Modeling and simulation of highway traffic using a cellular automaton approach

The purpose of this paper is to discover how Cellular Automata (CA) can be applied to traffic flow simulations. First, we introduce the three types of traffic model: microscopic traffic model, macroscopic traffic model and mesoscopic traffic model. Second, to evaluate dynamic traffic flow, we developed a traffic flow simulator that uses cellular automata model. We extend the existing CA models to describe the influence of a car accident in single-lane and double-lane traffic flow model. We also add the lane changing rules to simulate the reality traffic condition. By simulation, we analyze all possible situations. The simulation was implemented in Matlab programming language. 1. Main Features of Traffic Stream Traffic phenomena are an important question in modern society. Investigating on regular pattern of traffic flow has significant meaning. Analysis and simulation of traffic flow can be wildly applied in Transportation Planning, Traffic Control and Traffic Engineering. In the early 90S, New York City government decided to construct the tunnel to New Jersey. After analyzed and modeled the traffic flow, they adjusted traffic management strategy which increased the capacity of current existing facilities. So the tunnel construction was avoided. Traffic stream is complex and nonlinear and defined as multi-dimensional traffic lanes with flow of vehicles over time. Traffic phenomena are complex and nonlinear. Vehicles followed each other on each lane and they can choose different lane when the former position is empty. There are three main characteristics to visualize a traffic stream: speed, density, and flow. 1.1. Speed, Density and Flow Speed (V) is defined as travel distance per unit time in traffic flow. The precise speed of each car is difficult to measure. In practice, we calculate the average speed of the sample vehicles. In a time space diagram, time is measured along the horizontal axis and distance is measured along the vertical axis. The velocity of the traffic stream equals to the slope of the traffic trajectory (v=dx/dt).The figure below shows the nonlinear traffic stream. The common method speed is to calculate the time mean speed. Time mean speed is measured by the average speed of a traffic stream passing a fixed point along a roadway over a fixed period of time. Time mean speed can be sampled by loop detectors and other fixed-location speed detection equipment. The time-mean speed can be calculated as: