Some aspects of speed-flow relations on German motorways

Abstract

Based on long-term speed measurements within the "Exhaust Gas Large-Scale Test 1985" (Abgas-Grossversuch) at about 30 points of the German motorway network, speed-flow curves were derived and analysed. All curves are related to road sections of 2 or 3 lanes with only low incline and without speed limits because there exists no general speed limit for passenger cars on German motorways, only a recommended speed of 130 km/h (81 mph). The study was sponsored by the Federal Minister of Transport and was to update the curves of earlier investigations which were no longer relevant because of general changes of many parameters of traffic and traffic behaviour.