The Experts below are selected from a list of 405309 Experts worldwide ranked by ideXlab platform
Roberto Horowitz - One of the best experts on this subject based on the ideXlab platform.
-
Simulation of Arterial Traffic Using Cell Transmission Model
2013Co-Authors: Alex A. Kurzhanskiy, Roberto HorowitzAbstract:Cell Transmission Model (CTM) is one of the widely used macroscopic traffic Models. There was a lot of research to show this Model could provide reliable simulation of freeway traffic and it has many applications in traffic management design. But there was insufficient proof to demonstrate this Model can accurately simulate urban traffic. This paper illustrates the use of cell Transmission Model on a segment of signalized arterial. The data source is the NGSIM data collected on Lankershim Blvd. The simulation result agrees with the measurement.
-
optimal freeway ramp metering using the asymmetric cell Transmission Model
Transportation Research Part C-emerging Technologies, 2006Co-Authors: Gabriel Gomes, Roberto HorowitzAbstract:The onramp metering control problem is posed using a cell Transmission-like Model called the asymmetric cell Transmission Model (ACTM). The problem formulation captures both freeflow and congested conditions, and includes upper bounds on the metering rates and on the onramp queue lengths. It is shown that a near-global solution to the resulting nonlinear optimization problem can be found by solving a single linear program, whenever certain conditions are met. The most restrictive of these conditions requires the congestion on the mainline not to back up onto the onramps whenever optimal metering is used. The technique is tested numerically using data from a severely congested stretch of freeway in southern California. Simulation results predict a 17.3% reduction in delay when queue constraints are enforced.
-
Methodological calibration of the cell Transmission Model
Proceedings of the 2004 American Control Conference, 2004Co-Authors: L. Munoz, Dengfeng Sun, Xiaotian Sun, Gabriel Gomes, Roberto HorowitzAbstract:A semi-automated method has been developed for calibrating the parameters of a modified version of Daganzo's cell Transmission Model (CTM). A least-squares data fitting approach was applied to loop detector data to determine free-flow speeds, congestion-wave speeds, and jam densities for specified subsections of a freeway segment. Bottleneck capacities were estimated from measured mainline and on-ramp flows. The calibration method was tested on a 14-mile portion of Interstate 210 Westbound in southern California. The calibrated CTM was able to reproduce observed bottleneck locations and the approximate behavior of traffic congestion, yielding approximately 6%, or less, error in the predicted total travel time.
-
traffic density estimation with the cell Transmission Model
American Control Conference, 2003Co-Authors: L. Munoz, Roberto Horowitz, Luis Javier AlvarezAbstract:A macroscopic traffic flow Model, called the switching-mode Model (SMM), has been derived from the cell Transmission Model (CTM) and then applied to the estimation of traffic densities at unmonitored locations along a highway. The SMM is a hybrid system that switches among different sets if linear difference equations, or modes, depending on the mainline boundary data and the congestion status of the cells in a highway section. Using standard linear systems techniques, the observability and controllability properties of the SMM modes have been determined. Both the SMM and a density-based version of the CTM have been simulated over a section of I-210 West in Southern California, using several days of loop detector data collected during the morning rush-hour period. The simulation results show that the SMM and CTM produce density estimates that are both similar to one another and in good agreement with measured densities on I-210. The mean percentage error averaged over all the test days was approximately 13% for both Models.
Antonella Ferrara - One of the best experts on this subject based on the ideXlab platform.
-
A Variable-Length Cell Transmission Model for Road Traffic Systems
Transportation research. Part C Emerging technologies, 2018Co-Authors: Carlos Canudas De Wit, Antonella FerraraAbstract:In this paper we propose a new aggregated Variable-Length cell Transmission Model (VLM) for traffic systems consisting of only three lumped state variables. The first two state variables are the lumped (or averaged) densities associated with the two cells of variable length into which the considered road section is subdivided. These cells are, respectively, a downstream congested cell, of length l, and an upstream free cell, of length L − l, L being the total length of the section. The third state, namely l, describes the position of the congestion wave front. The paper, apart from providing the new traffic Model formulation, also investigates several mathematical properties of this Model, ensuring the consistency with respect to its inherent mass (or vehicle) conservation law. Two case studies, a ring road and a urban road with traffic lights, are considered to assess the proposed Model validity also relying on simulation evidence.
Carlos Canudas De Wit - One of the best experts on this subject based on the ideXlab platform.
-
A Variable-Length Cell Transmission Model for Road Traffic Systems
Transportation research. Part C Emerging technologies, 2018Co-Authors: Carlos Canudas De Wit, Antonella FerraraAbstract:In this paper we propose a new aggregated Variable-Length cell Transmission Model (VLM) for traffic systems consisting of only three lumped state variables. The first two state variables are the lumped (or averaged) densities associated with the two cells of variable length into which the considered road section is subdivided. These cells are, respectively, a downstream congested cell, of length l, and an upstream free cell, of length L − l, L being the total length of the section. The third state, namely l, describes the position of the congestion wave front. The paper, apart from providing the new traffic Model formulation, also investigates several mathematical properties of this Model, ensuring the consistency with respect to its inherent mass (or vehicle) conservation law. Two case studies, a ring road and a urban road with traffic lights, are considered to assess the proposed Model validity also relying on simulation evidence.
-
An Average Study of the Signalized Cell Transmission Model
2017Co-Authors: Carlos Canudas De WitAbstract:—In this paper we present an average study between the continuous-time signalized T-periodic Link Transmission Model (LTM), and its averaged version. Those are macroscopic Models capturing the time-evolution of the vehicles densities in urban traffic networks controlled by periodic traffic light of period T. In this paper, we formalize the mathematic sense in which the solutions of the periodic signalized LTM Model are approximated by the solutions of its averaged version. In particular, we shown that the error norm between the solutions of the signalized and the averaged Models is bounded, in both a finite and infinite time-intervals, by constant proportional to the the ratio, T /L, between the traffic light time-cycle T , and the considered road segment (link) length, L. This result confirm the intuition that the precision of the averaged Models improves with the increase of traffic light frequencies and link road lengths.
-
An efficient one-step-ahead optimal control for urban signalized traffic networks based on an averaged Cell-Transmission Model
2015Co-Authors: Pietro Grandinetti, Carlos Canudas De Wit, Federica GarinAbstract:— This paper presents a Model for large urban traffic networks, based on the well-known macroscopic Cell Transmission Model. We start by describing the dynamics of traffic flow at signalized intersections. Then we develop an average-based approximation of such a system, that we use to build our control algorithm as a linear optimization problem. Simulation results validate the averaged approach and show the effectiveness of the proposed control strategy.
W Y Szeto - One of the best experts on this subject based on the ideXlab platform.
-
stochastic cell Transmission Model sctm a stochastic dynamic traffic Model for traffic state surveillance and assignment
Transportation Research Part B-methodological, 2011Co-Authors: Agachai Sumalee, R X Zhong, W Y SzetoAbstract:The paper proposes a first-order macroscopic stochastic dynamic traffic Model, namely the stochastic cell Transmission Model (SCTM), to Model traffic flow density on freeway segments with stochastic demand and supply. The SCTM consists of five operational modes corresponding to different congestion levels of the freeway segment. Each mode is formulated as a discrete time bilinear stochastic system. A set of probabilistic conditions is proposed to characterize the probability of occurrence of each mode. The overall effect of the five modes is estimated by the joint traffic density which is derived from the theory of finite mixture distribution. The SCTM captures not only the mean and standard deviation (SD) of density of the traffic flow, but also the propagation of SD over time and space. The SCTM is tested with a hypothetical freeway corridor simulation and an empirical study. The simulation results are compared against the means and SDs of traffic densities obtained from the Monte Carlo Simulation (MCS) of the modified cell Transmission Model (MCTM). An approximately two-miles freeway segment of Interstate 210 West (I-210W) in Los Ageles, Southern California, is chosen for the empirical study. Traffic data is obtained from the Performance Measurement System (PeMS). The stochastic parameters of the SCTM are calibrated against the flow-density empirical data of I-210W. Both the SCTM and the MCS of the MCTM are tested. A discussion of the computational efficiency and the accuracy issues of the two methods is provided based on the empirical results. Both the numerical simulation results and the empirical results confirm that the SCTM is capable of accurately estimating the means and SDs of the freeway densities as compared to the MCS.
Satish V Ukkusuri - One of the best experts on this subject based on the ideXlab platform.
-
unified framework for dynamic traffic assignment and signal control with cell Transmission Model
Transportation Research Record, 2012Co-Authors: H Abdul M Aziz, Satish V UkkusuriAbstract:This research presents a unified framework for dynamic traffic assignment and signal control optimization. An objective function based on the system-optimal approach with an embedded traffic flow Model (the cell Transmission Model) for dynamic traffic assignment was considered. The optimization Model (a mixed-integer program) explicitly considered intersection delay and lost time from phase switches in addition to a traditional travel time objective. Two test networks were used to demonstrate the applicability of the proposed Model. Results showed better performance of the Models when they were compared with fixed-signal timing plans. The formulation of signal control design also accounted for the variation of cycle length, and results showed the variation of cycle lengths with different objective functions under different levels of congestion.
