Mapping Santa Monica’s Bike Traffic & Collisions

From 2009 to 2011, Los Angeles County has seen a 32% increase in bicycle traffic (LACBC). In this same period, there were 11,025 reported motorist/bicyclist collisions, 63 ending in cyclists fatalities (TIMS). The City of Santa Monica has led many discussions surrounding how it can better support its cyclists and encourage cycling as a safe means of transportation, but like all L.A. County cities, there is still much work to be done.

I’ve been thinking a lot about questions surrounding this topic in Santa Monica. Where is cycling traffic centralized? What are the bike accident hubs? What streets have the highest bike accident rates? Some of what I found was predictable, other findings were more surprising.  I look forward to hearing everyone’s thoughts!

Where are people cycling? 

To answer this question I mapped all the 2011-2012 LACBC bike count data (UCLA Bike Count Data Clearinghouse) to visualize intersection ridership volumes.  As can be seen below, there is a high density of bike traffic in Santa Monica’s downtown center, as well as a few of the corridors that feed into this area.

Los Angeles County Bicycle Coalition, Bike Infrastructure, BikeLA

LACBC Bike Count Volumes

The map below highlights that much of Santa Monica’s bicycle traffic is currently unsupported by the city’s 2010 bicycle network. (Though Santa Monica’s infrastructure has changed since 2010, this data was most readily available through the Metro GIS Data Portal. This is a study limitation; however, as the 2010 network still functions as the backbone to the city’s bike network, there is still valuable information to be gained from the analysis) Looking at these two maps, it appears the most number of cyclists would be benefited by looking to Santa Monica’s Downtown as well as the two corridors most used by cyclist, i.e., along Broadway and Main (I will refer to these sections as the Broadway and Main Corridors).

santa monica bike volume and bike infrastructure

Where are bicycle collisions happening?

All reported collision data for Santa Monica can be downloaded from Berkley’s Transportation Injury Mapping Database. Below is a bike collision density map of these collisions layered over the bike count volumes and street grid. As can be seen, bike traffic volumes and collusions seem to be densest around Downtown Santa Monica, followed by a small cluster just south of downtown along Main.  The Broadway corridor additionally has a medium level of collision density.

Bike, BikeLA

Bike Collision Density

To move this map from a city boundary level to street level, I organized collisions into two categories: those that occurred within an intersection and non-intersection collisions. I found that 42.3% of all reported accidents occurred within intersections–usually this is where the majority of accidents occur.

The collision data shows the following streets have the highest number of bike collisions within the Santa Monica boundary.

Santa Monica high bike collision streets

Top Bike Collision Streets

As can be seen below, the majority of high collision streets feed into Santa Monica’s Downtown.

santa monica high bike collision streets map

Figure 7 – Mapping High Bike Collision Streets

Though I took this project further, this is a pretty good summary of my initial steps. The full report can be seen here.

Safe riding!


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