Operation Regimes and Slower-is-Faster-Effect in the Control of Traffic Intersections
The efficiency of traffic flows in urban areas is known to crucially depend on signal operation. Here, elements of signal control are discussed, based on the minimization of overall travel times or vehicle queues. Interestingly, we find different operatio
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Abstract The efficiency of traffic flows in urban areas is known to crucially depend on signal operation. Here, elements of signal control are discussed, based on the minimization of overall travel times or vehicle queues. Interestingly, we find different operation regimes, some of which involve a “slower-is-faster effect”, where a delayed switching reduces the average travel times. These operation regimes characterize different ways of organizing traffic flows in urban road networks. Besides the optimize-one-phase approach, we discuss the procedure and advantages of optimizing multiple phases as well. To improve the service of vehicle platoons and support the self-organization of “green waves”, it is proposed to consider the price of stopping newly arriving vehicles.
1 Introduction The study of urban traffic flows has attracted the interest of physicists for quite a while (see, e.g., [3, 9, 36, 45]). This includes the issue of traffic light control and the resulting dynamics of vehicle flows [5,7,12,15,37,41,49]. Theoretical investigations in this direction have primarily focussed on single intersections and grid-like street networks, e.g. adaptive control [1, 13, 14] of a single traffic light or coordination of traffic lights in Manhattan-like road networks with unidirectional roads and periodic boundary conditions. Some of the fascination for traffic light control is due to the
First published in: The European Physical Journal B 70(2), 257–274, DOI: 10.1140/epjb/e2009c EDP Sciences, Societa Italiana di Fisica, Springer-Verlag 2009, reproduction 00213-5 (2009), with kind permission of The European Physical Journal (EPJ). D. Helbing () A. Mazloumian ETH Zurich, UNO D11, Universit¨atstr. 41, 8092 Zurich, Switzerland e-mail: [email protected]; [email protected] L. Ambrosio et al., Modelling and Optimisation of Flows on Networks, Lecture Notes in Mathematics 2062, DOI 10.1007/978-3-642-32160-3 7, © Springer-Verlag Berlin Heidelberg 2013
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relationship with the synchronization of oscillators [10, 29, 34] and other concepts of self-organization [16, 17, 24, 25, 28, 33, 38, 44]. The efficiency of traffic light control is essential to avoid or at least delay the collapse of traffic flows in traffic networks, particularly in urban areas. It is also crucial for attempts to reduce the fuel consumption and CO2 emissions of vehicles. Both, delay times and acceleration maneuvers (i.e. the number of stops faced by vehicles)1 cause additional fuel consumption and additional CO2 emissions [32]. Within the USA alone, the cost of congestion per year is estimated to be 63.1 billion US$, related with 3.7 billion hours of delays and 8.7 billion liters of “wasted” fuel [43]. Climate change and political goals to reduce CO2 emissions force us to rethink the design and operation of traffic systems, which contributes about one third to the energy consumption of industrialized countries. On freeways, traffic flows may eventually be improved by automated, locally coordinated driving, based on n
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