Traffic congestion phenomena when motorway meets urban road network

The massive demand for road transportation will cause traffic congestion. This issue is especially severe when the motorway transitions to the urban road network. In view of the characteristics of the connection between urban road networks and motorway import and export, and intending to increasing the utilization rate of roads, alleviating road traffic congestion, and reducing motor vehicle pollutant emissions, this paper evaluated the effects of speed limit reduction in an area of Budapest, Hungary. The evaluation is based on an integrated model that combines the microscopic traffic simulation model VISSIM with the emission model COPERT. By applying the variable speed limit system, a reasonable speed limit value is formulated for the upstream road section of the congested section according to the traffic performance measured at the congested area. The results show a considerable reduction in pollutant emissions and traffic delays.