Traffic-light Cycle Coordinated by Microsimulation: a Solution to the Traffic Congestion in Palermo Giuseppe Salvo and Luigi Sanfilippo Technology and Economy of Transport University of Palermo Palermo {giuseppe.salvo, luigi.sanfilippo}@unipa.it Abstract—This article aims to highlight the results of an analysis of the traffic management carried out by the Department of Civil Engineering of the University of Palermo, through traffic microsimulation model and mathematical calculations. In this paper, we demonstrate the usefulness of a coordinated traffic light cycle in an area of Palermo with high traffic flow. To achieve this, we used microsimulation for planning traffic lights, we calculated mathematically the phases in traffic lights and we made changes in the geometry of the intersection. Although this approach is not new, we would like to emphasize the importance of the use of microsimulation models in urban planning of medium-size cities, such as Palermo, characterized by a high rate of traffic congestion. Keywords- microsimulation model; traffic lights. I. INTRODUCTION Mobility is one of the most important elements of a modern society [1] and traffic congestion has been causing many critical problems [2]. Palermo, as many cities and towns in the world, is subject to high traffic flows and their corresponding consequences in terms of air pollution, congestion, and decreased levels of safety. A proper planning of traffic-light cycle could reduce this kind of problems, improving vehicles flow. Some of the advantages of intersection traffic lights include: homogeneous traffic flows, orderly movement of vehicular currents, reduction of the frequency of accidents [3][4][5][6]. The traffic lights planning cycle is a task often complicated by the number of traffic lights installed in the urban road network: when the nearby traffic lights operate independently, vehicles have a bumpy ride because of the ongoing stops and starts, resulting in degraded performance and increased pollution. To synchronize and coordinate systems means to link them together so as to achieve a constant rate in turning green [7]. It is therefore essential to have a proper synchronization of intersections, whose programming is most often preceded by simulations carried out by the use of microsimulation models. These are a source of immediate and continuous information on the traffic flow [8][9][10][11]. Thanks to the development of innovative software, models capable of representing the dynamic of flow conditions, which actually occurs on road infrastructure, have been created. Depending on the level of aggregation, there are three main types of models: macroscopic models, mesoscopic models, and microscopic models. In macroscopic models, traffic flow is defined by the rules of conduct that are a function of the interaction of vehicles with each other and with the infrastructure, and the main variables that are taken into consideration are flows, velocity and density [13]. In this type of model, the current traffic as a whole is analyzed, and not the individual vehicles in the network; therefore, these models are called "continuous". Mesoscopic models differ from macroscopic models by the fact that they consider the current traffic by dividing it into groups of vehicles, which can be, for example, the platoons that move in response to a traffic light stop. Microscopic models, or microsimulation models, differ from the two first mentioned as the smallest unit analyzed is represented by the single vehicle, which moves on the road network and interacts with the other vehicles and with the infrastructure, according to a series of parameters that depend on instantaneous velocity, acceleration, drivers behavior, and mutual distances between the vehicles themselves [13]; these models are then "discrete". In this paper, we present a microsimulation application related to the area between piazza Don Bosco and piazza Leoni in Palermo (Figure 11), classified in the urban traffic plan as interdistrict roads because of the connection between the city center with Mondello. Using microsimulation models, two scenarios are analyzed: • The current scenario (with uncoordinated traffic lights cycles); • The project scenario (with coordinated traffic light cycles). In the following section, we describe the current scenario by providing an overview of the intersection arrangement. We also describe the scheme used for the construction of the microsimulation model: matrix origin/destination and the other variables useful for the analysis (e.g., travel times, traffic signal cycle times, etc.). In the third section, the project scenario is described. In this scenario, differently from the present scenario, the traffic light synchronization is implemented, and we hypothesize a change at the intersection of piazza Leoni. In addition, we provide useful calculations for analysis scenario and in comparison to the present scenario (e.g., saturation flux, load index, equivalent courses, cycle traffic lights, etc.). SIMUL 2014 : The Sixth International Conference on Advances in System Simulation Copyright (c) IARIA, 2014. ISBN: 978-1-61208-371-1 7