Norway is at the top when it comes to road safety worldwide. Accident models and figures or functions that show the effects of traffic safety measures (impact factors) are important tools for improving traffic safety in the most efficient way. The program that the Swedish Road Administration uses to calculate the effects of traffic safety measures is called TS effect.
TØI has compared Norwegian accident models and impact factors with those developed in other countries. Technically, the models we use in Norway are top notch.
The first modern accident model in Norway came in 2002 and has since been updated several times. A new update is underway in 2023. The models can say something about the safety of the road network in general, but also for specific road elements such as intersections, curves and tunnels.
In recent years, the number of accidents and the number of people injured or killed in traffic have changed rapidly. The models then quickly become out of date and need continuous updating.
When it comes to the effects of road safety measures, these are increasingly indicated in the form of functions, not point estimates. This reflects the fact that the effects of many road safety measures vary systematically with other measures, something that is not captured by only stating a single figure for the effect of a measure. It is also desirable to distinguish as much as possible between effects on those killed, seriously injured and lightly injured.
These are the accident models reviewed in the report:
- Danish accident models and impact factors
- The Finnish TARVA system
- The PRACT models (European project)
- The EGRIS models (European project)
- Accident models in the Highway Safety Manual (USA)
- The IRAP system for classifying roads by safety
- Impact factors in the Crash Modification Clearinghouse (USA)
The report is financed by the Norwegian Public Roads Administration.
