Showing papers on "Traffic simulation published in 1993"

Simulation Of Freeway Incident Detection Using Artificial Neural Networks

Abstract: A major source of traffic delay in many large urban areas in the United States is non-recurring congestion caused by incidents. In the last several decades, a number of incident detection algorithms have been developed for freeway surveillance and control systems. However, conventional algorithms have generally met with mixed success in terms of performance criteria, such as detection rate, false alarm rate, and the mean time to detect incidents. The need for improved techniques is pressing, particularly with the advent of intelligent vehicle-highway system concepts. These systems will rely heavily on the ability to detect non-recurring traffic congestion automatically. In this paper, we hypothesize that spatial and temporal traffic patterns can be recognized and classified by an artificial neural network, and we present an investigation of such models for the automated detection of lane blocking incidents in a one-mile section of urban freeway. The artificial neural network was trained with data obtained from a microscopic freeway traffic simulation model that was specially calibrated for the actual freeway test section. The neural network first classifies the traffic state of the freeway section into either “incident-free” or “incident” conditions in every 30-second interval. The change in traffic state from incident-free to incident conditions is then used to trigger an incident alarm. Based on the results of an off-line test using simulated data, and comparisons with the well known California incident detection algorithm and the recently developed modified McMaster algorithm, the results suggest that neural network models have the potential to achieve significant improvements in incident-detection performance.

In-laboratory experiments to investigate driver behavior under advanced traveler information systems (atis). working paper

Abstract: In laboratory experimentation with interactive microcomputer simulation is a useful tool for studying the dynamics of driver behavior in response to advanced traveler information systems. Limited real-world implementation of these information systems has made it difficult to observe and study how drivers seek, acquire, process, and respond to real-time information. This paper describes the design and preliminary testing of an interactive microcomputer-based animated simulator, developed at the University of California, Irvine, to model pre-trip and enroute driver travel choices in the presence of advanced traveler information systems. The advantages of this simulator are realized in its versatility to model driver decision processing while presenting a realistic representation of the travel choice domain. Results from a case study revealed that increased driver familiarity with travel conditions and network layout reduces driver reliance on information systems and influences drivers diversion behavior.

Simulating the evacuation of a small city: the effects of traffic factors

Abstract: A behavioral-based simulation model for spontaneous urban evacuation is used to examine the sensitivity of network clearance time to several traffic factors (e.g. interaction with pedestrians, intersection traversing time, and car ownership) and route choice mechanisms (shortest path and myopic behavior). It is a micro traffic simulation model based on stochastic simulation of series of events in a radiological emergency situation. Evacuation time comes closer to reality when interaction with pedestrians and a uniform distribution of intersection traversing time are assumed. More realistic results are also found whenever routes are selected according to the maximal distance from the last car. The sensitivity of clearance time to population growth and car ownership indicates that the model can be easily applied to cities of various sizes.

Elevator Traffic Simulation

Abstract: Passenger waiting time in a lobby and ride time in a car give a good indication of the service capability of an elevator group. If several cars are in the same group, these parameters are too complicated to model in a closed form. In this paper, procedures for modelling elevator performance and passenger traffic in a generic building are described. Elevator dynamics and control, call allocation and passenger traffic modelling are described. Simulated interval and load values are compared with theoretical results, and variances in simulation results are investigated. According to typical simulation results, there is no direct connection between interval and passenger waiting times, as is often assumed. The interval depends on the elevator bank configuration and elevator performance capabilities. Performance indicators, such as the number of starts and cycle times, become saturated even at low traffic intensities. The waiting times, in addition to elevator performance, depend on the passenger traffic patter...

Vehicle probes as real-time atms sources of dynamic o-d and travel time data

Abstract: This paper has two main objectives. First, the process of obtaining network traffic data from probe vehicles is examined such that statistical sampling equations can be developed that provide both theoretical and practical estimates of the reliability of these probe data. Second, using an example network, the traffic simulation model results are compared against the analytical results. The validation of simulation based results permits the simulation model to be used for more complex situations, for which statistical analyses are no longer practical, and to determine the overall impact of the various statistical approximations that had to be made within the analytical solutions.

An investigation of the reliability of real-time information for route choice decisions in a congested traffic system

Abstract: This paper investigates the reliability of information on prevailing trip times on the links of a network as a basis for route choice decisions by individual drivers. It considers a type of information strategy in which no attempt is made by some central controller or coordinating entity to predict what the travel times on each link would be by the time it is reached by a driver that is presently at a given location. A specially modified model combining traffic simulation and path assignment capabilities is used to analyze the reliability of the real-time information supplied to the drivers. This is accomplished by comparing the supplied travel times (at the link and path levels) to the actual trip times experienced in the network after the information has been given. In addition, the quality of the decisions made by drivers on the basis of this information (under alternative path switching rules) is evaluated ex-post by comparing the actually experienced travel time (given the decision made) to the time that the driver would have experienced without the real-time information. Results of a series of simulation experiments under recurrent congestion conditions are discussed, illustrating the interactions between information reliability and user response.

Exploring real-time traffic simulation with massively parallel computing architecture

Abstract: The advent of parallel computing architectures presents an attainable opportunity for transportation professionals to simulate a large-scale traffic network with sufficiently fast response time for real-time operation. However, it necessitates a fundamental change in the modelling algorithm to take full advantage of parallel computing. Currently there are two general types of parallel processing architectures: (a) single instruction multiple data (SIMD) streams, and (b) multiple instruction multiple data streams (MIMD). This paper describes a model to simulate network traffic with the Connection Machine, a massively parallel SIMD computer. First we introduce the basic parallel computing architectures along with a list of commercially available parallel computers. It is followed by an in-depth presentation of the proposed simulation methodology with a massively parallel computer. The proposed traffic simulation model has an inherent path-processing capability to represent drivers' route choice behavior at the individual/vehicle level. Such a feature is critical to its integration with a real-time dynamic assignment model in IVHS applications. The proposed model has been implemented on the Connection Machine. Several simulation experiments were carried out which show that massively parallel computers provide a viable alternative for use in the real-time application. The results show that the CM-2 with 16,384 processors can simulate 32,000 vehicles for 30 minutes at a one-second interval within 3 1 2 minutes.

Performance Study of an ATM Self‐Routing Multistage Switch with Bursty Traffic: Simulation and Analytic Approximation

Abstract: An N x N self-routing multistage switching network with bursty and uniform traffic, which is composed of S x 5 switching elements with output queueing and has K = logS N stages, is considered in this paper. The input traffic is modelled by a two-state (active/silent) Markov chain. Each arriving cell selects one of the N outlets as its destination independently and with equal probability I/N. The performance of the switching network is studied by means of a simulation method. An approximate traffic model of a four-state Markov chain is proposed to characterize the cell arrival processes to further stages and its related switching element performance is analyzed. Comparison with the simulation results shows that the proposed traffic model gives a good approximation, which implies that the performance of the switching element mainly depends on the first two moments of the active and silent periods and is not sensitive to the shapes of their distributions. The influence of bursty traffic on the performance of the switching network is discussed and illustrated by some numerical examples. The impact of traffic randomization on the performance of the switching network is also investigated.

Transportation engineering and planning. second edition

Abstract: This book provides a good introduction to the subject of transport engineering. Separate sections are provided on: a) transportation modes; b) urban transportation; and c) traffic impact and transport studies. Transportation planning and traffic simulation software packages are also covered. These include demand forecasting models. Separate sections are also provided on: a) vehicle flow models; b) capacity analysis; c) flow interruptions at intersections; d) the evaluation of air, noise and energy impacts of transport. New sections have been included on highway geometry and pavement design. Regression modelling, and methods for hypothesis and model testing are discussed in Appendix C. Guidelines for the preparation of environmental assessment documents are given in Appendix A. Elements of engineering economy are presented in Appendix B.

Upgrading travel demand forecasting capabilities

Abstract: With the passage of the Intermodal Surface Transportation Efficiency Act of 1991 and the Clean Air Act Amendments of 1990, there is increased concern about the limitations of travel forecasting procedures to meet the requirement of these acts. Current travel forecasting models, in use for almost 30 years, were originally developed for long range regional scale planning and forecasting, especially for highways. This paper examines: (1) the requirements of a long-term development program to upgrade travel demand forecasting capabilities in transportation agencies; (2) the new Travel Model Improvement Program, which has just completed its first year; and (3) lessons learned from past experiences using travel forecasting procedures that should be applied in the development of a new generation of procedures.

Application of time series techniques for forecasting truck traffic attracted by the bombay metropolitan region

Abstract: Knowledge of futuree traffic flow is an essential input in the planning, implementation and development of a transportation system. It also helps in its operation, management and control. Time series analysis techniques have been extensively adopted for this purpose in the fields of economics, social sciences and in other fields of technology. An attempt has been made in this study to apply the techniques of time series analysis to goods traffic, particularly truck traffic. Four predominant corridors, accounting for majority of truck movement in the Bombay Metropolitan Region (BMR), have been considered for modeling. Raw data was processed initially, to obtain an insight into the structure of time series. Ten candidate models of the Auto-Regressive Moving Average (ARMA) and Auto-Regressive Integrates Moving Average (ARIMA) family are investigated to represent each of the four corridors. Models finally proposed have been selected based on Minimum Mean Square Error (MMSE) and Maximum Likelihood Rule (MLR) criteria.

Comparison of performance of twopas and trarr models when simulating traffic on two-lane highways with low design speeds

Abstract: A comparison of the TWOPAS and TRARR models when used to simulate traffic operation on two-way rural highways with low design speed and two lanes is reported on in this paper. It was found that the TWOPAS and TRARR models are generally comparable in their ability to simulate traffic operations on two-lane, two-way highways. However, the TWOPAS simulation results compared better with field data for roads with an 80-km/hr (50-mph) design speed. This was the case for both a level terrain site and a rolling terrain site. The comparison was made in travel time and percentage time delay. Both models require further work before they can be applied without reservation to the many types of situations that might arise on two-lane roads. It is recommended, however, that TWOPAS be adopted for analysis related to capacity and level of service.

Distributed/parallel traffic simulation for IVHS applications

Abstract: This paper presents two algorithms developed for a distributed, discretes-event, and object-oriented traffic simulation, such as the Raffle and Highway Objects for REsearch, Analysis, and Understanding (THOREAU) (McGurrin and Wang, 1991) and (Hsin and Wang, 1992). THOREAU was designed for the study and analysis of Intelligent Vehicle Highway Systems (IVHS) [1] applications. The purpose of using distributed processing for traffic simulation is to extend the scope which can be modeled at an individual vehicle behavior level, by significantly increasing execution speed. The first algorithm was derived to decompose a large traffic model into submodels distributed over a network of workstations, with a minimum amount of inter-processor interactions, and to achieve the highest degree of parallelism. The second algorithm is an improvement of the Floyd algorithm for finding shortest paths using submodel decomposition and node to are incidency to achieve a 10m/sup 3/- fold speed improvement using m distributed processors. Both algorithms are being implemented for IVHS-related applications in a new version of THOREAU.

Simulating network traffic flows with a massively parallel computing architecture

Abstract: This paper presents a traffic network simulation model for real-time applications in IVHS. The proposed model has incorporated three key features essential for IVHS operations: (1) the capability of simulating both freeways and surface street networks as an integrated network; (2) a path-processing capability for representing drivers' route choice behavior at an individual/vehicle level; and (3) the capability of simulating different subnetworks at different levels of detail so as to increase the execution speed for real-time operations. Three simulation methodologies are implemented in the real-time traffic simulation model to satisfy the above requirements. These three methodologies are macroparticle traffic simulation model (MPSM), modified NIPSM (M-MPSM), and microscopic (MICRO) model. Due to the real-time operating requirement, the proposed simulation model has been parallelized to take advantage of the parallel computers since they can offer the required computational power at an economical cost/performance ratio. Several simulation experiments have been carried out to compare the execution speed of each methodology. The preliminary research results indicate that parallel computing architecture offers a very promising alternative for the implementation of real-time traffic simulation.

Fast Low Fidelity Microsimulation of Vehicle Traffic on Supercomputers

Abstract: A set of very simple rules for driving behavior used to simulate roadway traffic gives realistic results. Because of its simplicity, it is easy to implement the model on supercomputers (vectorizing and parallel), where we have achieved real time limits of more than 4~million~kilometers (or more than 53~million vehicle sec/sec). The model can be used for applications where both high simulation speed and individual vehicle resolution are needed. We use the model for extended statistical analysis to gain insight into traffic phenomena near capacity, and we discuss that this model is a good candidate for network routing applications. (Submitted to Transportation Research Board Meeting, Jan. 1994, Washington D.C.)

Simulation Of IVHS On The Smart Corridor Using The Integration Model: Phase 1: Initial Investigations

Abstract: The general objective of this project is to evaluate the potential benefits of Advanced Traveler Information Systems and Advanced Traffic Management Systems on the Smart Corridor. This report describes Phase 1 of the project in which the INTEGRATION traffic simulation model is used to help simulate ATIS and ATMS on a freeway/arterial environment.

Traffic models overview handbook

Abstract: This Handbook provides an overview of a number of Traffic Models for performing traffic signal timing optimization mainly for arterials and networks and for performing evaluations of traffic operations and geometric design plans for intersections, arterials, urban street networks, and freeways using simulation models. The simulation models reviewed encompass both macroscopic and microscopic models. The purpose of the Handbook is to provide the transportation professional with information sufficient for deciding if a particular traffic model would be suitable for their applications and an idea on how much effort and resources would be required to apply the model effectively.

Development of a model-based framework for ivhs benefit analysis

Abstract: This paper describes the Volpe National Transportation Systems Center's proposed model-based framework for assessing the impacts of Advanced Traffic Management Systems (ATMS), Advanced Traveler Information Systems (ATIS), and Advanced Public Transportation Systems (APTS) techniques on congestion, vehicular emissions, fuel consumption, and safety. The framework will integrate selected ensembles of planning, traffic simulation, and benefit estimation models to assess the potential short- and long-term impacts of IVHS implementations.

Simulation of Advanced Traveller Information Systems (ATIS) Strategies to Reduce Non-Recurring Congestion from Special Events

Abstract: The design and implementation of Advanced Traveller Information Systems (ATIS) providing real-time enroute information to drivers should follow insightful analyses into the dynamics of driver decisions and the resulting traffic flow under information to prevent counter-intuitive and counter-productive results. An important yet often neglected aspect of this problem is the distribution of benefits both over the driver population and for different origins and destinations in the network. This paper presents modifications to and an application of DYNASMART (DYnamic Network Assignment Simulation Model for Advanced Road Telematics) for this problem. DYNASMART is a simulation framework for ATIS experiments which incorporates: 1) real-time traffic flow and control simulation, 2) dynamic network path processing, and 3) microscopic consideration of driver response to information. A boundedly-rational behavioral model is assumed for driver route-choice under non-prescriptive route information. The information strategies are based on multiple paths rather than a single shortest path. Initial paths of drivers were generated from dynamic equilibrium assignments using the CONTRAM program and used as input to DYNASMART. ATIS-equipped drivers change their paths based on a behavioral model (with stochastically assigned parameters) and provided information, while unequipped drivers change routes based on self-observation of traffic conditions. The application presented involves the evaluation of ATIS strategies to alleviate traffic congestion due to spectators leaving a major sports event at Anaheim Stadium. A dynamic traffic demand matrix was estimated from partial link-counts. Interesting insights are derived regarding the higher benefits from ATIS to drivers on congested parts of the network. Robustness of the benefits under various information supply strategies and behavioral scenarios are also discussed.

Modeling autonomous agents in a knowledge based simulation environment

Abstract: Raod users in the traffic world make up a system of autonomous acting agents. Understanding and describing the phenomena of the traffic world raises questions in the field of distributed artificial intelligence. The authors implemented the traffic simulation environment ISYS to develop and test strategies and concepts for driver models and innovative driver assistant systems. The simulation environment provides a framework to model/construct autonomous agents individually and with models of different granularity. It integrates knowledge-based techniques with numerical methods for simulation of vehicle dynamics. An application example demonstrates the interactions among different agents simulated with ISYS.

The Integration of the Highway Capacity Manual and the TRAF-NETSIM Simulation Model

Abstract: The Bureau of Traffic Operations, New York City Department of Transportation (NYCDOT) utilizes for various types of studies and capacity analyses, the 1985 Highway Capacity Methodology and links the results from the analyses with the TRAF-NETSIM traffic simulation model. This is presently done by using the HCM/CINEMA computer program (a registered trademark of KLD Associates Inc. and Polytechnic University, New York). This paper describes how the program was used in a real 'case study' by the Bureau of Traffic Operations to evaluate traffic conditions prior to implementing any changes to the local street system. The program has been a valuable tool for the traffic engineers, assisting them in implementing detour alternatives and also recommending the appropriate modifications in the traffic signal cycle lengths, sequences and splits.

Regression-based urban arterial road delay models

Abstract: During the last two decades, emphasis in transportation planning has shifted from long-term capital-intensive construction projects to short- and medium-term, relatively low capital cost, projects ...

Pacific rim transtech conference proceedings. volume i. modeling route guidance systems using the integration model

Abstract: The in-vehicle Route Guidance Systems could be a cost effective means of alleviating the impact of traffic congestion in urban areas. The enhancements and extensions are described of the integration traffic simulation model's features for representing the routing behavior of vehicles having varying levels of access to RGS, different system architectures, and different routing objectives. Various tools for modeling the routing behavior and response of non-guided background vehicles are demonstrated. The behavior and performance of a number of different vehicle types are demonstrated on a test network of 2000 links for Warren, Michigan. A sensitivity analysis is made of the travel time benefits of the TravTek route guidance logic, with respect to market penetration level.

Simulation of ivhs strategies on the smart corridor

Abstract: A study is currently being conducted at the University of California at Berkeley as part of the California PATH Program to investigate and quantify the likely benefits of implementing various ATMS and ATIS control strategies such as freeway ramp metering, real-time traffic signal optimization, and route guidance systems on the Smart Corridor in Los Angeles. In order to address these questions, a modeling approach was selected. The INTEGRATION traffic model, developed at Queen's University in Kingston, Canada, was used for this application, as several characteristics of this model make it a powerful and rather unique tool for network analysis in the IVHS context. This paper goes on to describe the development of a reference base run representing typical traffic conditions on the Smart Corridor during the morning peak period. Subsequently, the effects of introducing freeway ramp metering control, traffic signal optimization, route guidance systems, and combinations of these strategies, are examined and discussed.

Microcomputers in transportation. use of traf-netsim to estimate the traffic impacts of an urban-resort area development

Abstract: The TRAF-NETSIM model is applied to the estimation of the expected traffic impacts associated with a proposed hotel expansion in the urban resort district in Waikiki, Honolulu, Hawaii The model was used in addition to a traditional analysis based on the Highway Capacity Manual in order to explicitly address persisting concerns raised by the surrounding residential community Among concerns were the impact of city buses, tour buses unrelated to the proposed project, and tour bus operations serving the hotel complex The advantages of using an area-wide simulation model to address such concerns when preparing environmental impact statements is illustrated, and the way conditions not directly supportable by TRAF-NETSIM were supported, is described

Integration - a critique

Abstract: A study of the INTEGRATION traffic simulation model was conducted. In particular, the theory and procedures used by the model were studied and evaluated in detail, with special emphasis on the model's uses of traffic assignment. The paper provides: -an overview of INTEGRATION's simulation procedures. -discussions of its relative strengths and weaknesses. -a brief discussion of some subsequent developments on INTEGRATION. It was concluded that: -INTEGRATION is quite user-friendly for a model of this type. -the assignment and simulation sub-models within INTEGRATION need to interact more. -the assignment model needs to learn how to better use the information from the simulation side, and to incorporate an iterative capability to facilitate this. -individual vehicle simulation is inefficient, as iterations should be used. It is recommended that: -a rate-based procedure be used in order to provide pre-estimates of equilibrium routings and link costs; -a routine be added to keep track of the front and tail of queues.

A real-time network traffic simulation model for atms applications

Abstract: This paper presents a traffic network simulation model for real-time applications in Intelligent Vehicle Highway Systems (IVHS). The proposed model has incorporated three key features essential for IVHS operations: 1) the capability of simulating both freeways and surface street networks as an integrated network; 2) a path-processing capability for representing drivers' route choice behavior at an individual/vehicle level; and 3) the capability of simulating different subnetworks at different levels of details so as to increase the execution speed for real-time operations.

Simulation of ATIS Strategies to Mitigate Special Event Congestion

Abstract: This research extends the performance and application of DYNASMART, a dynamic traffic simulation model which incorporates the three elements necessary for modeling traffic flow under information: (1) real-time traffic flow simulation, (2) dynamic path processing, and (3) microscopic consideration of the response of individual drivers to information DYNASMART performs real-time modeling of traffic flow in which a specified percentage of vehicles are equipped with In-Vehicle Navigation Systems (IVNS) The CONTRAM assignment program is used to provide DYNASMART with realistic dynamic equilibrium routes for the initial path assignment of unequipped vehicles The special-event traffic scenario, characterized by intense, short-term, nonequilibrium congestion in the presence of many alternative routes, is an ideal candidate for early and successful deployment of IVNS The network and traffic demand of Anaheim, California are modeled with special events traffic generated by Anaheim Stadium A dynamic Origin-Destination matrix was estimated using the COMEST program and observed link counts