Crashes in Sweden taken from Folksam in-depth studies were used to show how crash severity depends on various road environments. Crash severity was shown for various speed limits, crash types and road surface friction. Data used were from 422 frontal vehicle crashes in Sweden with recorded crash pulses. The findings of the current study showed that the average change of velocity was 4.6 ± 4.1 km/h higher on roads with a 90 km/h speed limit than on roads with a 70 km/h speed limit. The corresponding difference between 90 km/h and 50 km/h speed limit was 7 ± 5.9 km/h. In single vehicle crashes into guardrails, average change of velocity was 6.6 ± 4.1 km/h lower than into ditches, stones and rocks. The corresponding difference for average mean acceleration was 1.2 ± 0.8g. Two vehicle crashes on rural and urban roads with oncoming vehicles, which had an average change of velocity of 31.8 km/h and an average mean acceleration of 8.6g, constituted the crash type with the highest crash severity. There was a significant increase in crash severity for single vehicle crashes with respect to increasing surface friction. This study shows that the average impact severity of crashes depends not only on the struck object itself, but also on the traffic environment in which the crash occurs. In the development of new safety technologies, real-world crash severity data are valuable as input in attempts to predict the safety effect of these systems in various road traffic designs. (Author/publisher)
Abstract