Factors affecting motorcyclists' injury severities: An empirical assessment using random parameters logit model with heterogeneity in means and variances.

Motorcycles constitute 61% of the total registered vehicles in Pakistan and there has been a 371% growth in motorcycles in the country from year 2005-2015. Motorcycle is an essential and popular mode of transportation in Pakistan, therefore, the present study estimated a random parameters logit model to investigate the factors influencing the motorcycle injury severity using motorcycle crash data of Rawalpindi city collected by the Provincial Emergency Response Service. No injury, minor injury, severe injury and fatal injury are used as four categories of motorcyclist injury severity levels to calibrate the model. Mainly the effects of speed limits, crash-specific factors, rider attributes, roadway characteristics, weather and socio-demographics factors are considered for motorcycle-injury severity analysis. It was revealed that probability of fatal/severe injury increases for crashes: involving middle-aged riders (25-50 years) and riders with no education, occurring on roads with posted speed limit of 70 kms per hour or higher, crashes involving a motorcycle and a heavy vehicle, involving collision of a motorcycle with a fixed object and occurring during dry weather conditions. Also, the probability of minor injury increases for crashes: occurring on divided streets and road segments with a posted speed limit of less than 50 kms per hour, involving Chinese brand motorcycles, involving registered motorcycles, and where at least one motorcycle and auto rickshaw is involved. The research findings suggest that besides measures to control/ reduce the risky motorcyclists behavior there is a need to lower speed limits on roads with a higher motorcycle proportion, separate motorcycles from heavy vehicles and removal of fixed objects from the roadside. Besides data limitations, results are expected to generate more discussion and interest in motorcycle safety in the country and can be used by the enforcement agencies to improve/ enhance the current state of motorcycle safety in the country.