Abstract
According to the Swedish "General Guidelines for Planning Urban Traffic Networks" speed should not exceed 30 km/ h on local streets.This can be done by short driving distances and suitable street design. On local streets providing driving distances greater than 150 m., the 30 km/h reference speed can only be expected if the street is specially designed or aligned. The following three types of speed-reducing obstacles for a signposted speed limit of 30 km/h are described in the report: 1) humps with rounded or level upper surfaces; 2) lateral displacement of the carriageway-chicanes; 3) width restriction of the carriageway.