Could new road design at intersections lead to more bicycle traffic safety?
The traffic situation at intersections is an important indicator for cycling safety assessments. As statistics by the German Bicycle Club (ADFC) or the “cycling city” of Muenster (DE) reveal, more than 60 percent of inner city bicycle accidents are happening at intersections. To learn more about critical or even dangerous situations, near interactions and road design are evaluated as part of the BITS project to learn more about cycling safety.
Because of safety reasons two roundabouts at the main road in Damwald (Province of Friesland) in the Netherlands were changed into intersections in 2018. The plan was to decrease the speed levels of the traffic participants to increase the perceived safety feeling. Nonetheless, questionings among citizens revealed that the shared space concept of the new intersection at Haadwei – Foarwei has led to uncertainty regarding the right of way and more accidents. Further speed limitations are discussed.
As part of the BITS project smart cameras were already demonstrated earlier in the Province of Antwerp in Belgium to see how the road safety can be improved at an intersection. The University of Oldenburg, partner in the BITS project, has now made some further analysis, using data from similar smart camera technology which was tested at the Province of Friesland and in the City of Zwolle in the Netherlands. The data sets were delivered by Mobycon, which used Miovision cameras and the analysis by Microtraffic.
According to the evaluation results of the BITS project the highest amount of near interactions between vehicles and cyclists are happening especially on the north-south axis when vehicles driving through the intersection. There is a higher frequency of near interactions in the afternoon compared to other times of the day. The average speed of the vehicles is about 18 km/h what is comparatively high.
Critical situations at Haadwei and Thiedamawei in Damwald, Province of Friesland (Netherlands). Source: University of Oldenburg (ArcGis)
The results were compared to an intersection in Zwolle (Province of Overijssel, Netherlands) which has a very traditional Dutch road design. The evaluation of the intersection at Assendorperstraat/Luttenbergstraat shows that more than 80 percent of all critical situations are happening when vehicles turning left. There is also a higher frequency of critical situations in the afternoon. Although the average speed levels of the vehicles at Zwolle are lower compared to Damwald (below 15 km/h) many situations are much more critical. This is because the time to collision is in many cases lower what means that the vehicles and the cyclists tend to be approaching each other much more close when a near interaction is happening. According to the calculated numbers (Speed/Time to collision) the traditional Zwolle intersection is more critical compared to the two recently rebuild intersections in Friesland.
More than 80 percent of all near interactions at the intersection in Zwolle (Netherlands) are happening when vehicles are turning to the left to Luttenbergstraat. Source: Google Maps.
This article was written by Johannes Schering (University of Oldenburg) and Ronald Jorna (project manager of BITS).