Building a model for safety effects when travel modes change - it's complicated...

ViaStrada Director Glen Koorey presented on recent work to investigate the interaction of vehicle travel and crash risk, and to develop a model to test the safety implications of various mode-shift scenarios. 

While a simple model would just use relative casualty numbers and travel usage for each mode to get a basic comparison of risk, several other interacting and competing effects should also be factored in. These include changes in distances now travelled using new modes, additional “first/last mile” travel with new public transport trips, transport facility improvements that can increase the use and reduce the risk of different modes, vehicle occupancy rates for different modes, and the effects of congestion, speed limits, and various Safe System measures on crash severity. As you can see, it’s not so simple…

You can view Glen's full presentation here.