With bike-sharing programs in more than 500 cities worldwide accounting for a combined fleet of over 500,000 bicycles, cars are increasingly sharing urban streets with bicycles.
When crashes between bikes and cars occur they are often particularly dangerous for the cyclist. In 2012 alone, 722 bicyclists were killed in crashes with motor vehicles– a 6 percent increase from 2011, according to US government statistics.
To better understand the cause of crashes between cars and bikes, psychological scientists Nadine Chaurand and Patricia Delhomme of The French Institute of Science and Technology for Transport looked at differences in how cyclists and drivers perceive traffic risks.
Using an online survey, Chaurand and Delhomme asked 336 cyclists and 92 drivers to rate how likely various car-bike traffic scenarios were to cause a crash. The scenarios also included interactions between only cars, only bikes, and a car and a bike. In each of the scenarios, one of the parties was committing a traffic violation, such as tailgating or going through a red light.
The researchers found that drivers and cyclists had several commonalities in their perceptions of risk. For example, variables previously shown to impact risk perception for drivers–such as driving experience or perceived driving skill–had an effect on cyclists as well. Both cyclists and drivers also perceived less risk when they imagined themselves, as opposed to another vehicle, as the one making a traffic violation.
The study also found key differences in risk perception that could have important implications for improving road safety for both cyclists and drivers.
For nearly every bike-car interaction cyclists saw their own traffic violations as being riskier than drivers did. Cyclists also saw bike-car interactions as posing the greatest crash risk. However, drivers perceived interactions with other cars, rather than bikes, as being the most likely to lead to a crash.
“The fact that car drivers perceived an interaction with a bike as less dangerous than cyclists did could imply that when in interaction with a bike, drivers are not as careful as they should be in avoiding a crash,” Chaurand and Delhomme write in the journal Accident Analysis and Prevention, “or at least less careful than cyclists are.”
The researchers caution that the less people perceive risk in a given situation the more likely they are to adopt risky behaviors–and the more likely they are to be involved in crashes.
Chaurand, N., Delhomme, P. (2013) Cyclists and drivers in road interactions: A comparison of perceived crash risk. Accident Analysis and Prevention. 10.1016/j.aap.2012.09.005