The impact of spatial clustering of transport infrastructure on risk

The hypothesis has been formulated that spatial clustering of transport line infrastructures might generate higher risks in terms of higher probability of accidents and/or more severe consequences of accidents. The risk increase is assumed to be the result of interference between transport flows. No systematic research has been performed so far to test this hypothesis. This paper therefore presents the results of an empirical study on this subject based on accident data from the Netherlands. It is concluded that clustering of infrastructures has not caused a higher probability of accidents in the past. However, impacts of accidents in terms of the number of casualties are significantly more severe. This generates new discussions on the spatial planning of infrastructures on the one hand and the organisation of emergency response capabilities on the other.