Currently,
the SIMS and SCIF data are not linked. Combining the injury and claims data would
generate useful information, such as the specific types of injuries likely to result in
workers’ compensation claims, their costs, and the extent to which such claims were
successfully disputed. This information would provide a context for calculating the
potential return on investment gained through injury prevention activities targeted at
specific injuries and specific types of incidents ( such as backing).
Extensive information is currently available from SCIF in an electronic format, making
integration into SIMS feasible. SCIF records: ( 1) payment date; ( 2) payment code; ( 3)
claim number; ( 4) check number; ( 5) fiscal year injury occurred; ( 6) first and last name
and middle initial of payee ( injured worker); ( 7) breakdown of amounts paid for:
compensation, medical, miscellaneous, and total costs; and ( 8) program code. Other
information available from SCIF under the state master agreement could be used to
establish a departmental claims tracking system. For each claim, SCIF can furnish the
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name of the office administering the claim, the adjuster name and telephone number,
names of SCIF attorneys involved in the case, the WCAB case number from the Caltrans
Return to Work Unit, information on whether the claim has been litigated, name of the
applicant attorney, and whether liability in the case was accepted, delayed, or denied.
SCIF can also provide start and end dates for the claim as well as type of current benefits.
3.3 Suggested Improvements in Data Collection, Entry, Database
Access, and Accident Investigation Training
Supervisors should receive uniform training in investigating accidents and injuries and in
filling out forms. A uniform procedure for filing reports needs to be established,
including agency- wide deadlines for completion.
Data entry and database use training could be improved. Currently, SIMS data entry is
conducted by a range of personnel not necessarily trained for that job, including
temporary workers and light- duty employees. Additionally, district safety officers should
be trained to use the database management software, so that they can generate reports and
analysis of SIMS data on a district level. Currently, most district safety officers must
request such reports from Sacramento.
Currently, each Caltrans district regularly generates statistics that include year- to- date
accident and injury rates. Additionally, Caltrans headquarters produces reports that
include district accident summaries, individual incident and claims histories for both
personal and motor vehicle injuries, and Cal/ OSHA district injury logs and summaries.
To make this data more useful, analysis should take place at least twice yearly to
determine injury and incident rates and trends. Finally, the data need to be distributed in a
regular, systematic manner to all employees, from top- level to rank- and- file.
3.3.1 Data Collection Lessons from Other State Departments of
Transportation ( DOTs)
Other state DOTs use data collection methods that could serve as models for Caltrans to
strengthen its current system. Below are several examples:
Idaho Transportation Department
Each of the six districts of the Idaho Transportation Department ( ITD) has a designated
data entry employee and all data are entered into the safety database at least once a week.
The data are drawn from a wide array of sources including employee accident forms, tort
claim forms, and safety meeting records. Only the seven safety staff members, six district
business managers, and the employees who enter data in each district may log onto the
database. The ITD’s chief safety staff members generate comprehensive quarterly reports
from this database. The safety manager first issues these statistics to top management in
summary form and then distributes a full formal report with complete accident
descriptions to all forepersons and section supervisors. The quarterly reports are
discussed in detail during monthly safety committee meetings.
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New York State Department of Transportation
The New York State Department of Transportation ( NYSDOT) created a safety
campaign to reduce motor vehicle backing accidents after annual trend reports generated
from the accident and injury database revealed that crashes of this type were increasing.
As part of the new safety campaign, NYSDOT created driving maps for the maintenance
yards and instituted routine reviews and updates of backing policies listed in the
employee manual.
Texas Department of Transportation
At the Texas Department of Transportation ( TxDOT), as soon as an incident occurs,
district staff sends an e- mail message to the central safety office, the Division of
Occupational Safety, which triggers the creation of an entry in their database. The
database, established 1989, is maintained by trained staff and tracks workplace injuries
and workers’ compensation claims on a daily basis, compiling data from a wide variety
of sources. For example, the finance division provides the employee’s hours worked
while the fleet equipment operations office submits information about the vehicle,
including its mileage.
Recently, after analyzing department injury data and concluding that backing was a major
source of injuries, TxDOT installed detectors, cameras, and back- up alarms in some
vehicles in several “ pilot” districts. An analysis of the data shows that backing incidents
have been reduced from an average of 100- 130 per year to 80.
Washington Department of Transportation
The Washington Department of Transportation ( WSDOT) established an internal injury
database in 2005 when its new chief safety officer was hired. Regional safety officers
input injury, lost time, and medical data. The database is capable of generating analyses
and reports from a number of different perspectives, depending on the information
needed by the safety officers. WSDOT provides managers with breakdowns of claim
costs and information regarding open cases within their individual regions on a regular
basis.
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4 Caltrans Policies and Procedures
4.1 Caltrans Manuals
Caltrans guidelines for backing maneuvers of department vehicles are contained in both
the Department’s Safety Manual ( Section 17.13) and the Maintenance Manual ( Section
8.36) ( Appendix D). A review of these two manuals as well as interviews with other state
DOTs indicate that Caltrans policies and procedures cover the topic of backing well. If
these policies and procedures were closely followed, backing incidents could be greatly
reduced.
The Caltrans Safety Manual states: “ The department recognizes that there is an increased
risk of vehicle accidents during vehicular backing maneuvers.” To decrease the
likelihood of a backing accident, the manual instructs that whenever feasible operations
will be modified to eliminate backing. Additionally, all sides of the vehicle are to be
visually inspected to assure there are no obstacles, and when two or more employees
work together, one employee shall act as a spotter at the rear of the vehicle.
Suggested modifications to the Safety Manual’s backing procedures are:
• Any time a vehicle is backed, if another Caltrans employee is present, that person will
act as a spotter.
• If a vehicle has been stopped or parked for any length of time, the driver shall exit the
vehicle and perform a visual inspection.
• In all procedures, the word “ shall” will be used rather than “ should.”
In the Maintenance Manual, backing policies and procedures are divided into three
sections: ( 1) Prior to Job/ Planning the Work; ( 2) Safety at the Worksite; and ( 3) Personal
Responsibilities.
In the first section, Prior to Job/ Planning the Work, supervisors are advised to plan work
projects to minimize the need for backing. At the tailgate safety meeting held prior to the
job, they are told to discuss how and when drivers are to conduct backing maneuvers
within the work zone, and to establish specific measures that will be taken to prevent an
accident.
In the second section, Safety at the Worksite, the emphasis is on workers who are on foot
in the work zone. Procedures include staying clear of moving vehicles, making sure that
employees never move equipment without first making positive visual contact with any
workers on foot around or near the equipment, and using a spotter.
The third part, Personal Responsibilities, requires that employees operating vehicles and
equipment be familiar with the blind spots for the specific equipment they are operating.
Workers and equipment operators must be trained in appropriate communication methods
for situations in which workers on foot are required to be in the same area as equipment.
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In addition, drivers should conduct a walk- around inspection of the vehicle before
entering.
A suggested modification for the Maintenance Manual is that in all procedures, the word
“ shall” be used rather than “ should” in order to emphasize that the procedure is
mandatory.
4.2 Spotters’ Guide
Based on information in the Safety and Maintenance manuals, a review of other state
DOTs’ procedures, and interviews with Caltrans safety personnel, the Traffic Safety
Center has designed a spotters’ guide that could be printed and distributed at tailgate
meetings. The guide includes general rules, driver responsibilities, spotter
responsibilities, and uniform hand signals for spotters. It is shown in Appendix E.
4.3 Accountability, Discipline, and Work Rules
A review of best practices for preventing workplace incidents and injuries revealed that
an essential component of any safety program is the establishment of a strong safety
culture, a key element of which is establishing a system of accountability at all levels of
the organization.
Such a system institutes safety goals and measures safety activities, with all employees
playing by the same rules and being held accountable for fulfilling their responsibilities.
The system also provides a means for helping employees to understand how their
individual performance contributes to maintaining workplace safety and teaching
employees to take personal responsibility for their own performance.
“ Accountability ranks right at the top with management commitment as a critical
ingredient in a company's safety and health management system. In fact, if
employees don't believe they're going to be held accountable ( experience
consequences) for the decisions they make related to safety, you can be sure that
any safety effort is ultimately doomed to failure” ( Oregon OSHA).
According to the United States Department of Labor OSHA recommendations, an
effective accountability system should include the following five elements:
1. Established standards in the form of company policies, procedures or rules that
clearly convey standards of performance in safety and health to employees. Before
individuals can be held accountable, they must be told what is expected.
Performance objectives must be attainable, clearly stated, realistic, challenging, and
measurable.
2. Resources needed to meet the standards, such as a safe and healthful workplace,
effective training, and adequate oversight of work operations.
3. A measurement system which specifies acceptable performance. It's important that
behaviors, rather than results, be evaluated. What action, or inaction, led to the
incident?
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4. Consequences, both positive and negative. Without an expectation of effective
consequences, accountability is not believable and has no credibility.
5. Application at all levels means that consequences are consistently applied
throughout the organization— top to bottom and across functions.
U. S. Occupational Safety and Health Review Commission ( OSHRC) decisions have
long demonstrated a core belief that safe work practices are not effective if their use is
not enforced. Typically the employer is held responsible if the organization does not
enforce its own rules. “[ A] n employer must make a diligent effort to discourage, by
discipline if necessary, violations of safety rules by employees."( OSHRC 1980). To
prove adequate enforcement of its safety rules, an employer must present evidence of
having a disciplinary program that was effectively administered when work rule
violations occurred. ( OSHRC 1996)
In its review of Secretary of Labor v. American Sterilizer Company ( 1997), the OSHRC
stated that if a company wishes to defend itself by claiming unpreventable employee
misconduct, the “ employer is required to prove: ( 1) that it has established work rules
designed to prevent the violation, ( 2) that it has adequately communicated these rules to
its employees, ( 3) that it has taken steps to discover violations, and ( 4) that it has
effectively enforced the rules when violations are discovered.” Further, “ It is not enough
that an employer has developed an exemplary safety program on paper. Rather, the
proper focus in employee misconduct cases is on the effectiveness of the employer’s
implementation of its safety program... Effective program implementation requires a
diligent effort to discover and discourage violations of safety rules by employees.”
In 1984, the “ Caltrans Guide To Employee Conduct and Discipline” 1 was issued to offer
“ supervisors a constructive approach for handling situations related to employee
discipline...[ The guide is to serve] as a general reference and will have served its purpose
if it brings about a better understanding of discipline as a positive factor in personnel
management.”
In March of 1985, in a section titled “ Offenses and Corresponding Adverse Actions,” a
disciplinary matrix was added that more specifically defined offenses and matched
offenses with suggested adverse actions. By 1992, the matrix included a section that
specifically addressed backing incidents.
1 Three versions of the disciplinary guide were available for this paper: March 1985, July 1992, and April 1998. There
may have been other versions that were issued between the original issue date of December 1984 and the April 1998
version.
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In 1994, the Department of Personnel Administration ( DPA) issued the " Supervisor's
Handbook, A Guide to Employee Conduct and Discipline," which was intended for use
as a general guide to State law only and was not designed to supplant individual state
departments’ policies. Nevertheless, Caltrans issued a revised guide in April 1998 that
was more in line with the DPA guide, having dropped the offense/ adverse action matrix.
With no further revisions or changes to the Caltrans guide since 1998, and based on
conversations with Caltrans safety personnel, it appears that the DPA guide has become
the de facto Caltrans guide to employee conduct and discipline
In 2008, the DPA’s Supervisors Guide, which had been revised in 2004, was pulled from
the DPA website because it no longer reflected current law and because it “ was not
DPA’s responsibility to maintain such a guide.” 2 This has the effect of leaving Caltrans
without a current conduct and discipline guide.
Two State of California agencies that still use an employee discipline matrix are the
Department of Corrections and Rehabilitation ( CDCR) and the Department of Forestry
and Fire Protection ( CDF). At the CDF, the minimum action for a first backing incident
is a five percent reduction in pay for three months.
Ideally, there would be studies that investigate the effects of a change in enforcement of
progressive discipline for preventable motor vehicle crashes carried out by a state
department of transportation. By comparing the long- term difference in crash rates for the
before and after periods, we would have proof of the efficacy of such a change in
enforcement. Unfortunately, such research has not been conducted.
There is, however, a large body of work demonstrating the efficacy of enforcement in
deterring unsafe behaviors, especially in the area of traffic safety. The objective of
increased safety enforcement is not to see how many employees can be disciplined, but
rather to try to reach the point where no one needs to be. By the time a driver receives
disciplinary action, the costs to Caltrans have already been incurred. No one knows how
severe the next motor vehicle incident will be. The same type of crash that causes no
injury today may take someone’s life tomorrow. The only way to eliminate injury and
fatal crashes is to eliminate all crashes.
Interviews with safety personnel at Caltrans and at other state DOTs strongly suggest that
by implementing tougher enforcement policies and by emphasizing safety and
accountability at tailgate and staff meetings, Caltrans has the opportunity to achieve
2 DPA Chief Counsel, interviewed 6/ 08
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significant improvements in workplace safety. Based on these interviews as well as a
review of the literature, the following actions are recommended:
• The consequences for preventable incidents should be made severe enough that
people will want to avoid them.
• The minimum action for a first preventable backing incident should be a formal letter
of warning.
• There should be no discretion regarding the minimum action
• Any supervisors who fail to follow Caltrans policy regarding applying minimum
disciplinary actions for safety violations will, themselves, be reprimanded.
These rules must apply to everyone, regardless of job classification, or previous
performance, and all employees must be made aware that this is the case. Mandatory
disciplinary action, with an established minimum level ( e. g., formal letter of warning), is
the only way to ensure uniformity of application. Even the most well- intentioned
supervisor is likely to favor certain workers or groups, and as soon as this happens the
system breaks down. Lack of discretion has the added benefit of removing pressure from
supervisors because they can no longer be asked by at- fault drivers to overlook the
violation since they do not have the ability to do so.
If the backing incident is merely the latest in a string of violations, or if the driver’s
behavior was particularly egregious, there is no reason that stronger action cannot be
taken. However, there must be no discretion at the minimal level, even in regards to an
employee who has an excellent record; the mandatory disciplinary action be applied.
4.4 Zero Incidents
There is a growing consensus that the only appropriate goal for safety in the workplace is
zero incidents. If we maintain that incidents and injuries are preventable, how can any
other number be acceptable? Unlike private industry, where the costs of injuries and
motor vehicle incidents ( MVIs) directly affect operating budgets as well as company
profits, at Caltrans the monetary costs of MVIs are neither felt nor seen by most
managers. This is not to say that managers are indifferent to worker injuries: quite the
opposite is true. It is simply that the associated costs are not readily apparent.
Given the financial structure of Caltrans and other government agencies, it is necessary to
implement a strategy that does not depend on financial accounting changes. The
establishment of a strong safety culture, a key element of which is a system that holds
drivers and supervisors accountable for preventable motor vehicle incidents, has the
potential to greatly reduce, if not eliminate, occupational incidents.
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Safety is considered a core value of the organization ( Oklahoma DOL). Establishing a
strong safety culture at Caltrans requires management commitment and employee
involvement. This would include insuring that:
• Safety is ingrained into every aspect of its operations.
• Employees understand their right to a safe workplace.
• Each person in the organization accepts responsibility for ensuring his/ her own health
and safety.
• Each person in the organization believes that he/ she has a duty to protect the safety
and health of their co- workers.
• All employees, regardless of job or position, are held to the same standards.
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5 Other Approaches for Possible Incorporation
Merit rating policies, which include both an “ experience rating” and a “ schedule rating,”
are worth exploring. An “ experience rating,” which retrospectively compares a firm’s
ratio of losses to all comparable employers ( in terms of business classification and size)
in the state, can be used to give employers and employees incentives to reduce the cost of
claims that might be excessive relative to other firms. A “ schedule rating” rewards
intentional behavior to reduce hazards, and works prospectively.
Regional analysis of claims might lead to Caltrans to “ price” workers’ compensation
coverage differentially for different districts or regions, or provide other region- specific
benefits based on differences in true workers’ compensation costs. But when considering
this approach, it is critical to avoid encouraging the organization to focus on how to
reduce claims at the expense of seeking ways to prevent injuries.
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6 Technology Solutions
6.1 Findings of the Literature Review
According to the TSC’s review of the literature, the most effective backing accident
prevention systems integrate multiple technologies including video, radar, and back- up
alarms, in addition to traditional devices adapted to the special requirements of the
backing maneuver. The following are highlights of the findings. For the complete review,
please see Appendix I.
A report on highway work zones suggested the following solutions might effectively
reduce backing accidents:
• Parabolic mirrors on construction equipment.
• Vibrating alarms that give notice of approaching vehicles.
• Sensing devices that sound an alarm when an object is near the vehicle.
• Closed- circuit television cameras, mirrors, and devices that stop a vehicle nearing a
collision ( Pratt et al. 2001).
A National Institute of Occupational Safety and Health ( NIOSH) investigation of backing
prevention equipment on job sites found that radar- video systems were successful at
alerting drivers to danger and directing their attention to a monitor ( Schneider 2008).
NIOSH- commissioned studies of radar- and sensor- based collision- warning systems for
construction equipment, heavy equipment, and off- road dump trucks found that:
• Camera and sensor systems are more reliable under warmer conditions and
experience difficulties under cold, snowy conditions ( Ruff 2005).
• Sensor systems do not perform well in congested work areas ( Ruff 2002).
• The tendency to produce false alarms suggest that sensor- based systems for proximity
warning should be used in combination with devices such as cameras, to allow the
operator to check the alarm source ( Ruff 2005).
• Radar systems installed in large, off- road dump trucks reliably detected small
vehicles, people, and other equipment ( Ruff 2004).
Mirrors are not the most effective means of increasing truck drivers’ visual range.
However, truck drivers believe supplemental mirrors have the potential to significantly
reduce blind- side and backing crashes ( Zeyher 2007).
Back- up warnings that alerted drivers that they were approaching known obstacles were
more successful in preventing incidents than warnings that sounded in response to a
surprise event ( Ayers et al. 2002). Some argue that audible alarms do not always protect
pedestrians, due to malfunctions and work site noise ( Zeyher 2007).
An analysis of backing collision data found that older drivers were over- represented in
backing crashes. Minivans and SUVs were also over- represented in backing crashes. The
authors suggested that older drivers might benefit from warning systems that
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incorporated higher- transmittance windows, higher- intensity backup lamps, and rearward
detection and warning devices. ( Ayers et al. 2002).
Durability and reaction time studies showed that radar and sonar systems generally
perform reliably, except under the following conditions:
• Cold and snow ( Ruff 2005).
• Congested work areas ( especially affects sonar systems) ( Ruff 2002).
• Cluttered conditions, when objects that pose no immediate danger set off false alarms
( Ruff 2005).
• When vehicles’ speeds exceed that at which most pedestrian collisions occur ( this
especially affects sonar) ( Glazduri 2005).
A study of particular relevance is the Arizona Department of Transportation ( ADOT)
evaluation of ETON brand Backspotter rear cameras on ADOT’s heavy vehicles. These
cameras were well received by field crews on dump trucks and stripers, but did not work
with trailers and medium trucks ( Owen 2006).
Recent innovations have made cameras less costly, smaller, and easier to operate under a
wide variety of conditions. These developments suggest that cameras may become one of
the most popular and affordable approaches to reducing work zone backing incidents
( Madison 2004).
A 1992 National Highway Traffic Safety Administration ( NHTSA) study found that
video systems performed well under good lighting conditions. Auxiliary mirror systems
covered a limited area and displayed distorted images. Sensor- based systems were
generally poor at detecting pedestrians behind the vehicle ( Mazzae and Garrott 1992).
In 1993, Tijerina et al. looked at Intelligent Vehicle Highway Systems ( IVHS)— separate
sonar, radar, or wireless units that comprise a flexible system that can respond to traffic
congestion. Their assessments showed that the majority of backing incidents occur
because drivers do not see or check for a vehicle, object, or pedestrian. The suggested
countermeasure was a rear- zone detection system.
In 1996, Eberhard et al. assessed electronics- based collision avoidance systems for
drivers of passenger vehicles, focusing on testing of sensor performance and driver
interface quality. Findings suggested that while none of the systems had an “ ideal”
interface, most were ergonomically acceptable and aided in preventing backing
collisions.
An analysis conducted by Lerner, et al. in 1997 brought together data from three studies
that sought to determine the potential effectiveness of visual warnings. The analysis
concluded that because drivers glance in many locations, it is difficult to place a display
where it will be reliably conspicuous. Therefore, the authors suggested, visual warnings
should supplement, not replace, acoustic warnings.
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A 2005 study reports that CMOS ( complimentary metal- oxide semiconductor) and CCD
( Charged Couple Device) image sensor cameras, FMCW ( Frequency Modulated
Continuous Wave) radar, and lidars ( light- detection and ranging devices) are the most
frequently used sensors. To overcome problems in pedestrian detection, thermopile and
infrared sensors were applied to intelligent vehicle systems; but this solution is costly.
The report also suggested that protocols should be developed to enable products from
different manufacturers to communicate with each other ( Li et al. 2005).
6.2 Rear Radar Detection Devices Currently Installed in Caltrans
Vehicles
Between 2003 and 2006, Caltrans installed rear radar detection systems designed to alert
vehicle operators to obstacles in fifteen vehicles. The equipment IDs, vehicle
descriptions, and installation dates are shown in Appendix F. At the time of this report,
all but one of the devices were still installed.
The systems operate in a pre- defined coverage area and report the distance of the closest
object via visual range indicators and an audible signal to a vehicle operator. The in- cab
display is shown in Figure 12.
Figure 12: The Preco PreView ™ Display
In order to assess equipment operator experience with and reaction to the radar devices, a
questionnaire ( Appendix G) was sent out to the supervisors overseeing these operators.
At the time of this report, ten questionnaires had been returned, almost all of which
registered positive responses to the device. Before Caltrans proceeds to procure
additional back- up safety systems, Field Operational Tests ( FOTs) could be used to
determine how certain models perform under ordinary working conditions. A sample
FOT design is shown in Appendix H.
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7 Conclusions
Two potentially powerful tools for eliminating incidents and injuries emerged from our
research: enhancement of the Safety Information Management System ( SIMS) database
to allow a clearer understanding of the scope and magnitude of the problem, and
management action to instill and support a strong culture of safety throughout the
organization.
The current SIMS system can be improved by closer supervision of data gathering and
input and by adding additional data fields. Our review found many examples of
incomplete or incorrect information. We also found that some of the fields are confusing
or subject to different interpretations.
Authority to enter data into SIMS should be limited to employees who have received
specific training so that information contained in the incident report may be checked for
accuracy and completeness as the data is entered. Training district safety officers to
generate different reports will enhance Caltrans’ understanding of incident and injury
trends. Additionally, SIMS can be made more powerful with the addition of SCIF claims
data, driver background information, and data from the Caltrans Division of Equipment.
This would allow for in- depth analyses which help determine which types of injury incur
the most workers’ compensation claims and the highest costs, what equipment and
locations have high incident rates, and which employee cohorts might benefit from
refresher training. This analysis would also provide a context for calculating the return on
investment gained through prevention activities. As an early result of this project, work is
currently underway to make it possible to access repair cost information through SIMS.
At the present time, there are no consistently followed policies for dealing with
employees who are involved in preventable motor vehicle incidents. Best practices
suggest that a highly effective safety tool is the establishment of a strong safety culture, a
key element of which is a clear system of accountability. Caltrans’ Safety and
Maintenance manuals provide detailed guidelines for safely backing a department
vehicle. However, a series of changes in policy at a statewide level have left Caltrans
without a current conduct and discipline guide. Because the vast majority of backing
crashes are caused by failure on the part of the driver to follow backing guidelines,
enforcing adherence will enhance safety and reduce costs. Policies in place at other state
Departments of Transportation ( DOTs) present discipline ideas that can be used at
Caltrans.
Caltrans has installed fifteen rear radar detection systems. Until recently, when an
equipment operator questionnaire was sent out, there has been little in the way of
feedback regarding the usefulness of the devices. Before Caltrans proceeds to procure
additional back- up safety systems, Field Operational Tests ( FOTs) could be used to
determine how certain models perform under ordinary working conditions. We offer an
outline of a FOT in Appendix G.
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8 References
Ayers, T., Trachtman, D., and Young, D. ( 2002), “ Passenger- side Rear- view Mirrors:
Driver Behavior and Safety,” International Journal of Industrial Ergonomics,
October 2004.
Eberhard, C. D., Moffa, P. J., Young, S. K., and Allen, R. W. ( 1996) Development of
Performance Specifications for Collision Avoidance Systems for Lane Change,
Merging and Backing. Task 4 Interim Report: Development of Preliminary
Performance Specifications. TRW Space and Electronics Group and National
Highway Traffic Safety Administration.
Glazduri, V. ( 2005) An Investigation Of The Potential Safety Benefits Of Vehicle
Backup Proximity Sensors. Transport Canada, Paper Number 05- 0408.
Harpster, J. L., Huey, R. W., Lerner, N. D. and Steinberg, G. V. ( 1996), Backup Warning
Signals: Driver Perception and Response, DOT Technical Report DOT HS 808 536
Kim, S. Oh, S., Kang, J., Ryu, Y., Kim, K., and Park, S. ( 2005). Front and Rear Vehicle
Detection and Tracking in The Day and Night Times Using Vision and Sonar Sensor
Fusion. Intelligent Robots and Systems, 2005.
Kim, Y. ( 2002). Effects of Driver, Vehicle, and Environment Characteristics on Collision
Warning System Design. Avdelning Institution.
Lerner, Neil, Harpster, Jeffrey, Huey, Richard, Steinberg, Geoffrey ( 1997), Driver
Backing- Behavior Research: Implications for Backup Warning Devices,
Transportation Research Record 1573n Transportation Research Board, Washington,
DC.
Li, L., Jingyan S., Fei- Yue W., Wolfgang N., and Nan- Ning Z. ( 2005), “ IVS 05: New
Developments and Research Trends for Intelligent Vehicles,” IEEE Intelligent
Systems, Vol. 20, no. 4, pp. 10- 14.
Madison, A. ( 2004) Opting Out of Blind Spots. Construction Trucks.
Mazzae, E. N. and Garrott, W. R. ( 1992). Evaluation Of The Performance Of Available
Back- over Prevention Technologies For Light Vehicles. Paper 07- 0292. National
Highway Traffic Safety Administration.
Moffa, P., Austin, J., Dow, G. S., Sizyan, I., and Hibben, M. ( 1996). Development Of
Performance Specifications for Collision Avoidance Systems for Lane Change,
Merging, and Backing. Task 5 Interim Report: Crash Countermeasure Technology
Investigation. TRW Space and Electronics Group and National Highway Traffic
Safety Administration.
National Highway Traffic- Safety Administration ( 2006), Vehicle Back- over Avoidance
Technology Study: Report to Congress ( 2006). .
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Oregon OSHA Online Course 100, Safety and Health Management Basics, MODULE
TWO: ACCOUNTABILITY,
http:// www. orosha. org/ educate/ training/ pages/ 100xm2. html, Accessed 9/ 7/ 08
OSHRC 1980, Wallace Roofing Company, OSHRC Docket No. 76- 4844
OSHRC 1996, Gem Industrial, INC.: OSHRC Docket No. 93- 1122
OSHRC 1997, American Sterilizer Company , OSHRC Docket No. 91- 2494
Owen, S. R. ( 2006). ADOT - ATRC Vehicle Research- Radar Warning Systems: 2005- 06.
Summary Report AZ- 473 ( 7). Arizona Department of Transportation.
Pratt, S. G., Fosbroke, D. E., and Marsh, S. M. ( 2001). Building Safer Highway Work
Zones: Measures to Prevent Worker Injuries From Vehicles and Equipment.
Department of Health and Human Services.
Ruff, T. ( 2002). Recommendations for Testing Radar- Based Collision Warning Systems
on Heavy Equipment. National Institute for Occupational Safety and Health,
Spokane Research Laboratory.
Ruff, T. ( 2005). Evaluation of a Radar- Based Proximity Warning System for Off-
Highway Dump Trucks. National Institute for Occupational Safety and Health,
Spokane Research Laboratory.
Schneider, Scott ( 2008). “ An Ounce of Prevention Preventing Backovers of Road
Construction Workers,” Transportation Builder, May/ June 2008.
Tijerina, L., Hendricks, D., Pierowicz, J., Everson, J., and Kiger, S. ( 1993). Examination
of Backing Crashes and Potential IVHS Countermeasures. National Highway
Traffic- Safety Administration Final Report.
U. S. Bureau of Mines. Avoiding Backing Accidents ( 1991). Highway and Heavy
Construction.
Zeyher, A. ( 2007). " Separation Is A Positive” Roads and Bridges, September 2007: Vol
45, No 9.
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9 Appendices
Appendix A: Accident Identification Card Form STD. 269
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Appendix B: Vehicle Accident Report Form STD. 270
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Appendix C: Data Input for Motor Vehicle Accident Form PM- S- 0270
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Appendix D: Backing Sections of Caltrans Safety and Maintenance
Manuals
Caltrans Safety Manual, Chapter 17 Motor Vehicle Safety
17.13 Vehicle Backing Policy
The Department recognizes that there is an increased risk of vehicle accidents during
vehicular backing maneuvers. To decrease the likelihood of a backing accident, the
following procedures shall be adhered to:
• Whenever feasible, operations will be modified to eliminate backing. If backing is
necessary, the affected supervisor, operator and employees will discuss the backing
maneuvers before beginning operations.
• Before backing any vehicle, the operator shall visually inspect all sides of the vehicle
to assure there are no obstacles, clearances or employees in the area. It may be
necessary for the operator to exit and walk around the vehicle to perform a visual
inspection.
• The driver should be alert to any other pedestrian or vehicular traffic that may enter
the backing zone. If pedestrian traffic is anticipated, a spotter shall be utilized
whenever practicable while backing.
• When two or more employees work together, the driver shall ask the other employee
to act as a spotter at the rear of the vehicle before starting the backing movement. The
operator and spotter shall have a clear understanding of the backing maneuver before
moving the vehicle.
• If the operator must stop or park the vehicle in a position that will require backing,
the vehicle should be positioned to maximize visibility to the rear and critical areas
adjacent to the vehicle.
Caltrans Maintenance Manual, Chapter 8: Protection Of Workers
8.13 Planning Work To Reduce Worker Exposure
Supervisors shall plan all work methods to minimize the need for the backing of
equipment and vehicles at the work site.
8.36 Backing of Vehicles and Equipment
Backing accidents have always been the most prevalent type of vehicle accident. Because
so many of the tasks Maintenance employees perform involve the backing of vehicles
and equipment, the potential for serious accidents exists, and extra emphasis must be
placed on preventing their occurrence.
Prior to Job/ Planning the Work:
1. Supervisors should plan work projects to minimize the need for backing of vehicles
and equipment whenever possible. For example, the forward mode of cone retrieval
should be utilized for retrieving lane closures.
2. Design the work space to eliminate or decrease backing and blind spots; when
feasible pull trucks into the work zone and let the operation catch up to them.
3. At tailgate safety meetings, prior to the job, discuss how and when vehicles will be backing
within the work zone and specific measures that will be taken to prevent an accident.
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Safety at the Worksite:
1. Workers on foot will be separate from equipment as much as possible: ensure that
employees on foot stay out of the work area and in clear view of those who are
operating equipment.
2. Minimize the distance heavy equipment needs to back up in order to gain access to
the work area.
3. Employees should never move equipment without making positive visual contact
with any workers on foot around or near the equipment.
4. In work zones where moving equipment has the potential to strike a worker on foot,
employees shall not place themselves in or near the path of backing vehicles and
should not enter the work area until it is clear for hand work. One person should be
designated as a lookout while vehicles/ equipment are moving within the work area.
5. Every backing situation is new and different. Even if you work at the same location
several times a day, you should be watchful for changes and any new obstacles.
6. Use a spotter. The driver and spotter should use hand signals instead of verbal ones
and make sure they understand each other’s signals. Don’t have the spotter walking
backwards while giving instructions.
7. During shoulder or pavement rolling operations, make sure all workers on foot are
clear of the work area before moving any vehicles/ equipment.
Personal Responsibilities
1. Employees operating vehicles and equipment must be familiar with the blind spots for
the particular equipment they are operating. Remember that mirrors can never give
the whole picture while backing.
2. Train workers on foot and equipment operators in appropriate communication
methods ( e. g., using hand signals and maintaining visual contact) to be used when
workers on foot are required to be in the same area as equipment.
3. Do a walk- around of your vehicle before entering. Check for obstructions, low-hanging
trees and wires, and any other potential clearance- related problems.
4. On- foot personnel need to make sure they are a safe distance from vehicles in the
work area. Do not stand where the operator cannot see you; a vehicle that has the
potential to back up could run you over.
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Appendix E: Backing and Spotters Guide
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Appendix F: Caltrans Vehicles Installed with Preco Rear Radar
Systems
Eq. ID Description
Installation
Date
0088952 UTILITY BODY CREW CAB 3/ 2/ 2006
0334142 DUMP BODY W/ LOADER TILT CAB 3/ 24/ 2006
7001826 PICKUP SUPER 1/ 2TON EXTCAB AFV 2/ 1/ 2006
7000565 LOADER FRONT END 2- 1/ 2 C. Y. 11/ 1/ 2006
0137274 CONE BODY 3/ 30/ 2006
0237039 CARGO BODY W/ HOIST12FT DIESEL 11/ 1/ 2006
7002018 SWEEPER CONV. 3- 4 CY DIESEL 10/ 1/ 2005
0538490 CATCH BASIN & SEWER LINE CLEAN 11/ 1/ 2005
0537535 CATCH BASIN & SEWER LINE CLEAN 11/ 9/ 2005
0538808 BRIDGE REPAIR 6/ 15/ 2006
0537534 CATCH BASIN & SEWER LINE CLEAN 5/ 20/ 2003
0537174 CATCH BASIN & SEWER LINE CLEAN 2/ 6/ 2006
0538301 CATCH BASIN & SEWER LINE CLEAN 2/ 1/ 2006
3636911 GRADER- 6 WHL DR W/ PLOW 150 5/ 20/ 2003
0538302 CATCH BASIN & SEWER LINE CLEAN 2/ 1/ 2006
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Appendix G: Equipment Review Questionnaire for Caltrans Equipment
Operators
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Appendix H: Field Operational Test Scope and Requirements
Before any large- scale investment of resources is made in warning devices, it must be
determined whether the expected benefits ( both monetary and social) outweigh the
expected costs. One way to test this is through a field operational test ( FOT).
The FOT of any backing warning device should be conducted on vehicles used in normal
service at the normal location of the vehicle. Overall, this project should take place over a
period of 26 months. The formal FOT will be conducted over a 25- month period
composed of one month of training/ acclimatization and 24 months of use/ observation.
This will be preceded by a one- month period during which the warning device will be
installed and tested.
The purpose of the pilot test is to collect information on device effectiveness as well as
driver comments and suggestions. It will focus on:
• Reliability and quality of warning information.
• Driver reaction to the warning device.
• Equipment reliability.
• Changes in the number of incidents ( this will be highly dependent on the number of
units installed).
An advisory board should be formed and meet four times during the project; at the
beginning, after installation and training, at the end of the first operational year, and at the
end of the second operational year.
Data analysis will be conducted both during and after the field tests. The analysis will use
before- and- after design.
EVALUATION GOALS
The following three broad evaluation goals ( benefits, acceptance and human factors,
performance) will be used for this system evaluation.
Goal 1: Achieve an in- depth understanding of the benefits of the rear radar/ video
warning system. This goal can be subdivided into a number of different categories, two
of which, safety, and productivity, will be used here.
Goal 1 A: Achieve an In- Depth Understanding of Safety Benefits. The primary safety
benefit expected from the deployment of the warning devices is a reduction in the number
and/ or severity of backing incidents. Because such incidents are relatively rare events, a
statistically significant reduction during the FOT is unlikely unless a relatively large
number of devices are installed. If this does not occur, surrogates, such as observed
behavior and driver reported incidents avoided, will have to be used.
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Goal 1 B: Achieve and In- Depth Understanding of Productivity Benefits. Deployment of
the warning devices can result in productivity increases through cost savings from
reduced numbers and/ or severity of crashes, reduced workers comp costs, and reduced
third- party costs. Any cost savings resulting from productivity gains would have to take
into account the cost increases associated with the purchase and maintenance of the
systems, training costs for drivers and mechanics, and possibly operating costs.
Goal 2: Assess User Acceptance and Human Factors. Interviews and surveys will be
used to determine drivers’ perceptions of the value of the device.
Goal 3: Assess Performance and Capability Potential. This goal addresses the ability of
the system to perform its specified functions while meeting reliability and maintenance
requirements. Performance will be measured using incidents and driver feedback, while
assessment of system reliability will be based on the need for servicing during the FOT.
EVALUATION DATA SOURCES
In order to conduct the evaluation of the back- up warning devices, data will be collected
from the following sources:
Historical and FOT Crash/ Incident Data. Historical data will be from the Caltrans
SIMS database. Annual rates of crashes, injuries, and costs will be based on 10- year
averages from the database. This information will be examined in a four- step process to
identify problem areas as follows:
• Separate data by crash type
• Identify the predominant critical events and critical reason that led to the vehicle’s
involvement in the crash for the crash type of interest
• Identify the movements prior to those critical events
• Use the combination of the critical events and the movements prior to define the
driving problem.
Surveys and Interviews. All personnel involved in the FOT, including drivers,
supervisors, mechanics, and managers will be asked to participate in at least one written
survey or personal interview, in order to understand how the backing devices affect their
job performance and working conditions. Those directly involved with the driving task
will be surveyed several times over the course of the FOT. Information from these
contacts will be the primary source for assessing user acceptance and human factors.
As the FOT progresses, drivers will be asked to comment on the usefulness of the system
and how it has affected their driving. The final interview, at the end of the FOT, will seek
in- depth attitudes and opinions regarding the system, the overall effect it had on their
driving, and what changes they would make in the system.
Supervisors will follow a pattern similar to the drivers. As the FOT progresses they will
be asked to comment on driver attitudes and system acceptance. As with the drivers, the
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final interview will seek in- depth attitudes and opinions regarding the system, the overall
effect they feel it had on the drivers, and what changes they would make.
Fleet Operations Records. System reliability, operating costs, and savings created
through use of the devices will be established by using Caltrans maintenance and
operational records.
Caltrans will provide its historic incident data as well as relevant maintenance records
and costs. This information will be used to estimate the costs and benefits of extending
installation to the entire fleet.
EVALUATION METHODS
In this section we will explain how the various data elements collected during the FOT
will be brought together to meet the goals established above.
Goal 1A: Safety Benefits
As previously discussed, the primary purpose of the warning devices is to prevent fatal,
injury, and property- only- crashes. Since Caltrans experiences an average of
approximately 250 backing incidents a year, distributed throughout the state, the only
way to potentially observe a change in the incident rate would be to:
• Install a large number of devices ( e. g., 100).
• Install all devices in a single district.
• Install all devices in a specific type of vehicle ( e. g., cone body or dump body) or, at
most, two vehicle types.
Goal 1B: Productivity Benefits
If installation of the warning devices can reduce the number or severity of crashes, reduce
injuries and fatalities as well as lower the level of what is considered “ normal” wear- and-tear,
cost savings will accrue to both Caltrans and the public. To the extent that output
remains unchanged or increases, the end result will be an increase in productivity. The
value of this gain will be used as an input to the benefit/ cost analysis.
Goal 2: User Acceptance and Human Factors
The objectives for this goal will focus on driver acceptance, perceptions of usefulness,
and product quality. If the warning device is viewed as obtrusive by drivers, a burden by
supervisors, or difficult to operate and maintain by maintenance, then deployment will be
difficult even if benefits could be shown. Information from surveys and interviews will
be the primary source for this goal. Some questions are designed to be asked several
times over the course of the FOT in order to gather longitudinal data representing the
change in opinions or perceptions over time.
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Goal 3: Performance and Functionality
Measures of the performance and functionality of the warning devices will be based on
driver feedback, incident reduction, and maintenance records.
BENEFIT- COST ANALYSIS ( BCA)
Even if an FOT meets all of its operational goals, the system must still be economically
feasible if it is to progress to large- scale implementation. A BCA carried out on public
sector projects involves more than measuring corporate net benefits. Social benefits and
costs, opportunity costs, and other, often intangible, impacts that may be difficult to value
also must be monetized and factored into the analysis. Ultimately, though, the final
question remains the same, are total benefits greater than total costs? If the answer is yes,
the project can be said to be economically feasible.
The framework of BCA involves:
• Identifying all the benefits and disbenefits of the project.
• Quantifying all benefits and disbenefits in dollars or some other unit of measure.
• Selecting an appropriate interest rate at which to discount benefits and costs to a
present value.
For the backing warning devices, the list of potential benefits include savings due to
reduced number and severity of crashes and the resulting gains in productivity. Costs
include initial startup costs and maintenance.
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Appendix I: Literature Review
Literature Review for Caltrans Backing Safety Report
Sarah Duffy, MPP
UC Berkeley Traffic Safety Center
December 2008
INTRODUCTION
The purpose of this literature review by the UC Berkeley Traffic Safety Center ( TSC) is
to help Caltrans assess possible technologies for use in the workplace to prevent backing
incidents that result in accidents and injuries, most of which are deemed preventable,
even in noisy work zones. Based on 10 years of SIMS data ( 1998- 2007), 93.2% of
backing incidents at Caltrans were determined to have been preventable by the driver,
indicating that this is an area of workplace safety that merits close scrutiny.
As of 2006, Caltrans had installed at least 15 radar devices in maintenance vehicles. This
chapter considers additional collision avoidance systems and driving enhancement
systems that Caltrans might consider implementing. These systems interact with the
driver by issuing alarms or by informing the driver of potential crash risks, including rear
obstructions ( 2). They can reduce the frequency and severity of crashes associated with
backing incidents ( 2). The more sophisticated versions of these devices use radar, sonar,
still cameras, video, and warning alarm systems.
Workers in construction zones can become desensitized to the presence of vehicles, often
because they work in close proximity to them in a loud environment. While visibility
garments and back- up alarms can improve work- zone safety, they don't go far enough if
the driver still cannot see what's behind him. The following example taken from a
Fatality Assessment Causation Assessment ( FACA) report attests to this fact: " A thirty-six-
year- old construction inspector died when an asphalt dump truck backed over him.
The decedent was wearing an orange reflective vest and hard hat at the time of the
incident. The dump truck's backup alarm was operational and functioning properly. The
driver of the truck stated that he never saw the decedent." ( 8)
TECHNOLOGY OVERVIEW
The primary use of technology in preventing backing collisions is to warn the driver and
others in the vehicle’s vicinity of a potential risk. This must be done in a manner that
allows sufficient time for preventative action: for the driver that is the equivalent of
reaction time plus stopping time ( 1). In this section we provide a review of studies that
compared different technologies ( e. g. radar versus camera). Later sections focus on
individual technology types.
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One of the earliest comprehensive studies of back- over prevention technologies was a
1992 National Highway Traffic Safety Administration ( NHTSA)- commissioned study of
11 commercially available back- over prevention technologies for light vehicles. Its
objective was to assess how well they detected objects at the rear of the vehicle. ( 22).
Video systems performed well in good lighting conditions ( 22). Auxiliary mirror systems
covered a limited area and displayed distorted images because of mirror convexity and
other factors ( 22). Sensor- based systems were generally poor at detecting pedestrians
located behind the vehicle ( 22). Since the publication of these results, considerable
additional investigation has been directed toward back- over prevention technology.
Another early report, published by Tijerina et al. in 1993, examined the potential of
Intelligent Vehicle Highway Systems ( IVHS). IVHS refers to separate sonar, radar, or
wireless units that comprise a flexible system that can respond to traffic congestion ( 33).
This report examined IVHS capabilities by modeling types of backing crashes and
pairing them with potential IVHS crash avoidance countermeasures. The assessments by
Tijerina et al. showed that approximately 87% of backing incidents occurred because
drivers did not see or check for a vehicle, object, or pedestrian; the suggested
countermeasure was a rear- zone detection system ( 31).
In their 1996 study, Eberhardt et al. assessed several electronics- based collision
avoidance systems for drivers of passenger vehicles in avoiding collisions ( 11). One
element of their research was an evaluation of how well collision avoidance systems
studied were designed from the point of view of human factors ( 11). They studied Side-
Looking Collision Avoidance Systems ( SCAS), which had detectors on the right and left
sides, and Rear- Looking Collision Avoidance Systems ( RCAS), which used video
cameras to enhance the driver’s ability to see objects to the rear ( 11). They focused their
testing the systems’ sensors performance and the quality of the systems’ driver interfaces.
Overall, while none of the Collision Avoidance Systems had an “ ideal” interface, most of
were ergonomically acceptable , and they aided in preventing backing collisions ( 11).
Eberhardt et al. were not the only researchers to find that CAS interfaces were less than
ideal. A 1997 analysis by Lerner, et al. brought together data from three prior studies that
sought to determine the potential effectiveness of visual warnings as a primary means of
alerting the backing driver and concluded that because drivers glance in many locations it
is difficult to place a display where it will be reliably conspicuous ( 1). Therefore, if visual
warnings are used, they should supplement, not replace, acoustic warnings ( 1). The sub-headings
below contain discussions of studies that examined specific acoustic and visual
backing technologies.
In terms of the most recent technological developments, a 2005 study reports that CMOS
( complimentary metal- oxide semiconductor) and CCD ( Charged Couple Device) image
sensor cameras, FMCW ( Frequency Modulated Continuous Wave) radar, and lidars
( light- detection and ranging devices) are the three most frequently used surround sensors
for environment sensing. However, conventional vision- based pedestrian detection is
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difficult to perfect because pedestrians usually wear clothes in different styles and colors
and might also carry items such as hats or bags of varied shapes ( 4) To conquer such
problems, researchers have applied thermopile and infrared sensors to intelligent vehicle
systems that can detect pedestrians passively without illuminating the environment ( 4).
The shortcoming with this solution is cost, so realizing reliable, low cost on- vehicle
thermopile or infrared sensors should be a current goal ( 4).
This report also suggest that inter- vehicle, vehicle- roadside, and vehicle- driver
information sharing is currently the most attractive trend in intelligent vehicle research
and that it will be important to set up communication protocols so that products from
different manufacturers can communicate with each other ( 4). We did not locate any
research indicating that technology manufactures have since decided to share
communication protocols.
In terms of qualitative feedback, in 2001 the U. S. Department of Health and Human
Services published a report on highway workforce zones based on information obtained
during a workshop attended by participants from government, labor, industry, academia,
and state departments of transportation ( 26). The participants suggested that the following
engineering solutions might effectively reduce accidents:
1) Parabolic mirrors on construction equipment
2) Individual vibrating alarms that can give workers 8- 10 seconds notice of approaching
vehicles
3) Sensing devices that sound an alarm when an object is near the vehicle
4) Closed- circuit television cameras, mirrors, and devices that stop a vehicle nearing a
collision
5) Transmitters worn by workers that signal approaching construction equipment
6) Tapes that sound an alarm when a person or vehicle crosses them ( 26)
This report addresses the first four of these six suggestions. We did not locate any
significant research or investigatory journalism addressing the latter two.
Lastly, in 2006 the National Highway Traffic Safety Administration issued a report to
Congress assessing vehicle back- over avoidance technology. Results of this study
showed that ultrasonic and radar backing aids did poorly in detecting child pedestrians
behind the vehicle ( 32). Rearview camera systems typically allowed drivers to see
pedestrians in the majority of the rear blind zones ( 32). It should be noted that this study
focused on passenger, rather than construction and maintenance, vehicles and did not
focus on work- zone safety. Because countermeasure effectiveness also depends on the
ability of drivers to use the technology, available human factors research was examined
( 32). Their analysis of driver behavior suggested that drivers who are not expecting
objects to be behind their vehicles will not stop soon enough to avoid striking them ( 32).
The researchers commented that additional human factor research is needed to estimate
the effectiveness of new systems ( 32).
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DRIVER AND VEHICLE CHARACTERISTICS AND BACKING
TECHNOLOGY
How driver and vehicle characteristics affect the likelihood of a backing collision merits
consideration in assessing the effectiveness of backing prevention technologies.
A 2002 report published by Kim et al. used quantitative and qualitative methods to test
the hypothesis that the capability of collision avoidance would not be same among
drivers, vehicles, and environment groups with different characteristics ( 18). Their
findings showed that heavy trucks had a higher susceptibility to fatal rear- end accidents
than cars and light trucks. They also found significant differences in Required Minimum
Warning Distance ( RMWD) among different vehicle types and braking systems, but only
small differences among age and gender groups, ( 18) suggesting that designers of
collision avoidance systems should focus on vehicles, rather than drivers.
A 2001 dynamic field experiment both confirms and undermines Kim et al.’ s findings.
Tests were conducted to examine how rear- window transmittance and back- up lamp
intensity affected drivers’ backing behavior ( 20). Results indicated that drivers did not
adjust their behavior to take into account variations in available light, at least under
conditions where they experienced little uncertainty regarding obstacles ( 20). Alongside
reviewing the results of the field experiment, researchers analyzed three years of crash
data from the General Estimates System ( GES) file for backing crashes. Variables of
interest in the GES data were driver age, ambient light condition, and the type of
passenger vehicle involved. The crash data indicated that older drivers were over-represented
in backing crashes. The crash data also indicated that minivans and sport
utility vehicles were over- represented in backing crashes. Based on the results of the field
experiment and GES data analysis, the authors suggested that older drivers might benefit
from warning systems that incorporated higher- transmittance windows, higher- intensity
backup lamps, and rearward detection and warning devices ( 20).
MIRRORS
Mirrors are important tools for eliminating some blind spots that cause truck driver
backing accidents. In the 1970s, the National Highway Traffic Safety Administration
made an abortive attempt to mandate the use of a very large West Coast mirror on the
right side of new trucks, but the idea was dismissed because the mirror obstructed
forward vision ( 15). Nonetheless truck drivers still find supplemental mirrors have the
potential to significantly reduce blind- side and backing crashes.
An analysis performed by Lerner et al. offers an important description of driver mirror
use in the course of normal backing in passenger cars. The research team found that there
was a great deal of variability in where drivers directed their glances while backing, with
glance location affected by the type of maneuver, the point during the maneuver,
individual differences, and vehicle characteristics ( 1). Older drivers showed more mirror
use and less over- the- shoulder looking than younger drivers, and the most frequent
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glance location was over the right shoulder. Only roughly 10% of the time were drivers
looking forward while backing ( 1). This research suggests that mirrors better serve as
supporting rather than primary backing prevention equipment.
Passenger- side rear- view mirrors ( PRMs) address restricted driver view and have been
standard equipment on motor vehicles sold in the US for many years, although they are
not required by the federal motor vehicle safety standards. Numerous studies have
documented the value of PRMs in providing rearview visual information. Very few
studies have proven, however, regarding the actual safety benefit of PRMs. A review of
the research literature and several initial studies ( driver observation and accident- data
analysis), suggest that PRMs may not be associated with any substantial accident
prevention, perhaps because they are not consistently used ( 20).
As it regards tucks, a driver’s direct field of view in a truck is significantly more
restricted than in other vehicle types. Trucks without a right fender mirror are
significantly over- involved in crashes ( 11). Observational data collected by reporter John
Bower indicated that only about 70 percent of trucks with conventional cabs have right
fender mounted mirrors, which can fill in the driver’s view along the front right side.
( 10). In 1995 Eberhard et al. published an analysis of crash data, measurements of fields
of view, and observational data on the variety and distribution of mirror configurations in
trucks, which suggested a need for improved driver vision to address specific truck crash
types including backing ( 11). The results illustrate a safety problem in the area where the
driver’s view is more restricted, but researchers do not recommend that mirrors are the
most effective means of increasing truck driver s’ visual fields.
BACK- UP ALARMS
Back- up alarms emit a noticeable sound when a vehicle nears an object in order to warn
pedestrians of moving vehicles. Reaction and stopping time algorithms are typically used
to inform back- up alarm onset times for warning systems.
Time to collision ( TTC), the amount of time for vehicle to contact a target object from its
current location, became the metric used in reference to back- up alarms after Lerner et al.
conducted a 1997 study of reaction and stopping times. It showed that TTC appeared to
be a useful basis for a warning algorithm ( 1). The distance at which drivers felt that a
warning would be appropriate was a function of backing speed, with longer distances
required for higher speeds ( 1). For the danger alarm, this change in distance was roughly
proportional to speed, so that the desired TTC was relatively constant across backing
speeds, although somewhat shorter at the highest speed ( 1). Given the observed backing
speeds and stopping distances, the reaction times of the drivers appear consistent with an
average TTC of approximately 2.0 seconds ( 1).
A number of factors complicate the implementation of an effective warning system,
including the fact that drivers who are parallel parking or backing to a wall or curb often
intentionally bring their vehicles into close proximity to objects. Because there is no way
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for the system to know the driver’s intentions, there is a high potential for nuisance
warnings, which, in terms of user acceptance, must be minimized while maintaining
adequate warning for truly unaware drivers ( 1). Warning systems must be effective over a
wide range of speeds and scenarios. Backing out of an angled parking space, backing
along an extended driveway, or parallel parking, require different speeds, glance
locations, reaction times, and stopping distances. An effective back- up warning system
needs to accommodate all of these scenarios ( 1).
Based on the results of a two- part study consisting of a field experiment and a laboratory
experiment, Harpster et al. suggested that it might be beneficial to have two distinct back-up
warnings: those for imminent crashes versus cautionary warnings ( 3).
An imminent crash avoidance situation is one in which the potential for a collision
requires an immediate vehicle control response that modifies a planned response ( 3). The
desired point for imminent crash warnings in terms of TTC was consistent across the
range of vehicle speeds, with a mean of 1.6 seconds ( 3). This suggests that TTC may be
an appropriate basis for warnings, one that is consistent with subjective judgments and
with the manner in which backing drivers actually perform ( 3).
A cautionary crash avoidance situation is one in which the potential for a collision
requires immediate attention from the driver, which may require a vehicle maneuver, but
does not meet the definition of an imminent crash avoidance situation ( 3). For cautionary
warnings, a major concern is determining the sensitivity of the alarm to avoid false
alarms. Excessive false alarms can cause drivers to ignore or disable the alarm.
Alternatively, if the alarm is not sensitive enough, the driver may not receive timely
warning, and an accident could result. One approach is to have the cautionary alarm vary.
Three acoustic variations in various combinations were examined. Participants felt the
greatest match between their sense of danger in the backing scene and the danger
portrayed by the alarm was when the loudness increased as the car approached the target.
The best acoustic warning design includes a constant pulse rate, constant pitch, and fast
variation of loudness ( 3).
Llaneras et al. completed a 2005 study concerned with the development of criteria for
developing driver interfaces for a rear obstacle detection system and different timing
algorithms to set off the alarm ( 34). The researchers tested drivers in a minivan and a
passenger sedan equipped with a prototype rear obstacle detection system ( 34). The
appropriateness of the warning timing algorithms was tested using an alerted backing
procedure wherein drivers backed to known obstacles and braked in response to the
warning. Additionally, a surprise event scenario was included in order to examine driver
reaction to the warning under unexpected conditions ( 34). While both timing algorithms
led to few target strikes, one algorithm elicited more acceptable ratings with fewer target
strikes and close calls, and less urgent braking ( 34). However, none of the interface
warning conditions reliably induced avoidance braking under the surprise event condition
( 34). The research was intended for use in developing improved warning systems;
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however we did not find any indication that manufactures have used the results to inform
new equipment designs.
Critics of using back- up alarms alone argue that they are not always enough to protect
pedestrian workers because the alarms do not always function, and on a noisy site
workers may hear back- up multiple alarms or get confused about the location of the
vehicle ( 15).
RADAR AND SONAR
Radar sensors emit high- frequency radio waves that detect objects’ position and velocity
relative to the vehicle on which they’re mounted. Sonar detectors use a sound transmitter
and receiver. Both are typically mounted on the rear of the vehicle. They emit an audio
warning inside the vehicle to alert the equipment operator ( 27). Both radar and sonar
technologies can work in conjunction with back- up alarms to comprise a comprehensive
warning system.
An early examination into radar systems published in 1991 looks at how contractors
avoid backing accidents by using motion detectors installed on trucks and heavy
equipment ( 7). The U. S. Bureau of Mines tested three principal types of motion detectors
( Doppler radar, ultrasonic wave, and infrared light) and concluded the following:
• Ultrasonic systems had a limited range but worked well in rough or dirty
environments.
• Infrared sensors worked despite a build- up of grime, but malfunctioned at slow
speeds or in bright light.
• Radar systems were the most immune to weather conditions ( 7).
A 1996 study explored community transportation vehicles and backing accidents and
referenced Caltrans’ evaluation of the Echovision rear obstacle detection system as a
means of reducing accidents and improving safety. Caltrans then listed the system as an
approved option in 1996 and as standard equipment in 1997 ( 16).
In 1997, Moffa et al. published an important report on radar and lidar crash
countermeasure technologies. The researchers focused on radar and lidar technologies
because of the relatively long ranges required for accident avoidance at a high closing
velocity ( 24). Results indicated that both radar and lidar are dependable and use for low-cost,
highly reliable components. Digital signal processors were also examined, and
requirements for processor speed, architecture, and memory were derived ( 24). In the
decade since the publication of this report, new research findings about into radar and
sonar systems may affect future equipment purchases.
The 2007 report, “ Front and Rear Vehicle Detection and Tracking in The Day and Night
Times Using Vision and Sonar Sensor Fusion,” proposed a vehicle detection and tracking
method that used vision and sonar sensors to detect objects and estimate distances under
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different light and road conditions ( 17). In the daytime, the system could create an image
that allowed the driver to clearly visualize the features and distance of objects behind the
vehicle. At night, it was able to detect bright regions caused by the headlights, taillights,
brake lights, an the like and aided the driver’s ability to see objects behind the vehicle
( 17).
Another report, “ Hardware Evaluation of Heavy Truck Side and Rear Object Detection
Systems,” focuses on two types of electronics- based object detection systems for heavy
truck applications: rear- sensing, and those sensing the presence of objects on the
vehicle’s right side ( 13). Three types of evaluation were performed: a hardware
performance measurement, a human factors assessment of driver/ system interfaces, and
an assessment of subjective driver reactions. The results of these evaluations indicated
that object detection system technology is still in the early stages of its development and
user- acceptance ( 13). Drivers of heavy trucks appreciate the value of these aids, but
improvements in the technology are needed before their full potential for preventing
crashes can be realized ( 13).
A series of four studies commissioned by the National Institute for Occupational Safety
and Health ( NIOSH) and the Spokane Research Laboratory evaluated radar and sensor
based collision- warning systems for construction equipment, heavy equipment, and off-road
dump trucks ( 27- 29). Below are some key findings from three of the studies that
contained particularly relevant results:.
• Camera and sensor systems are more reliable under warmer conditions and
experience difficulties under cold, snowy conditions. ( 29)
• They do not perform well in congested work areas. ( 27)
• The tendency to produce false alarms suggest that sensor- based systems for
proximity warning should be used in combination with devices such as cameras to
allow the operator to check the alarm source. ( 29)
• A radar system installed in large, off- road dump trucks reliably detected small
vehicles, people, and other equipment. ( 28)
A 2005 report published in Canada investigated the performance of different types of
sonar equipment in monitoring back- up proximity to reduce pedestrians’ risks from
reversing vehicles ( 14). Six commercial reversing aid systems that used ultrasonic sensor
technology were evaluated in laboratory tests consisting of 3- dimensional mapping of
detection zones, system response time, and durability, especially concerning the effects of
dust and dirt ( 14). In terms of durability and reaction times, all six systems performed
reliably ( 14). Their performance did not decrease significantly even with the sensors
covered with dust; however, they weren’t effective in protecting pedestrians, primarily
due to their limited detection distances ( 14). Even under ideal conditions, their
effectiveness was limited to vehicle speeds that were lower than those at which most
pedestrian collisions occur ( 14). The researchers suggest that other technologies could be
effective at higher vehicle speeds and that video cameras would be feasible because their
cost is steadily decreasing ( 14).
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CAMERAS AND VIDEO
Over the past 20 years, several works about automated driving systems dedicated to
collision avoidance have demonstrated the usefulness of still cameras and video in
providing information that allows the driver to easily process information while driving
or parking. Camera and video technologies may work in conjunction with back- up alarms
to comprise a comprehensive warning system.
A list of features included in the Safety Vision rear- vision camera system illustrates the
multi- faceted safety components of a camera system:
• ! Heavy duty design that can withstand harsh environments
• ! Black and white or color systems
• ! Infra- red illuminators for low- light working conditions
• ! Threaded and sealed connectors for water- tight connections
• ! Multi- sectional cables for easy maintenance
• ! Wide field of view
• ! Built- in microphone for crisp, clear audio
• ! High- impact- resistant housing
• ! Backlight compensation to control picture quality in all lighting conditions ( 5)
In 2006, the National Highway Traffic- Safety Administration ( NHTSA) issued a report to
Congress titled “ Vehicle Back- over Avoidance Technology Study” ( 31). The report
addressed the results of a NHTSA study of crashes involving passenger vehicles backing
over pedestrians and evaluated backing aids and educational efforts. NHTSA researchers
analyzed crash data, spoke with vehicle and equipment manufacturers, tested a
representative sample of backing aids, and performed a literature review. Of the
technologies tested, researchers determined that camera- based systems had the greatest
potential to provide drivers with reliable assistance in identifying people in the path of a
backing vehicle ( 31). The report cautioned, however, that it was important to obtain a
clear understanding of the environmental factors limiting the camera’s effectiveness and
the limits of the improvements in driver performance using such systems ( 31).
A 2005 e