Data Archives -

San Diego geocoded SWITRS data

As part of our ongoing work to test and improve our geocoding processes, we recently looked at SWITRS collision data for the City of San Diego. In my past work when attempting to geocode data for San Diego, we found the various street networks were quite outdated compared to other areas in California. I presumed it was due to rapid population growth but a quick Google search surprisingly showed that might not have necessarily been the case: http://www.sandiegouniontribune.com/news/2011/mar/08/san-diego-growth-last-decade-is-the-slowest-ever/ Regardless of the reasons, it was difficult to geocode collisions since there were many new streets in the suburban areas. In order to […]

Property Damage Only (PDO) collision count trends in California counties

Property Damage Only (PDO) collisions refer to any collision in which none of the involved parties were injured. In California there is a great deal of variability how PDO collisions are collected and reported by local police departments. Unlike injury involved collisions, it is not required to report PDO collisions to the Statewide Integrated Traffic Records System (SWITRS). Therefore individual police departments set their own standards on how to collect, manage and report PDO collisions. Due to this variability, most research and analyses typically exclude PDO collisions. It would not make sense to conduct a statewide study of all collisions […]

City of Los Angeles geocoded SWITRS data free download

UPDATE Geocoded SWITRS data is now provided through the City of Los Angeles Geohub. You can search for SWITRS to find the latest available data at: http://geohub.lacity.org/datasets?q=switrs The data originally linked on this blog post below is no longer updated. ————– On the heels of releasing the HSIP Helper a few weeks ago, we are now providing a full set of geocoded SWITRS data for the City of Los Angeles to planners, engineers, researchers, or anyone working with collision data in Los Angeles. While many of you have utilized the great service provided through TIMS at UC Berkeley, you may have […]

Collisions vs Injuries

Evaluations of collision data inevitably require summarizing the number of collisions or injuries occurring on a roadway or region. Target safety goals, baseline analyses of conditions and comparative rankings are all based on counts. However, when reviewing the numbers it’s important to make sure you are comparing apples to apples and not apples to oranges — aka collisions to injuries (or fatalities). During my time at UC Berkeley’s SafeTREC, this collisions vs injuries issue frequently presented itself and caused confusion during conversations or when preparing numbers for various reports and presentations. To dig deeper, let’s continue with the pedestrian collision […]

Querying for pedestrian related collisions

Collision data is inherently complicated since it attempts to aggregate all the elements of a collision into a nice, standardized database. The breadth of information available contributes to the complexity and can make it quite daunting for someone to understand without extensive experience working with the data. I wanted to address some of the more common questions that I have heard over the years and hopefully provide sufficient explanations in a series of blog posts. Given the interest in the built environment and the focus on improving conditions for pedestrians, a common data question is: How many pedestrian collisions were […]

Collision data GPS coordinate accuracy

The usefulness of RoadSafe GIS or any other software solution is heavily dependent on the quality of the input data. For collision data, the location information is particularly important and in recent years police officers have begun including Global Positioning System (GPS) coordinates in collision reports. Hypothetically using a GPS coordinate would be a better solution than geocoding collision data based on the intersection name, but the reality is that GPS coordinates may not be quite ready for prime time. One of my last tasks at UC Berkeley was to finish an evaluation of the GPS coordinate accuracy for California […]