Traffic models are being used in the Netherlands, albeit sparsely, to calculate bicycle networks. To this purpose adaptations of car models are sometimes used, or multimodal traffic models like Questor, Omnitrans or Trips. If necessary supplemented by the specific bicycle model Quavadis. Existing models all assume the cyclist to neatly stay in his own lane or path. But in real life cyclists swerve to avoid kerbs, bollards, traffic signs and other objects. They are overtaken by cars, but they themselves overtake slow-driving cars.
David Carrignon of the English firm of Colin Buchanan has attempted to catch the unpredictable behaviour of cyclists in a model. To that end he used the microscopic traffic model VISSIM. Currently this is mainly used to simulate traffic flow at street level by cars. Even though this was merely a first attempt, Carrignon is pleased with the result anyway. One of the conclusions is that when car traffic is congested, there is often room left to be used by cyclists. At least as long as the percentage of cyclists does not exceed 10 per cent.
The model does need additional calibration, according to Carrignon: ‘But it clearly demonstrates that bicycles and other two-wheelers are the new stakeholders where modelling traffic movements is concerned.’