Portuguese mainland road network safety performance indicator

Stepping away from traditional crash-based road safety measurements, several safety performance indicators (SPI) have been proposed in the past few years. SPI can incorporate quantitative and qualitative information on specific aspects that are known to have influence in the safety levels and, not only measure the influence of various safety interventions but also enable comparisons between different road systems. This paper presents the results of the application of a road network SPI to the entire Portuguese road network. This SPI aims at evaluating at the network level, if the connections between urban centres within a region are made by the adequate type of roads regarding generic safety criteria. To this end, the connections to be assessed were classified into pre-defined theoretical safety classes, based on the population of the connected urban centres. Then, the observed safety class of these connections was assessed according to the characteristics of their cross-section and associated road environment of the existing connection between the two urban centres. If the observed class is ensured by a road of higher or equal class than the pre-defined theoretical level in all its extension, the link is considered to be of the appropriate class. For each connection, the results of its evaluation are expressed as a binary value: 0 when the class is not appropriate; and 1 when it is appropriate. The evaluation results are weighted by the road length and aggregated by connection class and throughout the whole road network. The results show a satisfactory network configuration with an SPI of 94% connections with class equal to or higher than the adequate for the type of connection between urban centres they established. The above insights can help in the identification of potential operational inconsistencies that may require safety-related interventions and used for international benchmarks against existing SPI evaluations.