ALINEA: a local feedback control law for on-ramp metering; a real-life study

A detailed investigation of the performance and effectiveness of strategies for motorway congestion reduction involving metering and control on motorway access ramps showed that significant improvements in traffic conditions have been obtained. This improvement is a function of the strategy tested. The best tested control strategy was found to be ALINEA, which was developed on the basis of classical control theory methods and which was the only strategy using feedback in a systematic way. Compared to beaconing, ALINEA leads to an increase of 3% with respect to the number of vehicles served, a decrease of 55% with respect to the time spent in congestion, and a decrease of 19% with respect to the mean travel time. ALINEA also proved superior in terms of the time during which the control override was active. Furthermore, this strategy diverts fewer vehicles than the other tested strategies. In fact, ALINEA was found to be a simple, efficient strategy which could be generalized in a coordinated ramp control scheme including the whole Boulevard Peripherique of Paris