Within the framework of BKA phase 2 (Basiskwaliteit Autosnelwegen) a number of driving simulator experiments have been performed. These experiments studied the relationship between different design elements of a cross section and driving behaviour. The results indicate that younger as well as older drivers are capable of driving the 2.50 m/70 km/h variant without noticeable decrements in driving behaviour. An important prerequisite, however, is that the left as well as the right side-markings on the road are elevated. For a lane width of 2.75 m no conclusions could be drawn since no results on experiments with an elevated right side-marking were performed. An additional experiment was executed in order to be able to conclude whether safety on lanes with a width of 2.75 m is also dependent on right side-markings or not. In a simulator experiment 14 younger drivers (< 50 years old), and 15 older drivers (> 61 years old) drove on the far left lane of a 3-lane road. This left lane was 2.75 m wide and the speed limit was 90 km/h. All participants drove in three different conditions: 1) With elevated road markings on the left and right side; 2) With elevated road markings on only the left side; 3) Without any elevated road markings on either side. An elevated road marking is indicated with hearing a sound when the markings are crossed. In the case of an intermittent line marking (between lanes) the sound is only audible when ‘a marking’ is hit. Results: Drivers swerve less with elevated road side-markings on both sides of the lane. Time-to-Line-Crossings (TLC) become smaller toward the right side of the lane when an elevated road marking is placed on the left side of the road. The time that drivers cross the markings on the right side of the road is longer when no elevated markings are placed on the right side (or when only on the left side an elevated marking is placed, or no elevated markings on both sides). Towards the left side marking (elevated in two of the three conditions) no effects were found. However, the improved driving behaviour that drivers reveal when elevated markings are in place leads to more effortful steering (higher frequency steering actions) and a higher subjective workload. Younger and older drivers differ in terms of a number of variables. Older drivers have smaller TLCs toward the right side markings and older drivers have a larger occurrence of smaller TLC values (1 second or less) than younger drivers. For the 2.75 m/90 km/h variant are elevated side markings in general preferable for both younger and older drivers in comparison to no elevated road markings. This improvement is however very limited and in the relation to traffic safety it is debatable to omit elevated road markings under these conditions. (Author/publisher)
Samenvatting