Crash Patterns in Western Australia

Examination of crash patterns is one way of identifying key factors on which focus should be directed for improving road safety. This paper has researched the current status of a number of selected crash patterns in Western Australia and compared this status where possible with that existing 10 or 20 years ago. The crash patterns examined are road type crash risks, speed, fatigue, night-time, severity and collision types. It is considered that the results should be useful not only to Western Australia but also to road safety agencies elsewhere.

The paper provides quantitative information on crash risks of various levels of road design ranging from unsealed country roads to freeways using a large sample of some 100 000 crashes. Quantitative estimates based on surrogate measures show that both speed and fatigue are major contributing factors in crash occurrence. In taking traffic into account it is shown that both the risk and severity of crashes is higher at night than daytime particularly in the open road environment.

In addition to numbers and risk values, patterns are also expressed in terms of crash costs. Crash costs are proposed and demonstrated as a method for the optimum allocation of resources directed towards road safety improvement.