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CAN UBIQUITOUS RAMP METERING ELIMINATE MOTORWAY CONGESTION? Professor Markos Papageorgiou Dynamic Systems and Simulation Laboratory Technical University of Crete 73100 Chania, Greece [log in to unmask] http://www.dssl.tuc.gr 14:30 on Friday 19 April Room 610 Centre for Transport Studies Department of Civil and Environmental Engineering Imperial College of Science Technology and Medicine London SW7 2BU Travel directions at: http://www.cts.cv.ic.ac.uk Abstract Urban and interurban motorways had been originally conceived so as to provide virtually unlimited mobility to road users. The on-going dramatic expansion of car-ownership, however, has lead to the daily appearance of long recurrent and nonrecurrent motorway congestions around the world. Ironically, recurrent congestions of many kilometers in length reduce substantially the available infrastructure capacity during rush hours, i.e. at the time this capacity is most urgently needed, causing delays, increased environmental pollution, and reduced traffic safety. Similar effects are observed in the frequent case of nonrecurrent congestions caused by incidents, road works, etc. It is meanwhile broadly recognized that the mere infrastructure expansion cannot provide a complete solution to these problems due to economic and environmental reasons, or, in metropolitan areas, simply due to lack of space. The traffic situation on today's motorways resembles very much to the one in urban road networks prior to the introduction of traffic lights: blocked links, chaotic intersections, reduced safety. Clearly, the passage from chaotic to optimal traffic conditions is only possible if today's "spontaneous" use of the motorway infrastructure is replaced by suitable control actions aiming at the benefit of all users. Ramp metering is the most efficient means to this end, whereby short delays at on-ramps and motorway-to-motorway intersections is the (low) price to pay for capacity flow on the motorway itself, leading to substantial savings for each individual road user. The presentation will first explain, based on simple, mathematically sound examples, the reasons why ramp metering may lead to a substantial amelioration of traffic conditions in motorway networks. Some selected ramp metering algorithms will be presented next, based on traffic-responsive regulators and modern sophisticated nonlinear optimal control schemes. The presentation will include a selection of interesting field results and comparative evaluation investigations. Finally, a simulation example of large-scale nonlinear optimal ramp metering will be presented to demonstrate the high amelioration potential of suitably designed ramp metering control measures. -- John Polak Head of Transport Studies Department of Civil and Environmental Engineering Imperial College of Science Technology and Medicine London SW7 2BU T: +44-(0)20-7594-6089 F: +44-(0)20-7594-6102 http://www.cts.cv.ic.ac.uk