28,506 research outputs found
Calibration of traffic flow models
This study proposes a methodology to calibrate microscopic traffic flow simulation models. A Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm searches for the set of model parameters that minimizes the difference between actual and simulated value
Particle filter state estimator for large urban networks
This paper applies a particle filter (PF) state estimator to urban traffic networks. The traffic network consists of signalized intersections, the roads that link these intersections, and sensors that detect the passage time of vehicles. The traffic state X(t) specifies at each time time t the state of the traffic lights, the queue sizes at the intersections, and the location and size of all the platoons of vehicles inside the system. The basic entity of our model is a platoon of vehicles that travel close together at approximately the same speed. This leads to a discrete event simulation model that is much faster than microscopic models representing individual vehicles. Hence it is possible to execute many random simulation runs in parallel. A particle filter (PF) assigns weights to each of these simulation runs, according to how well they explain the observed sensor signals. The PF thus generates estimates at each time t of the location of the platoons, and more importantly the queue size at each intersection. These estimates can be used for controlling the optimal switching times of the traffic light
Noise emission corrections at intersections based on microscopic traffic simulation
One of the goals of the European IMAGINE project, is to formulate strategies to improve traffic modelling for application in noise mapping. It is well known that the specific deceleration and acceleration dynamics of traffic at junctions can influence local noise emission. However, macroscopic traffic models do not always model intersections, and if they do, only the influence of intersections on travel time is incorporated. In these cases, it would be useful to know what increase or decrease in noise production can be expected at or near intersections. A correction factor for road crossings has been suggested in several national noise emission standards. The question is open whether such a correction factor should be included in future harmonized methods. In this paper, a case study is presented, consisting of a large set of microscopic traffic simulations and associated noise emission calculations, which provides some insight into the specific dynamics of the noise emission near different types of intersections. A spatial approach is used, in which inbound and outbound lanes are divided into deceleration, queuing and acceleration zones. Results from regression analysis on the numerical simulations indicate that meaningful relations between noise corrections and traffic flow parameters such as traffic intensity and composition can be deduced
Anomaly Detection using Microscopic Traffic Variables on Freeway Segments
This paper proposes and assesses the effectiveness of monitoring vehicular traffic anomalies using microscopic traffic variables, namely relative speed and inter-vehicle spacing. We present an algorithm that detects transient changes in traffic patterns using microscopic traffic variables. In particular, we show that when applied to real-world scenarios, our algorithm can use the variance of statistics of relative speed to detect traffic anomalies and precursors to non-recurring traffic congestion. The performance of the proposed algorithm is also assessed using a microscopic traffic simulation environment, where we show that with minimum prior knowledge, the proposed algorithm has comparable performance to an ideally placed loop detector monitoring the standard deviation of speed. The algorithm also performs very well even when the microscopic traffic variables are available only from a fraction of the complete population of vehicles.Accepted versio
Change in Microscopic Traffic Simulation Practice with Respect to the Emerging Automated Driving Technology
It is believed that autonomous vehicles will replace conventional human drive vehicles in the next decades due to the emerging autonomous driving technology, which will definitely bring a massive transformation in the road transport sector. Due to the high complexity of traffic systems, efficient traffic simulation models for the assessment of this disruptive change are critical. The objective of this paper is to justify that the common practice of microscopic traffic simulation needs thorough revision and modification when it is applied with the presence of autonomous vehicles in order to get realistic results. Two high-fidelity traffic simulators (SUMO and VISSIM) were applied to show the sensitivity of microscopic simulation to automated vehicle’s behavior. Two traffic evaluation indicators (average travel time and average speed) were selected to quantitatively evaluate the macro-traffic performance of changes in driving behavior parameters (gap acceptance) caused by emerging autonomous driving technologies under different traffic demand conditions
A Continuous Topography Approach for Agent Based Traffic Simulation, Lane Changing Model
Traffic simulation has been being an interesting research subject for transport engineer and scientist, mathematicians and informatics scientist for different point of view. Transport scientists study the traffic complexity and behaviour of traffic participants by using statistical experiment or simulation. The earlier approach was based on macroscopic model deducted from hydrodynamics kinematic wave analogy. Later on the microscopic model was introduced first by invoking cellular automata and then agent based model takes important role in the traffic simulation world. Most of microscopic model are based on a multi-grid element topography model which is a natural environment of cellular automata. Just recently a software engineer started an ambitious work to develop a multipurpose framework for complex traffic simulation. The ingenious idea is to replace the traditional grid based element topography with a continuous two dimensional one from which a region of traffic road or street is built up. Traffic participant is modelled as agent whose physical properties such as its coordinate position, speed, and direction are governed by the kinematic Newtonian law. This article will present this new concept and show how the simple movement of lane changing model that is very well known from the beginning era of traffic simulation become a quite complex movement in the new continuous topograph
Modelling and Control of Freeway Traffic
This paper presents the most recent developments of the Simulator
of Intelligent Transportation Systems (SITS). The SITS is based on a microscopic
simulation approach to reproduce real traffic conditions in an urban or non-urban
network. In order to analyse the quality of the microscopic traffic simulator SITS
a benchmark test was performed. A dynamical analysis of several traffic phenomena,
applying a new modelling formalism based on the embedding of statistics and
Laplace transform, is then addressed. The paper presents also a new traffic control
concept applied to a freeway traffic system
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