Effects of a robust roads network on bicycle traffic; Results obtained from a microsimulation model. The traffic flow on the Dutch main road network is problematic due to intensive use and near stagnant capacity. As a result the accessibility of the economic centres is still under heavy pressure. In 2008, the Royal Dutch Touring Club ANWB made public its vision on the road network. This vision, known as the Robust roads network is intended to be the answer to the increasing vulnerability of the present road network for disturbances of the traffic flow. SWOV, together with ANWB, carried out a pilot study into the safety effects of a robust roads network. This pilot study found relatively small differences between the Sustainable Safety vision and the Robust roads network, for both traffic flow and road safety. It seems feasible to integrate the two visions into a system that offers a larger traffic flow and at the same time provides optimal safety. The pilot study did not yet answer the question of which effects a robust roads network would have on bicycle traffic. At the same time, however, motorized through traffic will (incidentally) make more use of the secondary roads network and at those locations interfere with bicycle traffic. The present report, therefore, has attempted to find answers to the following questions: 1. Which effects on road safety are to be expected when robust roads networks are introduced? 2. Can these effects be quantified? 3. Which measures can be taken to prevent possible adverse consequences? The effects of a robust roads network on bicycle traffic has been investigated with the microsimulation model S-Paramics. In this model a road network was simulated in which part of the car traffic made use of the secondary roads after an incident had occurred on the main roads network. An intersecting bicycle path was simulated at one of the secondary roads. This gives an impression of the hindrance (flow, safety) that bicycle traffic can experience at intersections when the car traffic uses the secondary roads as an alternative. The microsimulation model does not (yet) have the possibility of simulating the hindrance cyclists may experience at road sections. The present study has established that the greatest effects on traffic flow may be observed at intersections with priority for car traffic. At this type of intersection, bicycle traffic flow is obstructed when car traffic uses secondary roads as an alternative. There are no adverse road safety effects at this intersection type. Adverse safety effects do indeed occur at intersections with priority for cyclists. This type of intersection enables good traffic flow for cyclists despite the increase in car traffic (due to the incident on the motorway). The intersection with traffic light control achieves good flow as well as safety for both bicycle and car. It must be noted, however, that the simulation model underestimates the dangers at this intersection type, as, other than in reality, the model does not allow for going through a red light.
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