Assessment of Socioeconomic Congestion Costs Caused by Severe Accidents on Major Roads

Assessment of Socioeconomic Congestion Costs Caused by Severe Accidents on Major Roads


H A Sørensen, Danish Road Directorate, DK; M Sdun, COWI A/S, DK


Serious accidents and incidents lead to socioeconomic impact other than the accidents cost themselves. To monitor the costs and target corrective steps, a model to estimate the socioeconomic costs of incidents and accidents have been developed.


Through the past 20 years, traffic on Danish roads has increased by approx. 70 %, particularly in and around Copenhagen and other larger cities, causing congestion and considerable delays during rush hours. Calculations have shown that in the metropolitan area of Copenhagen, congestions incur extra time costs of a total of EUR 750 million, annually. Therefore, the road authorities have put extra attention on identifying the causes for delays. One finding is that during the rush hour, the traffic circulation is very sensitive and even minor single incidents on the roads can cause instant congestion. As serious accidents are frequent and time consuming incidents, the Danish Road Directorate carries out a project focusing on the congestion costs caused by these accidents.

A main task therefore is to elaborate a model which can handle accident cost in a new way compared to the traditional assessment within traffic planning where road accidents costs, which normally are used within the cost/benefit comparison of e.g. black-spot analysis or the elaborating of traffic safety plans, have been based on an estimate of resource costs such as medical costs, vehicle repair cost, administrative costs including the estimate of cost of lost output of those killed or injured in road accidents.

First, the project will elaborate an overview and quantify the amount of waiting time, extra travel time and extra kilometres due to detours caused by severe accidents. The results are expected to be used as background for decisions on prioritization of mitigation measures. For this purpose a model based on observed accidents and traffic amounts calibrated with real time registration of travel time will be elaborated. The real time registrations used to calibrate the model will be combination of data from road side system for travel time measurements and GPS data from a fleet of trucks logging their GPS positions every 5th second.

Second, the project will estimate how the extra travel time and kilometres can be quantified in terms of socioeconomic costs.

A possible outcome could be a policy and action plan for minimising the impact on e.g. extra travel time caused by road accidents. The actions could be all from campaigns with the goal of better cooperation between police and rescue workers, to campaigns towards the daily users of the road and thereby state how to behave when a accidents occurs to including these costs in the cost-benefit analyses of accident reducing measures. Thereby, both the accident costs and the avoided congestion cost will form part of the evaluation of the impact of such measures.


Association for European Transport