2017 SWITRS Data Added to Transportation Injury Mapping System

March 21, 2018

The Transportation Injury Mapping System (TIMS) has been updated with 2017 SWITRS data!

ATP Hex Map graphic

Community Hex Map generated in ATP Maps & Summary Data tool

The Transportation Injury Mapping System (TIMS) has been developed by SafeTREC's GIS Program team to provide quick, easy and free access to California crash data that has been geo-coded to make it easy to map out crashes via a variety of...

Visualizing Teen Driver Safety Needs: SafeTREC researchers present at 2017 GIS Day

November 10, 2017

Teen Heat Map Presentation

State Superintendent of Public Instruction, Tom Torlakson, with staff from the California Department of Education, California Office of Traffic Safety and SafeTREC.

On November 2, 2017, SafeTREC co-director Jill Cooper and researchers SangHyouk Oum and Liwei Fu presented SafeTREC’s latest data and mapping analysis tool, the Teen Safety Heat Map at the 2017 Geographic Information Systems...

SafeTREC's CA Teen Driver Heat Map featured in CDE Driver Education Update

January 26, 2018

The California Young Driver Heat Map (Teen Safety Heat Map), a new geographic information system (GIS) resource developed by SafeTREC in partnership with the California Office of Traffic Safety (OTS) was recently highlighted in the Winter, 2017-2018 issue of the California Department of Education's CDE Driver Education Update. Teen Safety Heat Map Article

This data and mapping analysis tool was developed...

New Interactive Map of CPBST Program Now Available

December 13, 2017

Since 2009, UC Berkeley SafeTREC and California Walks (Cal Walks) have partnered together on the Community Pedestrian and Bicycle Safety Training (CPBST) program to train local neighborhood residents and safety advocates on how to improve pedestrian and bicycle safety and strengthen their collaboration with local officials and agency staff to make their communities safer and more pleasant to walk and bike.

As of 2017, SafeTREC and Cal Walks have...

Geocoding Police Collision Report Data from California: A Comprehensive Approach

Bigham, John M.
Rice, Thomas M.
Pande, Swati
Lee, Junhak
Park, Shin Hyoung
Gutierrez, Nicolas
Ragland, David R.


Collision geocoding is the process of assigning geographic descriptors, usually latitude and longitude coordinates, to a traffic collision record. On California police reports, relative collision location is recorded using a highway postmile marker or a street intersection. The objective of this study was to create a geocoded database of all police-reported, fatal and severe injury collisions in the California Statewide Integrated Traffic Records System (SWITRS) for years 1997-2006 for use by public agencies.


Geocoding was completed with a multi-step...

Investigating the Associations Between Road Network Structure and Non-motorist Accidents

Zhang, Yuanyuan
Bigham, John M.
Ragland, David R.
Chen, Xiaohong

Road networks channel traffic flow and can impact the volume and proximity of walking and bicycling. Therefore, the structure of road networks—the pattern by which roads are connected—can affect the safety of non-motorized road users. To understand the impact of roads’ structural features on pedestrian and bicyclist safety, this study analyzes the associations between road network structure and non-motorist-involved crashes using data from 321 census tracts in Alameda County, California. Average geodesic distance, network betweenness centrality, and an overall clustering coefficient...

Error Consideration for Geocoding Police Reported Collision Data in California

Bigham, John M.
Oum, Sang Hyouk

Geographic Information Systems (GIS) are frequently used to analyze collision data. In order to 3 utilize GIS, the data must be geocoded, or assigned a latitude and longitude coordinate by 4 translating a descriptive location onto street network data. However, the ability for accurate 5 spatial analysis can be limited by geocoding errors that may occur due to limitations in data 6 collection technologies, incorrect data entry due to human error, or inaccurate street reference 7 data. In the state of California there is an increased opportunity for data entry errors, given the 8 long...

Geocoding vehicle collisions on Korean expressways based on postmile referencing

Park, Shin Hyoung
Bigham, John M.
Kho, Seung-Young
Kang, Seungmo
Kim, Dong-Kyu

Geocoding is the process of assigning latitude and longitude coordinates to data that contain spatial information. Geocoded records of motor vehicle collisions are an invaluable resource for injury prevention researchers. The objective of this study is to apply the postmile referencing system for geocoding collisions on Korean expressways and summarize the methodology and results with comparative research efforts in the USA. A street network provided by Korea Expressway Corporation was cleaned and calibrated using ArcGIS and a customized Visual Basic for Applications (VBA) tool....

Evaluation of Wet Weather Accident Causation Criteria

Oh, Soonmi
Ragland, David R.
Chan, Ching-Yao

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP). The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the...

Evaluation of the Accuracy of Global Positioning System Coordinates for Collision Locations in California

Bigham, John M.
Strang, Garrett
Oum, Sang Hyouk

Traffic collision reports typically provide descriptive locations indicating where a collision occurred and referencing the nearest intersection. Global Positioning System (GPS) technology can be used to provide latitude and longitude coordinates in addition to the descriptive location and many states now include GPS coordinates in collision reports. However, research has shown that there is potential for numerous errors when police agencies use GPS to complete traffic collision reports. In California, GPS coordinates have been included in the statewide collision database since 2006...