Study identifies factors associated with severe injuries in cyclists

A study carried out by researchers in the USA has identified a number of factors which are strongly associated with cyclists receiving severe injuries in collisions. The most dangerous factor is motor vehicle speed. When cyclists collide with vehicles traveling at over 50 mph (80 kph) they are more than 16 times more likely to die from their injuries, when the speed is over 30 mph (48 kph) the risk is doubled. When the vehicle’s speed is less than 20 mph (32 kph) there is a greatly reduced risk of harm to the cyclist. This clearly shows the importance of avoiding high-speed traffic when cycling. Other factors which more than double the risk of death include poor weather, dark streets, morning rush hour, head-on collisions, a truck being involved, alcohol consumption by either the driver or the cyclist and the cyclist being over 55 years old.

It is also interesting to note that when the cyclist is at fault they are more likely to be severely injured than when the driver is at fault.


This research explores the factors contributing to the injury severity of bicyclists in bicycle-motor vehicle accidents using a multinomial logit model. The model predicts the probability of four injury severity outcomes: fatal, incapacitating, non-incapacitating, and possible or no injury. The analysis is based on police-reported accident data between 1997 and 2002 from North Carolina, USA. The results show several factors which more than double the probability of a bicyclist suffering a fatal injury in an accident, all other things being kept constant. Notably, inclement weather, darkness with no streetlights, a.m. peak (06:00 a.m. to 09:59 a.m.), head-on collision, speeding-involved, vehicle speeds above 48.3 km/h (30 mph), truck involved, intoxicated driver, bicyclist age 55 or over, and intoxicated bicyclist. The largest effect is caused when estimated vehicle speed prior to impact is greater than 80.5 km/h (50 mph), where the probability of fatal injury increases more than 16-fold. Speed also shows a threshold effect at 32.2 km/h (20 mph), which supports the commonly used 30 km/h speed limit in residential neighborhoods. The results also imply that bicyclist fault is more closely correlated with greater bicyclist injury severity than driver fault.


Bicyclist injury severities in bicycle-motor vehicle accidents
Kim, Joon-Ki (Washington University in St. Louis, Department of Civil Engineering, One Brookings Drive, St. Louis, MO 63130-4899, United States); Kim, Sungyop; Ulfarsson, Gudmundur F.; Porrello, Luis A. Source: Accident Analysis and Prevention, v 39, n 2, p 238-251, March 2007

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