1,720,960 research outputs found
A new node model based on CTM-UT with capacity determination
No full textDespite the results obtained in literature to improve the macroscopic node model it is necessary to consider a general node model approach. A general node approach could take into account different aspects about conflicts at intersections. In this paper, we present a new node model based on CTM to represent traffic flows that crosses signalized and unsignalized intersections. It allows to model complex intersections for urban contest. In particular, to represent different turn movements of the inflow at intersection and belonging at the same lane, the model introduces a new variable. It is utilized to represent the percentages of different turns. The model takes into account also the estimation of the merge flows at the intersection. We present a new model to compute the minor streams that are limited by major stream on unsignalized intersections. This model reduces the problems and the complexities of the capacity determination (based on gap acceptance) and it could be used for dynamic traffic assignment. Our model could be used also for complex signalized intersection, where many conflicts among through flows are presented
A distributed approach for traffic signal synchronization problem
No full textIn this work a distributed algorithm for the optimization of signal setting on urban network is proposed. The Traffic Signal Synchronization is a traffic engineering technique of matching the green light times for a series of intersections to enable the maximum number of vehicles to pass through, thereby reducing stops and delays experienced by motorists. Synchronizing Traffic Signals ensures a better flow of traffic and minimizes gas consumption and pollutant emissions. In this paper we provide a solution to the traffic signals problem via simulation.The objective function used in this work is a weighted sum of the delays caused by the signalized intersections, and it is calculated by CTM UT model via simulation. We proposed a decomposition of the network, considering the cooperation between different subnetworks. Given the subnetworks the surrogate method is applied to solve the Traffic Signal Synchronization problem. Numerical experiments on test network are reported
Performance Analysis of Decentralized VS Centralized Control for the Traffic Signal Synchronization Problem
Full text linkThis paper suggests the adoption of a spatial decomposition method to solve the signal synchronization problem. A good signal setting maximizes the number of vehicles passing through intersections, while minimizing gas emissions and possible delays experienced by drivers. The signals synchronization issue can be defined as the problem of finding the offsets, the green timings, and the cycle length for a series of controlled intersections, minimizing the total delay of the network subject to admissibility constraints. In this paper, the authors optimized the signal setting through a new Surrogate Method calculating the objective function via the CTMUT model while performing a simulation. A spatial decomposition approach is here suggested with a simultaneous analysis of different levels of cooperation among subnetworks. This study tries to identify a subnetwork that might be representative of the entire network while taking into consideration two factors: efficiency and efficacy. A comparison between centralized and decentralized control is performed
An urban traffic flow model to capture complex flow interactions among lane groups for signalized intersections
No full textThis paper presents a traffic flow model, based on cell transmission concept, to capture urban traffic dynamics taking into account complex flow interactions among lane groups at upstream of signalized intersections. This model is a simple and versatile simulation framework designed to simulate, at macroscopic level, more realistically the dynamic interaction of queues among neighboring lanes and intersections for large scale urban network. Model validation has been undertaken by comparing with Vissim results obtained in different scenarios that have been tested
A new methodology to calibrate the congestion wave for the Cell Transmission Model for urban traffic
No full textThis paper presents a new traffic flow model to capture complex urban traffic dynamics. We present an extension of the Cell Transmission Model for Urban Traffic (CTM-UT). It is suitable to represent complex flow interactions among lane groups at upstream of signalized intersections and at intersection with determination capacity. Our model is a simple and versatile simulation framework designed to realistically simulate the dynamic queue interactions. It can represent the potential capacity of minor flow obstructed at intersection for large scale urban network. In this paper we present our macroscopic simulation model considering also an optimization calibration method for congestion wave. A comparison between our model and Simulation of Urban MObility (SUMO) is done
Distributed urban traffic signal optimization based on macroscopic model.
No full textIn this work an analysis of a distributed algorithm for the optimization of signal setting on urban network is proposed. The Traffic Signal Synchronization is a traffic engineering technique of matching the green light times for a series of intersections to enable the maximum number of vehicles to pass through, thereby reducing stops and delays experienced by motorists. Synchronizing Traffic Signals ensures a better flow of traffic and minimizes gas consumption and pollutant emissions. In this paper we compare a decentralized optimization approach with a global one. The analyse is done via simulation. The objective function used in this work is a weighted sum of the delays caused by the signalized intersections, and it is calculated via simulation by CTM-UT model. We used a classification method to reduce the network, and also a cooperation between signal setting is considered. The synchronisation of the signal setting is done by the surrogate approach, and an analysis on this approach is done. Numerical experiments on test network are reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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