Cyclists at Fault in Most Car vs Bike Collisions

Cyclists at Fault in Most Car vs Bike Collisions

While cycling is being promoted as safe, clean and energy efficient,  it is an everyday occurrence to see cyclists running stop signs, and even red lights –  seemingly as if laws do not apply to them. While the same is true of cars, the issue appears to be far more significant for cyclists.

Rather than rely on anecdotal observation I went to the source to find out the real story. Thanks to the California Highway Patrol I was able to secure data for the years 2011-2012 for the entire state. Previously I had reported on accident figures for the city of San Rafael, but the numbers were arguably too small to be statistically significant.

Framing the Data

(1) The data only covers instances of collisions between vehicles and bikes – so it is vitally important to remember that it omits all vehicle vs vehicle collisions. I do not have this information, but I would speculate that there were far more vehicle vs. vehicle collisions than there were vehicle vs. bike collisions.

(2) The data only covers instances of collisions where there was a stop sign violation, or a red light violation

(3) The data combines the years 2011-2012 in order to generate more statistically significant conclusions. This is the most recently available data as of the date of publication (24th April 2014).

(4) The CHP informed me that in general there has been a trend of increasing vehicle fault collisions over the past few years caused by texting and smart phone related distractions.

(5) The data does not cover any collisions where there was not a stop sign or a red light violation.

Cyclists Major Cause of Car vs Bike Stop Sign Collisions in California

Here is the California statewide data for collisions between bikes and vehicles in the years 2011 – 2012 following a stop sign violation. This is the latest available reporting data as the CHP aggregates data from many different jurisdictions across California into common categories:

Screen Shot 2014-04-24 at 9.57.39 AM

Vehicle at Fault in Stop Sign Violation Leading to Bicycle vs Car Collision, California 2011-2012

At Fault 2011 2012 Total Percentage Deaths
Bike 435 485 920 59.9% 9
Vehicle 191 208 399 26.0% 4
Unknown, Hit & Run 106 110 216 14.1% 4
Pedestrian 0 2 2 0.1% 0

Assumptions

  • We might assume that a substantial proportion of the unknown faults were caused by a similar split to that of known faults.
  • We might assume that for hit and run incidents the vehicle was more likely at fault   – since after a collision it is more likely that the cyclist will be incapacitated.

Cyclists Major Cause of Car vs Bike Red Light Collisions in California

Reviewing red light violations in 2011-2012 in California leading to collisions between bicycles and cars a similar picture emerges:

At Fault 2011 2012 Total Percentage Deaths
Bike 435 485 920 59.9% 9
Vehicle 191 208 399 26.0% 4
Unknown, Hit & Run 106 110 216 14.1% 4
Pedestrian 0 2 2 0.1% 0
Red Light Collisions

Vehicle at Fault in Red Light Violation Leading to Bicycle vs Car Collision, California 2011-2012

 

Conclusions

We cannot say that cyclists are a major cause of collisions – as the data does not include all collisions – and it’s highly likely that the total number of vehicle vs. vehicle collisions far eclipses that of bikes. What we can say from this data, is that in the event of a collision between a vehicle and a bike at a stop sign, where there was a stop sign violation, it is statistically more likely that the cyclist was at fault.

California appears to have a significant issue with bicycles not stopping at stop signs or red lights – with this leading to collisions, often most unfortunately, causing the injury and in rarer cases the death of the rider and not the driver. Of the 17 red light violation deaths, 9 were where the cyclist was at fault; of the 9 stop sign violation deaths 8 were where the cyclist was at fault.

What’s needed is a public safety training – made accessible in all languages. In Britain in the 1970s there were widespread public safety films explaining:

– how to turn left across traffic (in Britain of course it is how to turn right)

– that as a cyclist you are a vehicle; you cannot switch between traveling as a pedestrian would on the sidewalk and pedestrian crossings then back to a vehicle as it suits you. If there is a bike line you can and should use it, otherwise you should act as a car (with the exception of using freeways where bicycles cannot legally be used).

What would also be worthwhile is that the Police ensure that stop signs and red lights are adhered to by vehicles and cyclists alike. Ultimately we want fewer collisions and most importantly fewer deaths. The data speaks to how efforts should be focused to address this.

Raw Data

Interested in the data behind this report? You can download the Excel spreadsheet provided by the CHP here.

  • NoeValleyJim

    If you ignore the number one cause of auto vs. bicycle collisions, you might get this data. Why did you ignore dooring and overtaking as causes of accident?

    Other studies get far different results than you did:

    http://pubsindex.trb.org/view.aspx?id=469382

  • Prairie Boy

    It’s curious that Idaho’s rolling stop legislation correlated to a 14.5% decrease in bike/motorist collisions. (Jason Megg)