Tag Archive for US Census Bureau

Guest Post: Deep data analysis reveals the real causes of LA bike collisions

The key to improving bike safety is understanding how and why collisions occur.

Which has been almost impossible to figure out here in Los Angeles, where no one was keeping track of such vital statistics until recently. Let alone analyzing them.

I tried digging the data out of the statewide SWITRS traffic collision database before giving up, as have others before and since.

Now long-time LA bike advocate Dennis Hindman has dug through data compiled by the Los Angeles Police Department to uncover the causes of collisions — at least as determined by LAPD traffic investigators — with surprising results.

And makes the commonsense suggestion bicycling infrastructure should be installed first where cyclists ride, and collisions occur. At least until we have a fully built-out bicycling network.

I’m sharing the results of Hindman’s investigation, with his permission.

It’s a must read for anyone who cares about bike safety, and ensuring that everyone who goes out on a bike ride comes back home in one piece.

……..

The Census Bureau’s American Community Survey data results from 2007 through 2013 have a doubling of commuting by bicycle from 0.6% to 1.2%. Los Angeles Police Department reported 1,335 bicycle collisions in 2007 and 2,413 in 2013. That’s a 81% increase. Although the bicycle collisions have significantly increased, the rate of collisions per total number of bicycle riders has no doubt fallen.

I did a totaling of type of collisions in the first 100 pages (about 500 collisions) of the 484 page 2013 bicycle collision report that mentions each collisions individually and found the reported collision type or primary factor in the collisions to be:

  • 220 broadside
  • 110 wrong side (usually got hit by driver turning right)
  • 146 Right of Way auto
  • 70 stop sign
  • 40 improper turn
  • 48 sideswipe
  • 30 head on
  • 22 rear end
  • 10 improper turn
  • 8 too close
  • 5 improper driving
  • 10 lane change
  • 29 unsafe speed (usually unclear when that refers to bicycle or motor vehicle)

I haven’t seen anything in the report that mentions hitting a parked car door. There are several reports about hitting a parked vehicle though. I’ll try to figure out how many times that occurred in the total. Its much less frequent than getting broadsided.

Right of Way auto and broadside I assume would mean a bicycle running a stop sign or running a red light and a motor vehicle that had the right-of-way hitting the bicycle. I have yet to see a collision report state ROW bicycle, although it occasionally mentions ROW pedestrian.

The report does mention collisions when a motor vehicle was making a right-turn as a bicycle was going straight. I’ll try to see how frequently that occurred in relation to all types of collisions. This also seems to be a small proportion compared to the number of broadsides.

A Los Angeles Department of Transportation bikeway traffic engineer recently stated that they do not do treatments for bicycles at intersections. The bike lanes are striped where there are no crossing points for motor vehicles such as driveways, freeway on and off ramps, and cross street intersections.

The MIT Media Lab made a great looking map of all the LAPD reported bicycle collisions for 2012:

http://youarehere.cc/p/bicycle-accidents/losangeles

When I look at that map it seems to me that the bulk of the LADOT resources for bicycling should be concentrated in the areas of the city where the bicycle collisions are densely packed together. That’s also where the most bicycling occurs. If there are few staff members and a very small budget, then why try to install bicycle improvements across the whole city at once. That dilutes the effect by spreading out the improvements so much that they don’t connect into a network of any sort and the quality of the infrastructure won’t be as good because the emphasis is on quantity.

……..

Hindman followed-up with a brief email providing a little additional information and clarification. 

When I mentioned 70 crashes involving a stop sign it should be stop sign or traffic signal. I’m getting better at understanding the abbreviations in the crash data and hopefully I can tabulate the primary collisions factors and collisions types for 2013. I counted 16 bicycle fatalities for 2013.* One pedestrian was killed by a bicycle rider in 2007 and in 2012, but none in 2013. Both of these pedestrians were in their 80’s.

Spot checking the MIT Media Lab results of 54 bicycle crashes for Van Nuys Blvd I noticed that any time the LAPD bicycle crash data mentions Van Nuys as the primary or secondary street it was counted by MIT as a crash on Van Nuys Blvd. I have to assume that all the street crashes mentioned were totaled the same way.

……..

*Editor’s note: My records show 18 bicycling fatalities in the City of Los Angeles in 2013. The discrepancy may be due to one rider killed in a train collision, and another who was walking his bike when he was hit by a car; it’s possible neither was classified as a bike collision in the LAPD stats. Two of the cyclists killed in 2013 died as a result of doorings.