Modern town and traffic planning principles have failed to solve the safety problems on arterial roads in urban areas. In Sweden and probably in most other countries, a very high portion of the pedestrian and bicycle accidents in urban areas occur on arterial roads. Safety measures such as signalization pedestrian over- or underpasses have not been overcome. Walking and driving against red creates new types of risks where road-users and end up in unexpected conflicts where the probability of a successful avoidance an accident is low. Vehicle speeds on arterial roads are generally too high. This means that there is practically no interaction between vehicle-drivers on the arterial and intersecting road-users. For instance, it is a fact today, that almost no driver stops to let a pedestrian pass at a zebra-crossing. An important consequence of this is that vehicle-drivers on the arterial have a very low degree of attention paid to possible conflicts with intersecting road-users. This especially true for intersecting pedestrians and bicyclists. The results is severe accidents. A first experiment is carried out with an alternative regulation for intersections. In the city of Malmö (250.000 inhabitants) a non-signalizes four-way intersection is provided with speed-reducing mounds. A number of before- and after-studies have been carried out. A traffic conflicts technique, developed at the department, has been used to study the safety effects. The number of serious conflicts has dropped dramatically, especially those involving bicyclists and pedestrians. Vehicle speeds are low and very homogenized after the installation of the mounds. The implementation costs are less than a tenth of the cost for traffic signals. Besides, vehicle delays in this case are much lower due to the speed-reducing mounds than if traffic signals had been installed. The results are very promising and they are going to be followed up by larger studies on stretches of arterial roads where mounds are going to be installed to create a general speed-reduction. The basic hypothesis is that speed reduction can be used as an extremely safety-beneficial countermeasure for general use in urban areas. In principle, the ideal speed from a safety point of view van be decided on individually for each part road. This strategy is partly opposed to the conventional method of closing streets, making one-way streets, etc. Speed reduction will make it possible to keep all streets as two-way streets which will minimise trip-length and will, for instance, make orientation much more easy than if streets are closed, etc.A speed reduction of 10-15 kilometres per hours is probably much less dramatic than the successful reduction of speeds in rural roads in most countries during the last five to ten years. (A)
Abstract