One of the key parameters, which determine the quality of service provided to the users of a tramway system, is travel time. The duration of travel and therefore the resulting commercial speed depend on the type of tram corridors, the length per corridor type, the distance between successive stops and the priority given to the tram at road and pedestrian crossings controlled by traffic lights. This paper focuses on the investigation of the impact of the green wave implementation in the signalling system of a tramway line. In this framework a) the different signalling systems adopted in tramway networks all over the world are described as well their impact on travel duration is analysed and compared b) the impact of giving priority to tram at traffic lights, on its commercial speed and for different scenarios of corridor typology, is examined, using empirical mathematical formula c) moreover, the recent implementation of the green wave policy in Athens' tramway system is examined and its impact on travel duration is evaluated, based both on in situ collected data and on international standards. According to the results of this work, a) if priority is given to the tram at traffic lights then the duration of travel can be reduced by 5%–35 %, b) Athens tram system has achieved reduction of travel time up to 19% regarding the different track sections of the network c) further reduction in travel times in Athens tram system can be achieved by additional interventions, regarding the signalling system, the type and the protection of corridors and the distance between stops.

tram signalling system, Athens tramway, green wave; commercial speed