The Intermittent Bus Lane System: Lisbon Demonstration Project

This article explains the concept of intermittent bus lanes (IBL) and describes a demonstration project of this innovative approach to achieving bus priority. An IBL is a road lane in which the status of each section changes according to the presence or not of a bus in its spatial domain. When a bus is approaching an IBL, the status of that lane is changed to bus lane and after the bus moves out, it opens again to general traffic. A real world 6-month demonstration of the IBL approach was carried out as a prototype in Lisbon under an agreement between the university that developed the concept, the municipality and the urban bus operator. The results obtained from the demonstration project shows an average increase of about 20% in bus commercial speed, with peak hour gains in the order of 50%, and with very limited impact on general traffic movements. Driver reaction towards the system was positive, with a good level of self-compliance. These findings, along with the low marginal cost of implementation, suggest that the IBL concept could improve the quality of bus service and increase productive efficiency in congested urban road sections where bus frequency is low or moderate.