Study: Drivers more likely to be at fault in car vs. bike crashes

Pose the question of who is more likely to be reckless on the road, a driver or a cyclist, and you'll likely get a heated debate. Drivers who dislike sharing the road with cyclists will accuse them of blowing through stop signs and red lights, turning without signaling, and otherwise acting irresponsibly. Cyclists will usually respond that reckless drivers are far more common, and far more likely to cause injury.

A recent study by the Queensland University in Technology has sided with cyclists on the issue, saying drivers are more likely to be at fault in car vs. bicycle collisions that occur at intersections in Australia. Researchers also determined that certain factors were more likely to be associated with a collision or increase the odds of a serious injury.

In 63.6 percent of the car vs. bicycle crashes included in the analysis, the driver was at fault. Drivers were more likely to be at fault at crashes at intersections with stop or yield signs, which accounted for 40 percent of all incidents in the study. Rabbani Rash-ha Wahi, of the Queensland University of Technology's Centre for Accident Research and Road Safety, said the collisions might result from the driver or bicyclist having an obstructed view when entering the intersection.

"In most cases, the bicycle and motor vehicle were approaching each other at right angles and possibly collisions occur because drivers have difficulty with judging gap sizes and speed before deciding whether to enter from the minor road or perform a turning maneuver," said Wahi.

Cyclists were at fault in 36.3 percent of crashes. The most common factors contributing to a cyclist being at fault included inattention, inexperience with riding a bicycle, and failing to obey traffic signals.

Drivers and cyclists were equally as likely to be at fault in collisions that occurred at intersections with traffic signals. A large number of crashes occurred at this type of intersection, possibly because cyclists often did not have enough time to safely cross the intersection before crossing traffic received a green light.

The study also looked at how different factors affected the severity of a cyclist's injuries after a collision at an intersection. Cyclists were more likely to be severely injured if they were at fault at an intersection with a stop or yield sign. Speed limits only appeared to influence injury severity at this type of intersection, which Wahi said might reflect differences in intersections rather than the effect of speed limits.

Wet road surfaces and complex intersections were more likely to result in severe injuries after a collision. Crashes occurring at unsigned intersections in hilly areas also tended to be more severe.

"It may be that cyclists and drivers can't see each other until too late because of the crests and dips, or that they were traveling faster," said Wahi.

Risk of injury in a collision between a vehicle and bicycle was found to be highest for cyclists in the 40-59 age group. The study suggested that this could be a result of slower reaction times and greater frailty among older cyclists, but also an increased propensity for these cyclists to use faster racing bikes which could increase impact forces and reduce the time for either a driver or cyclist to take action before a collision.

The findings were recently published in the journal Transportation Research Record. Wahi looked 5,388 police-reported crashes in Queensland between 2002 to 2014 for the report.

Previous overseas studies have also suggested that drivers tend to shoulder more of the blame for collisions with bicyclists. In 2009, a study commissioned by the Department of Transport in the United Kingdom found that risky cycling was only to blame in 2 percent of collisions where a cyclist was seriously injured. A year later, an analysis of vehicle vs. cyclist crashes in Melbourne, Australia found that drivers were to blame in 87 percent of the incidents.

Research in the United States has been more likely to conclude that bicyclists are at fault in collisions, however. The Minnesota Department of Safety determined in 2009 that cyclists and drivers were equally likely to be at fault, while an analysis of collisions in San Diego County found that cyclists were to blame in 60 percent of incidents in 2012. However, a recent study commissioned by the Florida Department of Transportation found that 100 cyclists tracked for the research were compliant with traffic rules 88 percent of the time – slightly higher than the driver compliance rate of 85 percent.