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Open Access Publications from the University of California

About

The Safe Transportation Research and Education Center (SafeTREC) mission is to inform decision-making and empower communities to improve roadway safety for all.

Founded in 2000 as the Traffic Safety Center (TSC), the Center was renamed in 2009 to more accurately reflect the mission to encompass safety and travel risk in a multimodal transportation system; a robust and diverse research agenda across multiple disciplines; and development and enhancement of curriculum, training, and outreach on the graduate and undergraduate levels, as well as for professionals and members of the community.

SafeTREC is part of the University of California, Berkeley, and is affiliated with the School of Public Health and the Institute of Transportation Studies, with additional partnerships with the Department of City and Regional Planning, Public Policy, and Transportation Engineering. Our research is carried out by faculty at UC Berkeley with assistance from post-doctoral scholars, research staff, and graduate student researchers. We also help the California Office of Traffic Safety administer its Community Pedestrian and Bicycle Safety Training workshops and support various safety initiatives from other California agencies, Including the California Department of Transportation (Caltrans). 

 SafeTREC's three emphasis areas are:

  • Data Analysis and Data Tools is a necessity for understanding safety/mobility in transportation / land use planning in California.  SafeTREC will build on current large scale data efforts (geocoding 15 years of traffic crashes in California, adding pedestrian and bicycle infrastructure elements to the State Highway data base, building a statewide Tribal Road Safety Data Base) to construct state-of-the-art data analysis and mapping tools for use by government agencies, researchers, and the general public.
  • Technology for Road Safety, including crash warning and avoidance systems, smart infrastructure sensing systems, and automated vehicles. SafeTREC will be in the forefront of evaluating the benefits and costs of these rapidly emerging technologies. This emphasis area will also utilize technology for in-depth analysis of crash reports, data visualization techniques, and developing novel transportation safety management methods.
  • Policy Analysis and Community Outreach will continue to be a necessity to connect with California’s extremely diverse communities to improve road safety and encourage active transportation. SafeTREC will build on existing policy analyses (e.g., Safe Routes to School) and community outreach (e.g., Community Pedestrian and Bicycle Safety Training, data analyses and presentations for local governmental agencies) to create a national model for policy analysis and community outreach.

Safe Transportation Research & Education Center

There are 245 publications in this collection, published between 2002 and 2024.
Policy Brief (2)

Conducting Community Engagement with a Safe System Lens

Over 3,600 people died in traffic crashes in California in 2019; more than one in four people who died was a pedestrian or bicyclist (NHTSA). The burden of death and injury is unequally distributed - based on mode type, on race and ethnicity, and on income - as a consequence of historic and structurally inequitable funding and policy decisions (Archer, Sandt, Santana). Our current road network is a dichotomy of areas that connect people to things they need and underserved communities with restricted mobility. The Safe System approach offers transportation professionals with a new way of approaching safety and to improve roadways and mobility.

Originally introduced in Sweden in 1997, the Safe System approach has been gaining momentum in California and nationally with severalhigh visibility reports and publications by the National Transportation Safety Board (NTSB), Towards Zero Foundation, the Safe System Consortium, and the National Safety Council. This approach views human life and health as the paramount consideration when designing a road network (Towards Zero Foundation). The goal of a Safe System is to eliminate fatal and serious injuries for all road users by proactively putting safeguards in place and working towards sustainable mobility.

Traditionally, human behavior was considered to be the primary variable associated with traffic injury. The Safe System approach refocuses efforts to emphasize transportation system design and operation. It inherently places an emphasis on non-motorized users who are at a higher risk of death or serious injury. Most resources, including the Federal Highway Administration (FHWA), identify the key components of a Safe System as some combination of safe road users, safe vehicles, safe speeds, safe roads, and post-crash care. This Safe System further anticipates that people will make mistakes or have momentary lapses of attention, and acknowledges that the human body has a limited injury tolerance. This approach works to improve safety for all road users through multiple layers of protection, where no individual layer is 100% protective, but when several layers are combined, the overall risk is reduced.

Few resources, if any, address how to apply the Safe System framework in community engagement and planning efforts. As written, this approach relies primarily on transportation agencies to commit to a paradigm shift and adapt their work accordingly. Through our Community Pedestrian and Bicycle Safety Training Program, UC Berkeley Safe Transportation Research and Education Center (SafeTREC) and the nonprofit agency, California Walks (Cal Walks), adapted FHWA’s Safe System elements and principles to not only make it more applicable for grassroots community engagement but also to strengthen the impact of the approach. This brief will provide an overview of our thought process and set the stage for future efforts.

Engagement of Latine Communities in Transportation Safety

Public participation in government is a foundation of democracy; however, it exists on a spectrum. In the field of transportation, decision-makers may seek information by simply making public announcements to invite input. Alternatively, governments devote resources to conduct thoughtful and extensive outreach to seek meaningful input. Recently, professionals and policymakers have considered an equity approach not only to reach and engage a diverse, representative group of community members, but to develop plans, projects, and policies that are inclusive of the community. Engaging Latine1 communities requires rethinking traditional engagement and developing strategies that have considerations for the range of factors that shape this diverse community’s experience, including culture, social inequities, and socio- and geopolitical factors. This brief highlights a few best practices for engaging Latine communities.

Research Brief (20)

Towards a Safer California: Addressing the Road Safety Needs of Older Adults

With an aging state population, it is crucial to understand the factors that contribute to road safety among adults aged 65 and older and identify at-risk neighborhoods for targeted interventions. In this context, this report analyzes fatal and serious injury (FSI) trends and patterns among aging road users, including older pedestrians and bicyclists, with a focus on identifying neighborhoods at risk for crashes based on senior FSI rates. 2178 census tracts (32.7%) were deemed as being potential at-risk neighborhoods, as they all exceeded the state average senior FSI rate of 120 per 100,000 individuals (0.12%). The report also discusses factors that contribute to road safety among older adults, including physical changes associated with aging and the impact of new mobility technologies. By identifying at-risk neighborhoods and exploring factors that contribute to senior road safety, this report aims to inform targeted interventions to improve road safety for older adults.

Shared Responsibility for Road Safety in Safe Systems Context

Safe Systems is an approach to road safety that envisions the elimination of fatal and serious injuries and seeks to provide both a theoretical framework and practical roadmap for accomplishing such an ambitious goal. The Safe Systems approach involves a paradigm shift from traditional approaches to road safety planning and responsibility. This fact sheet discusses a principle integral to a Safe Systems Approach, shared responsibility for road safety.

Community Trainings at Work: An Evaluation of Community Pedestrian and Bicycle Safety Trainings

The Community Pedestrian Bicycle Safety Training (CPBST) program trains and mobilizes communities to address pedestrian and bicycle safety and strengthens collaboration with local officials and agency staff. This research brief summarizes an evaluation of the CPBST program completed in 2018. 

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Research Highlight (8)

2023 CPBSP Annual Report

UC Berkeley SafeTREC, in collaboration with California Walks, launched the Community Pedestrian and Bicycle Safety Program (CPBSP) to reduce pedestrian and bicyclist fatalities and serious injuries in California. We partner with communities across California to discuss, plan, and implement safety improvements and projects. The CPBSP prioritizes working in communities that are at disproportionate risk for road traffic injuries and addressing the safety needs of people who are underserved by traditional transportation resources and planning.

This report provides highlights from the 2023 CPBSP.

Impact of the Community Pedestrian and Bicycle Safety Training Program: Insights from the 2022 Follow-Up Survey

The Community Pedestrian Bicycle Safety Training (CPBST) program is a collaborative project between UC Berkeley Safe Transportation Research and Education Center (SafeTREC) and California Walks (Cal Walks) that seeks to assist communities with three goals:

Identifying and better understanding their local transportation safety needs;Developing and strengthening local partnerships between various stakeholders in their community; andGenerating a community-specific action plan for improving the safety of active transportation in their area.

These objectives are pursued through pedestrian and bicycle safety training workshops hosted by SafeTREC and Cal Walks in collaboration with community partners. Over 112 workshops have been conducted since 2009, and the program continues to provide trainings in 2022. Planning a workshop involves SafeTREC and Cal Walks working with a planning committee consisting of local stakeholders to schedule the workshop, recruit participants for the workshop, and work with the participants to develop a unique action plan with short-term, medium-term, and long-term goals for improving walking and biking safety and mobility (Leckie et al., 2021). A major feature of the workshop is an assessment of pedestrian and bicycle conditions in areas of interest in the community. 

Community Pedestrian and Bicycle Safety Training (CPBST) Program Workshop Follow-Up Survey Highlights

The Community Pedestrian and Bicycle Safety Training Program (CPBST) is a joint project of the University of California Berkeley’s Safe Transportation Research and Education Center (SafeTREC) and California Walks (Cal Walks). Founded in 2009, the purpose of the CPBST is to: 

1. Educate local residents and safety advocates on how to improve pedestrian and bicycle safety;

2.Empower community partners to advocate for safety improvements in their neighborhoods; and

3. Strengthen collaborations with local officials and agency staff to make California neighborhoods safer and more pleansant for walking and bicycling.

SafeTREC and Cal Walks work with a Planning Committee, a group of local safety stakeholders, to convene a workshop, recruit participants, and tailor the curriculum to address the community’s needs and priorities. During the workshop, participants conduct a walking and biking assessment of priority areas in the community, learn about Safe System strategies to address walking and biking concerns, and develop an action plan with short-, mid-, and long-term recommendations. 

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Research Reports (121)

Airports and Bicycles: what are the obstacles and incentives for operators 1 to improve bicycle access?

In this paper we use a case study approach to examine how airport operators are addressing bicycle access to their properties and the motivations and obstacles they face, in light of new policies to integrate bicycles, along with transit and walking, into transportation planning, design and construction, and to increase bicycles’ role in the transportation system.

Eight influential elements emerged from our review of policy documents and research literature. We used them to guide interviews with key informants. The eight elements are: governance structure, location, access roads, self-perceived environmental stewardship, spending restrictions on non-aviation transportation improvements, proximity to transit, policies and mandates to reduce environmental impacts and land use constraints. We report on seven cases, selected on the basis of inclusion in studies on key aspects of airport ground access and, for one, identification as exemplary. They are: Oakland International Airport, San Francisco International Airport, Los Angeles International Airport, Seattle-Tacoma International Airport, Boston Logan International Airport Minneapolis-St. Paul International Airport, and Portland, an exemplar recommended by several key informants. 

We limit our discussion to employee bicycle access because that has been the focus of airport operators that have made these investments and programs to reduce single-occupancy vehicle travel at airports.

In aggregating the interviews, we identified replicable approaches to improving bicycle access. We also identified examples of innovative funding for multi-modal access using revenues generated by airport Passenger Facilities Charges. Finally, we identified areas for additional research: airport employee commute needs, ground access mode choice and operator costs and benefits of bicycle access investments.

  • 1 supplemental PDF

Safety and Other Impacts of Vehicle Impound Enforcement

California vehicle impound law took affect on January 1, 1995. The law allows a police officer to seize a vehicle operated by a person whose license is suspended or revoked or who has never been issued a license. The seized vehicle shall then be impounded for 30 days. In California, a driver must be stopped for some other infraction before his/her license can be checked. The purpose of this evaluation is to assess the impact of Upland's vehicle impound program on traffic safety (crashes and on-the-road behavior) and police department resources and operations.

Evaluation of Traffic and Environment Effects on Skid Resistance in California

Skid resistance is one of the important serviceability indicators related to safety on wet pavements. There is a need to manage skid resistance systematically to maintain the level of safety performance of roadway surfaces. This study focused on the development of a skid resistance deterioration model based on the analysis of skid data inventory collected in California. The California Department of Transportation (Caltrans) has collected skid resistance data across the complete state highway network over the past two decades using a standard locked-wheel skid trailer, ASTM E-274. This study utilizes skid data collected on more than 300 miles of asphalt concrete freeway in California over a period of twenty years. Most of the possible factors found in previous studies to influence skid resistance were considered. Panel data parameter estimation methods were used. The results indicate that factors with the largest effects on skid resistance are the age of pavement, ADT, temperature, precipitation, and the length of the period since the last significant precipitation.

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SafeTREC Webinars (25)

Methods and Technologies for Pedestrian and Bicycle Volume Data Collection

In this talk, an overview of the recently completed National Cooperative Highways Research Program project 07-19 will be presented. In NCHRP 07-19, research was conducted on a variety of methods and technologies for collecting bicyclist and pedestrian volume data. Research included a practitioner's survey, in-depth interviews with count program managers, and field testing and accuracy evaluation of six counting technologies. Counters were installed at roughly 15 different sites and evaluated for precision and reliability. The main product of this project is a guidebook on conducting counts of pedestrians and bicyclists, to be published in early 2015.

  • 1 supplemental PDF
  • 1 supplemental audio file

Frank Proulx, NCHRP 07-19: Methods and Technologies for Pedestrian and Bicycle Volume Data Collection

Abstract: In this talk, an overview of the recently completed National Cooperative Highways Research Program project 07-19 will be presented. In NCHRP 07-19, research was conducted on a variety of methods and technologies for collecting bicyclist and pedestrian volume data. Research included a practitioner's survey, in-depth interviews with count program managers, and field testing and accuracy evaluation of six counting technologies. Counters were installed at roughly 15 different sites and evaluated for precision and reliability. The main product of this project is a guidebook on conducting counts of pedestrians and bicyclists, to be published in early 2015.

  • 1 supplemental PDF
  • 1 supplemental audio file

CA 13 Data Webinar

SafeTREC webinar on Challenge Area 13 regarding Bicycle Safety data.

  • 1 supplemental audio file
  • 1 supplemental ZIP
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Technical Report (10)

California Traffic Safety Survey 2018: Data Analysis and Comparison with 2010-2017 Survey Data Results

The 2018 California Traffic Safety Study is the ninth wave of a statewide representative survey of California vehicle drivers on traffic safety perceptions, distracted driving and level of awareness of traffic safety media outreach campaigns. The following data analyses is based on 1,395 survey responses collected in August and September of 2018.

The analyzed data only includes the valid answers for survey items, while excluding all reported “Don’t know” responses as well as response refusals. For this reason, the valid percentage of responses differs for each question due to the number of valid answers given to a particular question. The total answer per survey question is reflected in the total number of completed surveys, which are listed in each table. In addition, some questions are skipped based on selected answer and the sample sizes for each survey item vary accordingly. Due to rounding to one decimal point, some percentages presented do not always add up to the exact value of 100.0%.

All comparisons to previous years’ data refer to the comparable longitudinal field surveys conducted with California vehicle drivers since 2010. The scope and overall sample size of the 2018 survey was comparable to the sample size of the 2017 data collection.

In total, 1,395 vehicle drivers were intercepted for the study, resulting in an overall confidence interval of +/- 2.63, at a confidence level of 95%.

California Traffic Safety Survey 2023: Data Analysis and Comparison with 2010-2022 Survey Data Results

Similar to the survey waves since 2020, the 2023 California Traffic Safety Public Opinion Study was conducted by Ewald & Wasserman Research (E&W) on behalf of the California Office of Traffic Safety (OTS) and the Safe Transportation Research and Education Center of UC Berkeley (SafeTREC), with an online self-administered survey. Survey panelists were provided through Marketing Services Group, a commercial sample and panel vendor. 

The eligibility criteria for participating in the study were possessing a valid California driver’s license and being 18 years or older. Eligible respondents were forwarded to an online survey portal programmed and managed by E&W. To manage the sample composition and to ensure a similar distribution of age and gender compared to the California census and previous waves of the Traffic Safety Study, quotas by gender and six age groups were implemented. 

Participation in the survey was anonymous, and a total of 2,815 responses were collected in April, 2023. 

This report describes the findings of the 2023 Traffic Safety Public Opinion Study, along with a comparison of previous years of data, which include opinions from a representative sample of California drivers on a range of factors affecting traffic safety. 

2024 CPBSP Highlights

The Community Pedestrian and Bicycle Safety Program (CPBSP) was launched by the UC Berkeley Safe Transportation Research and Education Center (SafeTREC) in collaboration with California Walks to reduce pedestrian and bicycle fatalities and serious injuries in California communities. The CPBSP prioritizes working in communities at disproportionate risk for road traffc injuries and addressing the safety needs of people who are underserved by traditional transportation resources and planning.

The CPBSP engages participants in active transportation planning and strengthens the capacity of community partners to create safer and more accessible streets for everyone walking and biking. The CPBSP educates communities with an adapted Safe System approach, shares pedestrian and bicycle safety strategies and best practices, conducts on-the-ground walking safety assessments, provides site-specifc crash data analysis, and offers follow-up services to help communities advance their safety goals.

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Working Papers (9)

Emergency Medical Services (EMS) and the California EMS Information System (CEMSIS) Working Paper

This study examines data from the California EMS Information System (CEMSIS) to identify factors that influence prehospital time for EMS events related to motor vehicle collisions (MVCs). While only 19 percent of the United States population resides in rural areas, over half of all traffic fatalities involve rural motor vehicle collisions. Rural and urban MVCs result in similar injury severities, however relative inaccessibility of trauma centers and prehospital EMS time (activation, response, and transport time) likely contribute to the generally higher mortality rate in rural areas. For the present study, 24 CEMSIS data variables were requested, many of which involved missing data, which severely restricted the potential analysis of the impact of EMS response times. However, the findings did show that average overall EMS time (including response, scene and transport time) were approximately twice as long for collisions in rural zip codes compared with urban zip codes. Several limitations influence the interpretation of these results. Data on prehospital EMS times is missing for much of the state—even for zip codes with records of EMS events, data is likely incomplete. In addition, zip code level location data is insufficient for adequate study of the effects of the built environment and road network on prehospital time. Furthermore, according to the National EMS Information System (NEMSIS) User Manual, the national dataset suffers from selection and information bias, which are likely also present in the CEMSIS data. Although the present study cannot analyze the effect of longer prehospital times on patient outcome, other research has found that longer prehospital times may negatively impact patient health. Recommendations for reducing time from injury to appropriate medical care in rural areas include improving cell phone coverage, compliance of rural 911 center with FCC wireless, use of GPS technology, and integration of automatic vehicle location and computer aided navigation technologies into all computer-aided dispatch systems. In addition, CEMSIS should improve the coverage of their dataset and ensure that all EMS activities are recorded. To expand the type of analyses that can be conducted using CEMSIS data, EMS records must include fields that allow them to be linked to hospital and police datasets. When such data becomes available, research must be conducted to determine whether prehospital time is significantly related to patient outcome following motor vehicle collisions.

How Common is Pedestrian Travel To, From, and Within Shopping Districts?

Growing interest in sustainable transportation systems and livable communities has created a need for more complete measures of pedestrian travel. Yet, many performance measures do not account for short pedestrian movements, such as walking between stores in a shopping district, walking from a street parking space to a building entrance, or walking from a bus stop to home. This study uses a 2009 intercept survey and the 2009 National Household Travel Survey to quantify pedestrian travel to, from, and within 20 San Francisco Bay Area shopping districts. Overall, walking was the primary travel mode for 21% of intercept survey and 10% of NHTS tours with stops in these shopping districts. However, detailed analysis of pedestrian movements showed that walking was common on respondent tours (52% of intercept survey tours included some walking) and that walking was used on the majority of trips within these shopping districts (65% of intercept survey trips and 71% of NHTS trips within the shopping districts were made by walking). In general, Urban Core and Suburban Main Street shopping districts had higher levels of pedestrian activity than Suburban Thoroughfare and Suburban Shopping Center shopping districts. The detailed analysis in this paper provides a more complete picture of pedestrian activity than is commonly shown by national and regional household survey summaries. 

Missed or Delayed Medical Care Appointments by Older Users of Nonemergency Medical Transportation Services

Non-emergency medical transportation (NEMT) can prevent emergency care as a result of delayed or missed medical appointments. Medicaid provides NEMT for low income individuals who have no other means of transportation and this is a critical component of the health care delivery system. This study examined cancelled trips in Medicaid adults age 65+ to explore whether barriers persist for a growing segment of the population who face particular challenges of age-related declines in health and function. Multivariate logistic regression analyses were conducted using transportation brokerage data for Delaware members who intended to travel during 2008-2010, modeling the odds of all cancellations and then these mutually exclusive types: (1) client cancelled; (2) client obtained alternative transportation; and (3) client cancelled due to health. Over half of the cancelled trips were attributed to client reasons. Black race was associated with client canceling (OR=1.4) and canceling due to alternative transportation (OR=1.9). Compared to dialysis, trips for other medical care were more likely to be cancelled for client and health reasons (ORs ranged 1.6-7.9). Higher levels of service increased cancelling for health reasons (OR=2.9 stretcher; OR=1.8 wheelchair). Finally, pre-scheduled or subscription trips were less likely to be cancelled and client factors differed for the cancellation of trips that were not regularly scheduled. The results of this initial study confirm that for this population additional transportation services are often not available and that more support for utilizing NEMT may be needed. Future research should evaluate persistent barriers, service delivery, and long-term outcomes. 

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