Road fatalities are rare outcomes of events that occur in a small time-space region. Although the exact chain of events for each fatality is unique, there are inherent similarities between road fatalities. The science of road safety is dedicated to identifying such similarities, mainly using statistical analysis tools. Researchers typically analyze patterns that emerge over space, such as hot-spot studies, or patterns that emerge over time, such as before-after studies. Traffic research enumerates 84 parameters that characterize a road fatality. A vast number of papers have tried to...
The Pedestrian Safety Improvement Program is an effort of the California Department of Transportation (Caltrans) to identify and address systemic problems with regard to pedestrian safety in California, with the long-term goal of substantially reducing pedestrian fatalities and injuries in California. The efforts and findings presented in this report reflect the work of a team of experts in transportation engineering, transportation planning, public health, geographic information systems, and urban design from the UC Berkeley Safe Transportation Research & Education Center.
Secondary traffic accidents are generally recorded without being specifically noted as such in the accident database, leading to difficulty in the study of such accidents. Previous research generally classified secondary incidents by predefining fixed spatio-temporal boundaries—a method that can be very subjective. Using 10,762 accident records gathered from 2012 upstream loop detector data on a California interstate freeway, this paper proposes a dynamic method for more convincing and accurate classification based on traffic shock waves detected by the loop detectors. This method...
This paper presents a method to assess the safety of uncontrolled intersections considering both conflict probability and severity, which are two major properties of traffic conflicts. This method provides not only the safety level of the entire intersection but also the distribution of safety within intersections. Intersections are modelled by a two-dimensional Cartesian coordinate system and the internal space of intersections is divided into cells. Firstly, vehicle movement characteristics of at uncontrolled intersections are modelled. Secondly, conflict probability of each cell within...
UC Berkeley SafeTREC is excited to announce our 2026 virtual two-part Peer Exchange series: “Advancing safety through the CSSA.” The series, part of the Complete Streets Safety Assessment (CSSA) program, will feature two former participant communities as they reflect on their experiences with the program – from their initial application to the real-world safety impacts of their comprehensive safety reports.
UC Berkeley SafeTREC and Fehr & Peers are excited to announce the selection of 16 communities throughout California for our 2026 Complete Streets Safety Assessment (CSSA) program! These sites represent a diverse range of cities, counties, and tribal lands committed to eliminating traffic fatalities and improving mobility for all road users.
This paper documents findings from evaluating performances of three different methods for segmenting freeway sites for the purpose of identifying high collision concentration locations: Sliding Moving Window (SMW), Peak Searching (PS) and Continuous Risk Profile (CRP). The traffic collision data from sites segmented in each method under two different roadway definitions were used to estimate excess expected average crash frequency with Empirical Bayes adjustment with respect to two different sets of Safety Performance Functions (SPFs). The estimates from each of the methods were then used...
