Health Losses in Motorcycle Crashes - Injury Analysis of Crashes into Road Barriers and Evaluation of Antilock Braking Systems

Licentiate thesis, 2014

Motorcycles crashes are a growing road safety problem. While the traditional safety approach has focused on protective gear and rider education, with the Vision Zero approach, the designers of the road transport system are considered responsible for its design and operation. Motorcycles are intrinsically unstable vehicles: in the case of instability, the most likely consequence is that the rider is separated from the motorcycle. The only countermeasure to avoid health losses is then the rider’s protective gear. This issue has not been addressed in the past with a holistic approach. In this thesis, the integrated chain of events was used as a theoretical framework: the chain of events leading to a crash is no longer seen in separate blocks; it is rather a process in which one factor in the early stages of the chain can affect the following ones, thus creating the conditions for other countermeasures to be effective. This thesis is based on two papers aiming to: (1) understand whether the injury outcome in motorcycle crashes into road barriers can be reduced when the motorcyclist is in an upright position prior to collision and; (2) estimate the effectiveness of motorcycle Antilock Braking Systems (ABS) in reducing injury crashes in Sweden, Italy and Spain. Study 1 used interviews of 55 Swedish motorcyclists who sustained injuries in crashes into road barriers between 2005-2009. Each subject’s injury scores were converted to the Risk for Permanent Medical Impairment (RPMI) in three levels (1%, 5% and 10%). The analysis showed that the injury severity was lower in crashes in which the motorcyclists were in an upright position during the collision. The proportion of subjects with Injury Severity Score (ISS) 16+ was 24% lower in those crashes compared to those who slid into the barrier. In addition, the share of AIS 2+ and AIS 3+ injuries were 22% and 12% lower, respectively. The mean RPMI 10+ was 51% lower, although this result was not statistically significant. However, leg injuries were more common. Study 2 used police reports from Spain (2006-2009), Italy (2009) and Sweden (2003-2012). The same motorcycle models, with ABS (n=1596) and without (n=9104) were compared with an induced exposure approach; the calculations were carried out for each country separately. Crashes involving only scooters in the Italian and Spanish databases were further analyzed. The effectiveness of Motorcycle ABS in reducing injury crashes ranged from 24% in Italy to 29% in Spain and 34% in Sweden. The reductions in severe and fatal crashes were even greater, at 34% in Spain and 42% in Sweden. The overall reductions of crashes involving ABS-equipped scooters were similar. Based on these findings, it could be hypothesized that there are two different chains of events depending on whether the motorcycle is stable (i.e. ABS-equipped) or not, given the same boundary conditions. In other words, improved stability would prevent some crashes. However, some riders will go further in the chain of events. The crash would still be unavoidable, but more favorable conditions would result by crashing in an upright position, thus providing some injury mitigating effects. KEYWORDS: Motorcycle, Powered Two Wheelers, Crash, Injury, Health Loss, Safety, Stability, Road Barrier, Antilock Braking Systems