Cellular Automata Based Traffic Flow Model Considering Limited Deceleration Capability

To identify and investigate the characteristics of traffic flow, many theoretical model had been developed. They are macroscopic continuum models, car following models and cellular automata models. Cellular automata models are now widely applied in traffic studies because they are discretized in both time and space and can be easily realized by computers.The realistic traffic components are not homogeneous but a mixture of different types of vehicles. The basic properties of vehicles are changing from type to type in terms of length, acceleration and deceleration abilities. Although many cellular automata models are developed to study the mixing traffic but most of them ignore the constraints of vehicle deceleration ability. Understanding this fact, a cellular automata model considering the deceleration ability of vehicles is developed and simulated in order to identify the basic characteristics of mixing traffic flow on two lanes carriageway.The main works of this studies are:1. Investigate the cellular automata traffic model considering space gap, relative velocity of adjacent vehicle and limited deceleration capability. The simulation results show that if there is no slow-start principle or the slow-start critical speed is very low in the model, flow rate and average speed decrease as the deceleration capability decrease. Then the impact of rain are modeled by setting different maximum speed and deceleration capability for different rain conditions. The simulation result illustrates that within a certain range of density, traffic flow and average speed increase as the rainfall intensity decreases. And the different rain conditions had no significant impact on traffic flow when traffic density increases.2. Introduce the lane-changing and heavy truck active deceleration rules, extend the single-lane homogenous traffic model to two-lane mixing traffic model. The two-lane mixing traffic model not only considered space gap, relative velocity of adjacent vehicle and limited deceleration capacity but also basic properties like vehicle length, maximum acceleration and deceleration capacity. The analysis result shows the model can realize all the three phases of traffic flows namely:free flow, synchronized flow and wide moving jam, when the traffic flow density is between certain rage, the synchronized flow occurs randomly. The heavy truck active deceleration rule introduced in this project can eliminate the negative effect when two heavy trucks running in parallel, through controlling of active deceleration rule, the traffic throughput can increase significantly.3. Utilizing VT-Micro vehicle fuel consumption and emission model to calculate the energy usage and emission of both single-lane homogenous traffic flow and two-lane mixed traffic flow in terms of CO2 and NOx, the simulation results indicate that fuel consumption and CO2 is in direct proportion to traffic low density, NOx emission increase at first, then decrease and increase again, fuel consumption and emission is in inverse proportion to vehicle deceleration capacity. In additional, the more proportion of heavy trucks in the traffic, the more energy consumption and CO2 emission can be detected.