To investigate the effect for the road users during driving in darkness of removing the centre line and having guide posts that in principle are not visible in darkness, respectively, a driving simulator study has been carried out. The two above mentioned road types, i.e. an 8 m wide road with/without guide posts and with posted speed limit 90 km/h and a 6 m wide road with/without centre line and with posted speed limit 70 km/h, respectively, have been studied in two separate driving tests.

A total of 30 subjects have driven both road types during darkness under conditions corresponding to both dry and wet road surface, alternatively new and worn road markings, i.e. with road markings that are visible on a long distance or only on a short distance. The study showed among other things that when the road markings fulfil the requirements for visibility given in the regulations the speed is only slightly influenced by whether there are guide posts or not. On the other hand, if the visibility of the road markings is poor one uses the visual guidance from the guide posts to be able to drive at a higher speed.