Different effects of bypass solutions have been analysed at the request of the National Swedish Road Administration. The project was based on an inventory of existing bypass solutions and a description of bypasses constructed during the period of 1970-1989. Different effects on traffic have been analysed for the bypasses constructed in connection to built-up areas with 2000-10000 inhabitants concerning road safety, traffic on the through road before and after the construction of the bypass, travel time effects, change in vehicle costs and exhaust emissions, as well as the economy to society. The accident rate of the road systems was reduced when the bypasses were constructed, but the severity of the accidents increased. The greatest road safety effects were obtained when the bypass was a new road construction outside the town centre compared with a bypass which only consists of a new road past the town centre. Among the traffic effects, it was observed that the travel time savings of the traffic moved from the through road to the bypass are the dominating effect. To describe qualitative effects, a sample of residents in nine municipalities with no bypass and nine municipalities where bypasses have been constructed at the end of the 1980's, were asked about the situation on the through road by means of a questionnaire. They also had to judge the effect of a bypass or the obtained bypass, respectively. It can be seen that the through road is the greatest traffic and traffic safety problem independent of whether or not a bypass is constructed. The reduction of heavy vehicle traffic and decreased discomfort from noise, exhaust and vibrations from traffic were stated as the greatest effects. The paper consists of this abstract.
Abstract