Within the framework of BkA phase 2 (Basiskwaliteit Autosnelwegen) a number of driving simulator experiments has been performed. These experiments studied the relation between different design elements of a cross section and driving behaviour. The overall research question was: What is the influence of different lane widths of a cross section on speed and driving behaviour in relation to other design aspects of the road? Where can we find possible turning points and what kind of compensating measures are important to reduce the consequences for traffic safety? A total of 6 experiments was carried out: (1) An experiment in which ‘elderly’ drove for a longer period of time over a narrow cross section, (2) a validation study of the driving simulator, (3) an experiment in which 15 different cross section variants were systematically compared with one reference variant, (4 en 5) two experiments in which the two ‘best’ cross section variants from the former experiment were tested in more detail on safety when drivers have to drive this type of road for a longer period of time, and (6) an experiment in which the effect of raised road markings were tested. This report gives an overview of the results of all these studies. An overview is provided of these 6 experiments on the basis of a schematic model and a brief summary of the different methods. After this, the possible effects of critical circumstances are discussed that were not taken into account in these 6 experiments, but could have consequences for the minimal cross section width. The best option is a cross section design in which the left lane is 2.75 m wide and the maximum speed limit is 90 km/h (depending on the width of the middle lane there is a overtaking prohibition for trucks). The distance to the crash barrier can be kept small. There are, however, compensating measures necessary to make sure that drivers actually do drive 90 km/h. Elevated road markings are not really necessary (although it can be very helpful for younger as well as elderly drivers). A second option would be a cross section design in which the left lane is 2.50 m wide and the maximum speed limit is 70 km/h. In this option also compensating measures are necessary to make sure that drivers keep the speed limit. But more importantly, elderly drivers benefit a lot by elevated road markings in this cross section design. The significance of these elevated road markings is in this design much bigger than in the first mentioned 2.75 m / 90 km/h variant. The inventory of critical circumstances shows that a number of quite daily circumstances exist that could effect the lane keeping behaviour in a negative way, and, consequently, may increase the minimal lane width to compensate for these effects. With how much can not be indicated without further study. (Author/publisher)
Samenvatting