Traffic Flow Simulation Model Research Articles

MODELLING HETEROGENEOUS TRAFFIC FLOW ON UPGRADES OF INTERCITY ROADS

The effect of an upgrade and its length is very significant for traffic flow characteristics. Road traffic in developing countries like India is highly heterogeneous comprising vehicles of wide ranging physical dimensions, weight and dynamic characteristics such as engine power, acceleration rate, etc. Due to these variations, the effect of grade on vehicles in heterogeneous traffic may vary significantly among vehicle categories. Variation in the level of the interaction between vehicles on upgrades may result in different sets of traffic flow characteristics. Hence, it is necessary to model traffic flow on upgrades and study, in depth, changes in traffic flow characteristics with alteration in the magnitude of an upgrade and its length. Computer simulation has emerged as an effective technique for modelling traffic flow due to its capability to account for randomness related to traffic. This study is concerned with applying a simulation model of heterogeneous traffic flow, named HETEROSIM, to study the traffic flow characteristics and performance of different vehicle types on upgrades of different magnitudes.

Effect of Gradient and Its Length on Performance of Vehicles under Heterogeneous Traffic Conditions

Study of the basic traffic-flow characteristics and clear understanding of vehicular interaction are the prerequisites for highway capacity and level of service analyses and to formulate effective traffic regulation and control measures. Computer simulation has emerged as an effective technique for modeling traffic flow and to study the flow characteristics over a wide range of roadway and traffic conditions due to its capability to account for the randomness related to traffic. This paper is concerned with application of a simulation model of heterogeneous traffic flow, named HETEROSIM, to quantify the vehicular interaction, in terms of passenger car unit (PCU), for the different categories of vehicles, by considering the traffic flow of representative composition, on up-grades of different magnitudes for intercity roads in India. The PCU estimates, determined through microscopic simulation, for the different types of vehicles in heterogeneous traffic, for a wide range of grades and traffic volumes, indicate that the PCU value of a vehicle significantly changes with change in traffic volume and magnitude of grade and its length.

Study of the impact of exclusive bus lane under highly heterogeneous traffic condition

The objective of this paper is to study and quantify the possible impact of provision of exclusive bus lane under heterogeneous traffic condition. The quantum of increase in level of service of bus due to introduction of exclusive bus lane was determined using a simulation model of heterogeneous traffic flow. The impact of introduction of an exclusive bus lane is measured in terms of reduction in speed of other categories of motor vehicles, due to the consequent reduction in road space, over a wide range of traffic volume. The main finding of the simulation experiment is the quantification of the maximum permissible volume to capacity ratio that will ensure a level of service of C for the traffic stream comprising all the motor vehicles, except the buses, on a typical six-lane and eight-lane divided urban roads. This study is also concerned with estimation of the probable shift of the personal vehicle users to bus due to provision of exclusive bus lanes.

Estimating Modal Shift of Car Travelers to Bus on Introduction of Bus Priority System

Abstract This study is concerned with estimation of the probable shift of car users to bus due to increase in its level of service after providing exclusive bus lanes on Indian city roads carrying heterogeneous traffic. The quantum of increase in level of service of bus due to introduction of exclusive bus lane was determined using a recently developed simulation model of heterogeneous traffic flow. The data of the other factors (variables) that might cause modal shift from car to bus were collected through home-interview survey based on the stated preference approach. A binary Logit model of mode-choice was then calibrated using the collected data and the model was also validated using holdout sample. Through this study, a set of causal factors, with reliable and predictable data base, to explain the variation in shift behaviour of personal vehicle users to buses consequent on the increase in the level of service of buses, has been identified. A mode-choice probability curve to depict the possible modal shift of car users to bus is developed, taking the difference in travel times of the two-modes as the basis, to serve as a user friendly tool to analyze the possible modal shift for a wide range of values of the involved variable.

Simulating Heterogeneous Traffic Flow on Roads with and without Bus Lanes

Exclusive bus lanes are intended to enhance the level of service of bus transport in terms of speed, reliability, safety, etc. This paper is concerned with application of a newly developed microsimulation technique to study the effect of provision of reserved bus lanes on the flow of nonlane-based heterogeneous traffic on urban roads in India. The aim of the study reported here is to modify and validate a newly developed simulation model of heterogeneous traffic flow using field observed data and to apply the validated model to study the effect of exclusive bus lanes on traffic flow. The effect is measured in terms of the reduction in the speeds of other categories of vehicles due to the possible reduction in the available road space for these vehicles. The results of the study indicate that it is possible to introduce exclusive bus lanes on carefully selected urban roads to enhance the level of service of bus, simultaneously ensuring a satisfactory level of service to the other vehicles on the road.

MODELLING MODAL SHIFT DUE TO THE ENHANCED LEVEL OF BUS SERVICE

This study is concerned with the estimation of the probable shift of auto‐rickshaw (three wheeled motorized para‐transit vehicle) users to the bus due to an increase in its level of service after providing exclusive bus lanes on Indian city roads carrying heterogeneous traffic. The quantum of an increase in the level of bus service due to the introduction of an exclusive bus lane was determined using a recently developed simulation model of heterogeneous traffic flow. The data on other factors (variables) that might cause modal shift from the auto‐rickshaw to the bus was collected conducting a home‐interview survey based on the stated preference approach. A binary logit model of mode‐choice was then calibrated using the collected data and the model was also validated using a holdout sample. A mode‐choice probability curve to depict the possible shift of auto‐rickshaw users to the bus is developed taking difference in the travel times of two‐modes as the basis to serve as a user friendly tool to analyze the possible modal shift for a wide range of the values of the involved variables.

Cyclists' path planning behavioral model at unsignalized mixed traffic intersections in China

Study on the cyclist's path planning behavior in mixed traffic flow intersection is very important. The paper presents a fuzzy logic based behavior model to describe cyclist path planning behaviors at unsignalized intersections in mixed traffic flow situations (with many conflicts among motorcars, non-motor vehicles and pedestrians). Field data have been collected for fuzzy logic modeling, model calibration and validation, and the simulation results are promising. The model can be used in mixed traffic flow simulation and path planning models for Personal Mobility Vehicles (PMVs).

The Impact of Cooperative Adaptive Cruise Control on Traffic-Flow Characteristics

Cooperative adaptive cruise control (CACC) is an extension of ACC. In addition to measuring the distance to a predecessor, a vehicle can also exchange information with a predecessor by wireless communication. This enables a vehicle to follow its predecessor at a closer distance under tighter control. This paper focuses on the impact of CACC on traffic-flow characteristics. It uses the traffic-flow simulation model MIXIC that was specially designed to study the impact of intelligent vehicles on traffic flow. The authors study the impacts of CACC for a highway-merging scenario from four to three lanes. The results show an improvement of traffic-flow stability and a slight increase in traffic-flow efficiency compared with the merging scenario without equipped vehicles

TOWARDS A MICROSCOPIC SIMULATION MODEL FOR TRAFFIC MANAGEMENT: A COMPUTER-BASED APPROACH

Traffic congestion is increasing world-wide as a result of increased motorization, urbanization, population growth and changes in population density. Congestion reduces utilization of the transportation infrastructure and increases travel time, air pollution and fuel consumption. Automatic and adaptive control can play a significant corrective role for managing transportation systems in today's highly congested traffic networks. This paper presents the microscopic simulation model development of a major highly congested traffic network of Nicosia, Cyprus. Based on the validated simulation model various traffic control strategies involving the use of intelligent transportation systems will be tested prior to their implementation. Finally, this paper demonstrates a wider spectrum of understanding on the principles of traffic flow theory and how a traffic flow simulation model is developed and utilized for effective transportation planning.

Influence of Bus Stops on Flow Characteristics of Mixed Traffic

The number and type of bus stops provided on a road significantly influence the flow characteristics of traffic on the road. The study of the influence of bus stops on traffic flow under homogeneous traffic conditions has been attempted by several researchers. However, studies on the influence of bus stops on traffic flow under heterogeneous traffic conditions, are found to be absent. This paper is concerned with the study of heterogeneous traffic flow characteristics using a simulation technique with specific reference to the influence of bus stops on the traffic flow. First, an overview of the microscopic traffic-flow simulation model used to study the flow characteristics of nonlane-based heterogeneous traffic on urban road links is given. Then, the validation of the model based on field observed data is described. Finally, the application of the model to study the impact of curbside bus stops and bus bays on the speeds of other vehicles in heterogeneous traffic streams is dealt with. The effects of variation of the basic parameters, such as bus dwell time, road width, and traffic flow level, are examined for both curbside and bus bay type of stops. The usefulness of the model in fixing the traffic flow levels for replacing curbside stops with bus bays, as example, has also been highlighted.

Modelling and Simulation for Safe and Efficient Navigation in Narrow Waterways

This paper outlines the design of a Vessel Traffic Management and Information System (VTMIS) for the Turkish Straits and taking this as an example shows how modelling and simulation may aid safe and efficient navigation of vessels through waterways which are narrow and winding with changing currents and are therefore difficult to navigate and prone to accidents. Ship Handling and Vessel Traffic Flow simulation models and Hyrographic Prediction model are described and the simulation trials conducted under different traffic and environment conditions are discussed to show the role that these prediction and simulation programmes can play in preventing marine casualities in different waterways, which may result in loss of human lifes and property and contamination of the environment.

Park and Ride Strategy Evaluation System Combining Modal Choice Models with the Microscopic Traffic Simulation

For the planning of the park-and-ride (P&R) strategy in urban areas, it is necessary to estimate the P&R demand appropriately corresponding to the conditions of the policy measure, i. e. size, location and charge of the P&R facilities. In addition, traffic flow conditions caused by the change in demand must be also evaluated. In this study, a modal choice model which includes the access mode choice behavior is developed and change in the demand is expressed by that. A microscopic traffic flow simulation model is also developed in order to express the spatial distribution of the traffic flow conditions dynamically. By combining these models and adding the dynamic park-and-ride (DP&R) choice model to that, a P&R strategy evaluation system is structured, which enables to simulate the entire intermodal trip from origin to destination and the traffic flow in the network. Furthermore, applying this system to the eastern part of Nagoya City, effects by the P&R related measures such as settlement of parking facilities and DP&R are discussed.

Microscopic Model of Air Pollutant Concentrations: Comparison of Simulated Results with Measured and Macroscopic Estimates

Road traffic is a major source of air pollution, and substantial effort is currently being devoted to the development of both technological and transport policy measures to reduce the impacts. It is well established that the emission of certain pollutants is closely related to both traffic speed and fluctuations in traffic speed. However, conventional transport emission models are largely based on average traffic conditions, and thus they cannot properly represent the effects of policy measures, such as automatic speed control or traffic calming, that directly affect the speed dynamics of the traffic stream. Given the prevalence of such policies, there has been considerable effort to develop improved emissions modeling capabilities. A new approach to the microscopic modeling of air pollution from road traffic is described. This approach can represent detailed speed fluctuations in the flow of traffic, and it is applied to a local network in Maidstone, Kent, in the United Kingdom. A stochastic microscopic traffic flow simulation model (VISSIM), an existing speed-based emission database (MODEM), and a Gaussian dispersion model are combined. Simulated results are compared with a macroscopic model of air pollutant concentrations (DMRB method) and roadside pollutant measurements. Results are encouraging and show a good comparison with the DMRB method and, with some exceptions, good comparisons with trends in measured pollutant concentrations. Statistical differences in the methods, however, suggest that either measurement error or other inaccuracies are present.

Dynamic Estimation of Origin-Destination Travel Time and Flow on a Long Freeway Corridor: Neural Kalman Filter

A model was formulated for estimating dynamic origin-destination (O-D) travel time and flow on a long freeway with a neural Kalman filter originally developed by the authors. The model predicts O-D travel times and flows simultaneously by using traffic detector data such as link traffic volumes, spot speeds, and off-ramp volumes. The model is based on a Kalman filter that consists of two equations: state and measurement. First, the state and measurement equations of the Kalman filter were modified to consider the influence of traffic states for some previous time steps. Then artificial neural network models were integrated with the Kalman filter to enable nonlinear formulations of the state and measurement equations. Finally, a macroscopic traffic flow simulation model was introduced to simulate traffic states on a freeway in advance and predict traffic variables such as O-D travel times, link traffic volumes, spot speeds, and off-ramp volumes. The new model was compared with a regression Kalman filter in which the state and measurement equations are defined by regression models. The numerical analysis indicated that the new model was capable of estimating nonlinearity of dynamic O-D travel time and flow and helped to improve their estimation precision under free-flow traffic states as well as congested flow states.

Parametrization of Microscopic Traffic Flow Models Through Image Processing

Abstract Some decisions of urban traffic control are based on microscopic traffic flow simulation models. In each application parameters describing locally observed driving behaviour as well as parameters setting up the network have to be adjusted. To reduce the effort needed for calibration and validation this study deals with a parametrization method through image processing. Within the study one image processing system is applied to calibrate parameters of the microscopic traffic flow model of WIEDEMANN. A Simulated Annealing Algorithm is used to match observed and simulated values. Results of the calibration process are outlined using a partially signalized roundabout

Feasibility Study of Park and Bus-Ride System for Counterplan of Traffic Jam caused by Skiers

In this paper, we deal with the traffic jam caused by visiting skiers, and we investigated the feasibility study of Park and Bus-Ride system. The P&BR system was evaluated by combination model which are conjoint analysis and traffic-flow simulation model. Yuzawa town in niigata prefecture took up the object of this case study.

Control Strategies for Increasing Motorway Capacity

This paper presents an analysis of parametric control strategies on motorways based on speed control obtained by imposing speed limits. The influence of these strategies on drivers’behaviour is examined by a simulation model of traffic flow on motorways; the effect on reliability of the transport system is analysed studying the structure of speed processes on a cross section of carriageway. It is verified that these strategies are very effective in increasing reliability and capacity of motorways travelled by high traffic volumes of habitual drivers - e.g. commuters during peak hours - but their contribution is of little importance if drivers are occasional motorway users.

Road traffic simulation model for predicting pollutant emissions

A digital computer simulation model of traffic flow and pollution emissions has been developed for free-flow situations using car-following theory and constrained random input to predict the emissions of gaseous pollutants in the atmosphere emitted from different types of vehicles on the road. The type of vehicle, its position, speed and acceleration are then used to predict the total pollutant emissions in the atmosphere. The model is designed to find the pollutants emission of nitrogen oxides as NO 2 and hydrocarbons as CH 3 emitted to the atmosphere from different types of vehicles by free-flowing traffic on the road. The program summed up the pollutant emissions for all vehicles in the system to represent the total emissions of pollutants. The model is then used to examine various traffic and pollutant control strategies.