The objective of this study was to evaluate whether a simple model for a safe road transport system, which includes the interaction between human beings, vehicles and the infrastructure could be used to optimise the components of the system.

Real-life crashes with a fatal outcome were classified according to the vehicle’s active and passive safety system. For each crash, classification was also made of the infrastructure with EuroRAP, and human behaviour in terms of speeding, seat belt use and driving under the influence of alcohol. The ideal situation was simulated, when all the above factors were altered to what is expected in a safe system.

All fatal crashes where a car occupant was killed that had occurred in Sweden during 2004 were included:​ in all 215 crashes with 248 fatalities. The data was collected through the in-depth fatal crash data collection from the Swedish Road Administration.

It was possible to show both the model as well as where the highest potential could be found in a systems perspective. The model could handle more than 90% of the crashes. In general, it was found that impact severity was higher than the expected crash protection of a modern and safe vehicle, even when the occupants were belted and not speeding. The most common and weakest part of the system was therefore the road in the form of speed infrastructure relations. The human criteria were fulfilled in 28% of single collisions and in 80% of side impacts. A safe car, according to the given criteria, would have influenced the outcome in 41% of the accidents on 50km/h- and 70km/h-roads, and 32% on 90km/h-roads.

The future road transport system must be more compatible and more effective in limiting the consequences of road crashes. When prioritising preventive measures, the model might be an instrument to support that process.