The relationship between traffic volume and road safety on the secondary road network

On motorways, congestion is a well-known traffic problem. On the secondary road network, the same problem arises when traffic volume increases and the driven speed decreases. At certain times of day, roads get congested and the number of interactions between road users increases. In general, higher traffic volumes and congestion affect road safety. But how and to what extent does this happen? This study aims to gain more insight into the relationship between traffic volume and road safety and is limited to road sections and intersections on 80 km/h roads in the Netherlands. The two most common types of intersections - roundabouts and signalised intersections - are discussed in the present study. A literature review is carried out to investigate the relationship between traffic volume and road safety on secondary rural roads (mainly 80 km/h distributor roads). From the literature review carried out in this study, the conclusion is drawn that the relationship between traffic volume and road safety has not been studied widely. Although crash prediction models include traffic volumes, studies on these models focus on how infrastructural characteristics of road sections or intersections influence road safety, rather than on how traffic volumes affect road safety. Therefore, only a limited number of studies on crash prediction models could be reviewed in this study. Insight into the effect of traffic volumes on different types of crashes is limited, as is the relationship between traffic volume, overtaking behaviour and road safety. Since related studies have not been conducted in the Netherlands, this relationship is explored using research carried out abroad. It is unknown if the relationships described there can directly be translated to the Dutch situation. This study designates different topics which could be studied in future research.