Evaluation

Using Geographically Weighted Poisson Regression for county-level crash modeling in California

Li, Zhibin
Wang, Wei
Liu, Pan
Bigham, John M.
Ragland, David R.
2013

Development of crash prediction models at the county-level has drawn the interests of state agencies for forecasting the normal level of traffic safety according to a series of countywide characteristics. A common technique for the county-level crash modeling is the generalized linear modeling (GLM) procedure. However, the GLM fails to capture the spatial heterogeneity that exists in the relationship between crash counts and explanatory variables over counties. This study aims to evaluate the use of a Geographically Weighted Poisson Regression (GWPR) to capture these spatially varying...

Strategies for Reducing Pedestrian and Bicyclist Injury at the Corridor Level

Grembek, Offer
Zhang, Yuanyuan
Yavari, Afsaneh
Yang, Zhao
Ragland, David R.
2013

A systemic approach for identifying potential safety countermeasures and implementing them across groups of locations sharing the same risk characteristics has been developed for pedestrian-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injury. Data collected between 1998 and 2007 from a 16.5-mile section of San Pablo Avenue (SR 123) in the San Francisco East Bay was used as the study area. A database containing all...

Estimation of Pedestrian Risk Exposure in Urban Areas : Case studies in the US and in France

Do, Minh-Tan
Grembek, Offer
Cerezo, Veronique
2013
The paper deals with the estimation of pedestrian risk exposure in urban areas. The approach proposed is based, on the one hand, on a spatial analysis technique called Space Syntax that characterizes the street integration - how streets are connected to each other - which gives rise to a natural movement of persons, and on the other hand, on land-use which acts as a multiplier or a divider of the original flows. Street integration is weighted by factors related to land use to better captures the heterogeneity of street-blocks. The method is applied to two radically different urban spaces: the...

Surrogate safety measure for evaluating rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks

Li, Zhibin
Ahn, Seongchae
Chung, Koohong
Ragland, David R.
Wang, Wei
Yu, Jeong Whon
2013

This study presents a surrogate safety measure for evaluating the rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks using aggregated traffic data from ordinary loop detectors. The attributes of kinematic waves that accompany rear-end collisions and the traffic conditions at detector stations spanning the collision locations were examined to develop the rear-end collision risk index (RCRI). Together with RCRI, standard deviations in occupancy were used to develop a logistic regression model for estimating rear-end collision likelihood near freeway...

Deadline extended! Apply now for a Complete Streets Safety Assessment by January 30th

January 22, 2026
Apply by January 30th to improve pedestrian and bicyclist safety in your community!

Students in crosswalk in front of Branham High School

Deadline extended! Apply now for the UC Berkeley Safe Transportation Research and Education Center (SafeTREC)...

2026 SafeTREC program applications are now open!

November 21, 2025
Apply now for our 2026 programs!

A group of twelve people wearing fluorescent safety vests stand together to discuss roadway conditions and concerns.

The UC Berkeley Safe Transportation Research and Education Center (SafeTREC) is excited to announce applications are now being accepted for...

California Safe System Institute for Road Safety Executive Summary

UC Berkeley SafeTREC
2025

In the summer of 2025, the UC Berkeley Safe Transportation Research and Education Center (SafeTREC) conducted a Needs Assessment to explore the need for, and interest in, a program to support and nurture California communities’ road safety work to align with an effective Safe System Approach. As part of the Assessment, interviews and surveys were conducted, finding strong interest in such assistance, particularly for peer learning, leadership support opportunities, and more concrete examples of successes to inform individual communities’ work.

2025 Follow-up survey highlights the impact of the Community Pedestrian and Bicycle Safety Training

August 6, 2025
Preliminary Statewide Integrated Traffic Records System (SWITRS) data for 2024 indicates that traffic crashes caused 3,376 preventable deaths statewide, of which 950 were pedestrians and 148 bicyclists. Additionally, in 2024, there were 16,142 people seriously injured in traffic crashes in California, including 2,531 pedestrians and 1,255 bicyclists. These deaths are unacceptable and preventable. Ensuring that our communities are safe for walking, biking and rolling is critical for community...