The ‘Directive on Special Road Markings’ has allowed red colouring of cycle lanes in Switzerland for several years. However, the directive only permits colouring in certain cases. According to the directive, the marking may only be applied ‘to main and priority-entitled side streets with high traffic volumes and only in branching and single-lane areas where, due to traffic and visibility conditions, there is an increased risk that motorised traffic will disregard the right of way of cyclists when crossing the cycle lane. Markings are not permitted outside of cycle lanes.’

In many places, red colouring of bicycle infrastructure is already being used beyond the permissible scope in order to visually emphasise the bicycle traffic routing. Internationally, bicycle traffic facilities are sometimes fully coloured (regardless of whether there is an increased risk). The city of Zurich is also interested in expanding the possibilities for marking bicycle infrastructure. The present study is to be accompanied by suitable monitoring so that insights can be gained into the effects of the measure. These are in turn to be incorporated into the further development of the nationwide regulations on such markings.