A new type of road marking on residential roads outside the built-up area is emerging; a marked driving strip for motor vehicles. The border marking is situated several decimetres from the edge of the road surface. By this means there exists an outside edge strip between the marking and the road surface edge that could be used by cyclists (and the occasional pedestrian). Between the outside edge strips on either side of the carriageway, there exists a driving strip without an axis line. The driving strip aims to: (i) lower the driving speeds by means of a visual narrowing of the carriageway; (ii) provide the cyclists their own safe place on the carriageway by marking the driving strip; and (iii) cause less damage by motor vehicles to the edges of the carriageway and shoulder. The question is whether the marked driving strip achieves these positive aims. An answer to this question was sought by means of inspections, observations, and measurements on a number of roads, with and without these driving strips. Outside edge strips occur on narrower roads than where the Dutch Centre for Research and Contract Standardization and Traffic Engineering CROW proposed them. CROW maintains that outside edge strips on both sides of the road should have a minimum width of 1.25 metres, and that the road itself should be at least 5.5 metres wide. Almost all the roads found and used in this study are narrower. All the outside edge strips found were also narrower. For the purposes of this study, the different edge strip widths were subdivided into three classes: narrower than 80 centimetres, 80-95 centimetres, and broader than 95 centimetres. In fact, all three classes consist of ‘narrow’ edge strips. Speed measurements did not show that cars drove considerably slower on roads with outside edge strips than on roads without them. The speed differences found were small and showed an unsystematic, unclear pattern. The space between an overtaking motor vehicle and a cyclist is at its smallest when no outside edge strips have been provided. Only a small percentage of cyclists cycle outside the edge strips; a maximum of c.11% in the case of those cycling alone. On roads with broad outside edge strips, and to a lesser extent on roads with narrow edge strips, the cyclists swerve less when being overtaken, than on roads without edge strips. The narrower the edge strip the more the cyclists swerve to the right. The narrow edge strips would appear to offer the cyclists their own place less than broader edge strips. In the most cases where the shoulder was used, there were one or more agricultural vehicles or lorries involved. In the most cases where vehicle were observed using the shoulder while swerving, were on roads without outside edge strips. The roads, however, also have a narrower hardened road surface than the roads that do have edge strips. Edge strips would appear not to result in motor vehicles driving closer to the middle of the road. The high speed limit (80 km/h) and the sometimes even higher measured driving speeds of cars and lorries, and the slow speeds of cyclists, lead to great differences in speed and mass. This is in conflict with the principles of ‘sustainably safe’. Even if the speed limit was to be reduced from 80 km/h to 60 km/h, the expected differences in speed are still great. The new type appears to have only small effects. Based on the data in this study, it has not become clear that the introduction of outside edge strips, on its own, is a sufficiently effective means of achieving the goals aimed at. (A)
Abstract