Influence of crash pulse characteristics on injury risk in frontal impacts based on real-life crashes

In single-vehicle car crashes with roadside objects, one way to achieve low acceleration is to allow long duration by making objects more flexible. There is a lack of knowledge regarding the influence of long pulse duration on injury risk. The objectives were to study the influence of crash pulse characteristics on injury risk in frontal impacts and to study the correlation of these crash pulse characteristics, especially including crash pulse duration. Furthermore, the objective was to study crash pulse characteristics in crashes with various types of guardrails.

To study the influence of crash pulse duration on injury risk, data from 448 real-life frontal collisions with recorded crash pulses were used and a subgroup of 37 guardrail crashes was analyzed. The inclusion criteria were repair cost and impact angle. Five hundred seventy-eight restrained occupants were included. Injury risk, correlation, and sensitivity analyses were made for the various crash pulse characteristics.

It was found that the duration has a limited influence on injury risk. Change of velocity and mean and peak acceleration were found to influence injury risk and they were also well correlated. The correlation between mean acceleration and pulse duration was low. Crashes into cable barriers were found to have lower acceleration than crashes into w-beam and concrete barriers. The difference in mean acceleration between the most and less severe barrier crash was smallest in crashes with cable barriers.

Long duration of the crash pulse does not lead to high injury risk as long as the mean and peak acceleration are low. In the design of cars and roadside objects the main design criteria should be acceleration and not delta V, due to the findings that long duration could be handled.