Safety & Collisions

As part of our on-going Maps and Data series we want to tackle the issues of collisions and roadway safety. Thanks to work done by the Safe Transportation Research and Education Center (SafeTREC) at the University of California, Berkeley, using data provided by the California Highway Patrol through their Statewide Integrated Traffic Records System, also know as SWITRS, historic collision data in Los Angeles is readily available for display and analysis.

Non-highway collisions between 2000 – 2009


Shown here are collisions recorded during the 10-year period between 2000 and 2009 on Los Angeles city streets (non-highway). The collisions are clustered at the intersection level and coded by the mode involved. The information illuminates certain areas of the City where there are a relatively high number of collisions. In particular, the Central City area of Los Angeles has had a high concentration of bicycle and pedestrian collisions.

Bicycle and Pedestrian Collisions in the Central City Area

On the citywide scale the data was used to create this list, which places the intersections that had the most collisions during the 10-year period in rank order.

Intersections in Los Angeles with the highest incidents of pedestrian, bicycle, and auto-only collisions between 2000 and 2009.

Dynamic Mapping

While our maps and data are static, the Transportation Injury Mapping System (TIMS) website allows users to drill down to their city/neighborhood/street and view the number, type,  and severity of collisions over a given time frame. Also available is statistical data on the primary factors involved in the collisions. Common factors attributed to collisions are  unsafe lane changes, following too closely, and, surprisingly, driving on the wrong side of the road. However, the most common factor attributed to collisions is driving at unsafe speeds.

SWITRS GIS Mapping tool made available by the Transportation Injury Mapping System


The information visualized through these maps illuminates particular areas of the City where there are a relatively high number of collisions. The type of collision also provides the City certain indications on what specific measures can be taken to limit future incidents. Given that excessive speed is the most cited factor in collisions, targeted reductions in speed could go a long way to reducing the number of collisions in Los Angeles. Pedestrians and bicyclists are of particularly vulnerable in collisions with cars, especially when those vehicles are traveling at increased speeds.

The problem of speed is two-fold – at higher speeds bicyclists and pedestrians become less visible and more vulnerable:

1. Since the human brain can only process a finite amount of visual information, the field of vision reduces significantly as the speed of travel increases, as illustrated below:

As speed increases, the field of vision narrows. (Image:

At faster speeds the field of vision narrows and the periphery, often where pedestrians or bicycles would be located, fades from view.

2. The second problem with increased speed is the likelihood of injury and death quickly increases:

What We’ve Heard

Roadway safety for everyone will be an fundamental goal of the Mobility Element. Recent tragic pedestrian and bicycle accidents have brought safety issues to the fore in many areas of the city. Also groups like Los Angeles Walks and the Los Angeles County Bicycle Coalition have made safety an underpinning of their advocacy work and have raised awareness of the safety needs of bicyclists and pedestrians. Through our various outreach efforts we have heard overwhelmingly that pedestrian and bicycle safety is a fundamental concern of many Angelenos.

Many of our participants have suggested safety enhancements to our streets, such as separated bicycle lanes to protect cyclists and reduced traffic speeds, more visible crosswalks, and bulb-outs to provide added safety for pedestrians. Together with enforcement and education, the Mobility Plan will add components of the 3rd ‘E’ of traffic safety: engineering. Hopefully safety measures strategically implemented throughout the city can dramatically reduce the number and severity of collisions in Los Angeles.

This entry was posted in Maps & Data and tagged , , , . Bookmark the permalink.

2 Responses to Safety & Collisions

  1. Pingback: Safety First | LA/2B

  2. Pingback: Complete Streets Networks, Part 3: Pedestrian Enhancements | LA/2B

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s