SafeTREC

Giving Cycling the Green Light: An Overview of Transportation in Ireland and the Design of the National Cycle Network

Manton, Richard
2013

Similarly to the US, driving a car to work continues to gain ground in Ireland and the country is presented with major challenges in environment and health as a consequence. In safety, at least, Ireland has had some major successes. In 40 years, the number of fatalities has fallen from 640 to 162, a drop of 75%. Such improvements in road safety have been attributed to a combination of education, enforcement and engineering. Pedestrian and cyclist fatalities have each fallen by 66% in 20 years, however, this could be attributed to the lower numbers of people walking and cycling....

Gap Acceptance for Vehicles Turning Left Across On-Coming Traffic: Implications for Intersection Decision Support Design

Ragland, David R.
Arroyo, Sofia
Shladover, Steven E.
Misener, James A.
Chan, Ching-Yao
2005

A left-turning vehicle (Subject Vehicle, SV) attempting to cross the path of an oncoming vehicle (Principal Other Vehicle, POV) at an intersection typically does not have the right of way. The main task of the SV driver is to find an adequate opportunity in opposing traffic to initiate the left-turn maneuver. To reduce the probability of a conflict, warning systems, such as Intersection Decision Support (IDS) systems, are being developed. These systems alert drivers of SV vehicles attempting to negotiate a left turnabout traffic approaching from the opposite direction. The current paper (i...

Comparison of Collisions on HOV Facilities with Limited and Continuous Access

Jang, Kitae
Chung, Koohong
Ragland, David R.
Chan, Ching-Yao
2008

This paper describes comparisons of traffic safety during the morning and afternoon peak hours in extended stretches of eight High Occupancy Vehicle (HOV) lanes with two different types of access – four corridors with continuous access and the others with limited access. Traffic collision patterns in two different types of HOV lanes were investigated by evaluating 1) the differences in collision distribution, severity, types of collisions and per lane traffic utilization, 2) spatial distribution of collision concentrations by using Continuous Risk Profile (CRP) approach, and 3) collision...

A Zoox and an e-bike collided in S.F. Here’s what it says about robotaxi safety

May 13, 2025

San Francisco Chronicle Scott Moura, Faculty Director of Partners for Advanced Transportation Technology (PATH) and Professor of Civil and Environmental Engineering, alongside Matt Raifman SafeTREC researcher, and Steven Shadover PATH researcher discuss A Zoox and an e-...

High Collision Concentration Location: Table C Evaluation and Recommendations

Ragland, David R.
Chan, Ching-Yao
2007

This report describes the research work that was conducted under PATH Task Order 5215 and its extension Task Order 6215, “Methods for Identifying High-Concentration Collision Locations (HCCL).” The subject matter is related to regularly published Caltrans reports, so-called Table C, that are used to screen for and investigate locations within the California State Highway System that have collision frequencies significantly greater than the base or expected numbers when compared to other locations. The accuracy and reliability of such reports are critical as Table C is the basis for follow-...

A Comparative Analysis of Pedestrian and Bicyclist Safety Around University Campuses

Grembek, Offer
Medury, Aditya
Orrick, Phyllis
Leung, Katherine
Ragland, David R.
Loukaitou-Sideris, Anastasia
Fink, Camille
Resnick, Justin
Wong, Norman
Shafizadeh, Kevan
Khan, Ghazan
2014

Large college campuses generate considerable volumes of traffic in a variety of modes, and in greater numbers, than found in most U.S. settings. This setting presents a unique study opportunity, as well as a significant potential for conflicts between motorized and non-motorized users of the transportation system, surrounded as most campuses are by mixed-use environments e.g. retail, restaurant, entertainment and high-density residential facilities such as apartments and dorms. At the same time, university campuses are also typically characterized by a central core area where most trips...

Performance Measures for Complete, Green Streets: A Proposal for Urban Arterials in California

Sanders, Rebecca
Macdonald, Elizabeth
Anderson, Alia
2010

The California Department of Transportation (Caltrans or “Department”) manages more than 15,000 miles of state highways, ranging in scale and function from local streets to interstate highways. Historically, Caltrans has been governed by the principles of highway engineering, which focus on providing mobility to motorized vehicles. Over the past decade, however, the Department has joined in a national movement to better incorporate non-motorized transportation and community-level outcomes into its transportation decision-making framework, embodied by the approach known as "Complete Streets...

The Continuing Debate about Safety in Numbers—Data From Oakland, CA

Geyer, Judy
Raford, Noah
Ragland, David
Pham, Trinh
2005

The primary objective of this paper is to review the appropriate use of ratio variables in the study of pedestrian injury exposure. We provide a discussion that rejects the assumption that the relationship between a random variable (e.g., a population X) and a ratio (e.g., injury or disease per population Y/X) is necessarily negative. In the study of pedestrian risk, the null hypothesis is that pedestrian injury risk is constant with respect to pedestrian volume. This study employs a unique data set containing the number of pedestrian collisions, average annual pedestrian volume, average...

Safe Routes to School Safety and Mobility Analysis

Orenstein, Marla R.
Gutierrez, Nicolas
Rice, Thomas M.
Cooper, Jill F.
Ragland, David R.
2007

This report evaluates the SR2S program for a number of mandated issues: (i) The effectiveness of the program in reducing crashes, injuries and fatalities involving children in the vicinity of the projects; (ii) The impact of the program on levels of walking and bicycling to school; and (iii) The safety benefits of the program in comparison with other highway safety programs.

Space Syntax: An Innovative Pedestrian Volume Modeling Tool for Pedestrian Safety

Raford, Noah
Ragland, David R.
2003

This paper describes an innovative pedestrian modeling technique known as Space Syntax, which was used to create estimates of pedestrian volumes for the city of Oakland, California. These estimates were used to calculate pedestrian exposure rates and to create a Relative Risk Index for the city’s first pedestrian master plan. A major challenge facing planners, transportation engineers, and pedestrian-safety advocates is the lack of detailed and high quality pedestrian-exposure data. Exposure is defined as the rate of contact with a potentially harmful agent or event. Pedestrian exposure is...