Showing papers on "Intelligent transportation system published in 1994"

Short-term traffic flow prediction: neural network approach

Abstract: Much of the current activity in the area of intelligent vehicle-highway systems (IVHSs) focuses on one simple objective: to collect more data. Clearly, improvements in sensor technology and communication systems will allow transportation agencies to more closely monitor the condition of the surface transportation system. However, monitoring alone cannot improve the safety or efficiency of the system. It is imperative that surveillance data be used to manage the system in a proactive rather than a reactive manner. Proactive traffic management will require the ability to predict traffic conditions. Previous predictive modeling approaches can be grouped into three categories: (a) historical, data-based algorithms; (b) time-series models; and (c) simulations. A relatively new mathematical model, the neural network, offers an attractive alternative because neural networks can model undefined, complex nonlinear surfaces. In a comparison of a backpropagation neural network model with the more traditional approaches of an historical, data-based algorithm and a time-series model, the backpropagation model was clearly superior, although all three models did an adequate job of predicting future traffic volumes. The backpropagation model was more responsive to dynamic conditions than the historical, data-based algorithm, and it did not experience the lag and overprediction characteristics of the time-series model. Given these advantages and the backpropagation model's ability to run in a parallel computing environment, it appears that such neural network prediction models hold considerable potential for use in real-time IVHS applications.

Vision-based vehicles in Japan: machine vision systems and driving control systems

Abstract: This paper surveys three intelligent vehicles developed in Japan, and in particular the configurations, the machine vision systems, and the driving control systems. The first one is the Intelligent Vehicle, developed since the mid 1970's, which has a machine vision system for obstacle detection and a dead reckoning system for autonomous navigation on a compact car. The machine vision system with stereo TV cameras is featured by real time processing using hard-wired logic. The dead reckoning function and a new lateral control algorithm enable the vehicle to drive from a starting point to a goal. It drove autonomously at about 10 km/h while avoiding an obstacle. The second one is the Personal Vehicle System (PVS), developed in the late 1980's, which is a comprehensive test system for a vision-based vehicle. The machine vision system captures lane markings at both road edges along which the vehicle is guided. The PVS has another machine vision system for obstacle detection with stereo cameras. The PVS drove at 10-30 km/h along lanes with turnings and crossings. The third one is the Automated Highway Vehicle System (AHVS) with a single TV camera for lane-keeping by PD control. The machine vision system uses an edge extraction algorithm to detect lane markings. The AHVS drove at 50 km/h along a lane with a large curvature. >

Traffic at the edge of chaos

Abstract: We use a very simple description of human driving behavior to simulate traffic. The regime of maximum vehicle flow in a closed system shows near-critical behavior, and as a result a sharp decrease of the predictability of travel time. Since Advanced Traffic Management Systems (ATMSs) tend to drive larger parts of the transportation system towards this regime of maximum flow, we argue that in consequence the traffic system as a whole will be driven closer to criticality, thus making predictions much harder. A simulation of a simplified transportation network supports our argument.

Dynamic Urban Transportation Network Models: Theory and Implications for Intelligent Vehicle-Highway Systems

Abstract: Contents: Dynamic Transportation Network Analysis.- Mathematical Background.- Deterministic Dynamic Route Choice.- Stochastic Dynamic Route Choice.- General Dynamic Travel Choices.- Variational Inequality Models.- Implications for IVHS.

Roadside intelligence for flow control in an intelligent vehicle and highway system

Abstract: The paper reports a design of the flow control function of the highly automated Intelligent Vehicle Highway System that we call SmartIVHS. Work on the architecture, design, experiments, and performance evaluation of this system has been going on for several years. SmartIVHS achieves high throughput and safety through a three-layer control hierarchy distributed between vehicles and infrastructure. Previous work was devoted to the two lowest layers: automatic control of individual vehicles based on on-board sensor information, and coordination of maneuvers by neighboring vehicles. This paper considers the third or ‘link layer,’ which controls the vehicle stream based on aggregate traffic variables. The link layer controller is implemented by roadside computers. The two lowest layers are implemented by vehicle computers. The paper is divided into three parts. First, a structure of the link layer controller is proposed. Its objectives are to maximize throughput and to maintain smooth traffic flow despite disturbances, including lane-blocking incidents. The objectives are met by proper guidance of the speed and lane-changing behavior of vehicles. Second, a macroscopic flow model of SmartIVHS traffic is proposed. A novel feature is the explicit incorporation of the effects of lane changes, entrances, and exits. The program SmartLink simulates this model. Third, performance of the link layer controller is evaluated using SmartLink. The results suggest that the controller maximizes throughput and minimizes delay in the presence of disturbances and incidents.

Traffic assignment under environmental and equity objectives

Abstract: Two recent changes in the transportation field may have a profound effect on traffic assignment techniques. The first is the increasing importance of environmental objectives, such as reducing air pollution, within the policies of traffic system authorities. The second change is the advent of the intelligent vehicle-highway system (IVHS), which, among other attributes, has the potential to be used to implement new methods of controlling vehicular emissions. The fact that historic traffic assignment techniques may be inadequate for modeling the traffic systems that will operate under IVHS with environmental objectives--primarily when the traffic follows routes that are based on equitable rather than equilibrium or optimal considerations--is illustrated. Then it is shown that when IVHS policies that attempt to reduce system travel time are implemented, other objectives such as reducing environmental pollution may actually increase. A network from Ottawa, Ontario, Canada, is used as a test bed.

Vehicle location and tracking for IVHS in CDMA microcells

Abstract: This paper discusses the use of mobile cellular radio networks for providing vehicle location information to intelligent vehicle/highway system (IVHS) services. We review various automatic vehicle location (AVL) techniques in context to their application in a direct-sequence code-division multiple-access (DS/CDMA) system, in particular, the EIA/TIA/IS-95 standard proposed by Qualcomm Inc. A new matched filter location technique which is suited to the CDMA environment is discussed along with simulated error statistics and recommendations for improvement. We also consider network loading effects in terms of Signaling System 7 (SS7).

Metacor: a macroscopic modelling tool for urban corridor

Abstract: This paper describes a new integrated macroscopic modelling tool namely "METACOR" for simulating traffic flow phenomena including traffic assignment modelling within mixed network (motorway and urban road subnetworks) of arbitrary topology. METACOR has been validated on the basis of real traffic flow measurements selected under a broad spectrum of traffic conditions. The mathematical model is capable of describing complicated traffic phenomena with acceptable accuracy. A simulation program may be used as a tool for testing of control strategies related to ramp metering, signal control and Variable Message Sign (VMS) control. (A) For the covering abstract see IRRD 868006.

Examination of intersection, left turn across path crashes and potential ivhs countermeasures

Abstract: The report provides a preliminary analysis of intersection-related, left turn across path (LTAP) crashes and applicable countermeasure concepts for the Intelligent Vehicle Highway System (IVHS) program. An LTAP crash occurs when the subject vehicle approaches an intersection, attempts to turn left, and either strikes or is struck by the principal other vehicle traveling in the opposite traffic lanes. The crash avoidance system (CAS) concepts discussed in this report include driver warnings, partially automatic vehicle control systems, and fully automatic vehicle control systems. This report concludes with a number of research needs to better understand LTAP crashes and guide CAS development.

Criteria and methods for evaluating intelligent transportation system plans and operational tests

Abstract: An evaluation process for the preparation of intelligent transportation system (ITS) plans that is sensitive to the differences between ITS and conventional transportation improvements is described. A relatively complete set of evaluation criteria for ITS improvements is presented that is structured to clarify the confusion between the supply and demand impacts of ITS. This separation between "efficiency" and "output" measures means that it is possible to distinguish between ITS technology efficiency benefits and the individual and corporate demand responses to ITS that actually increase output (benefits) over those produced by the technology alone. The proposed criteria structure also incorporates the time scale of the impacts. This highlights certain fundamental correlations between the criteria that can lead to double counting of benefits and to highly correlated outcomes, which are not helpful in choosing between alternatives. The criteria structure facilitates selection by decision makers of greatly reduced criteria sets to simplify ITS evaluations. By recognizing the separate supply (efficiency) and demand (increased output) impacts of ITS, it is also possible to avoid dramatically underestimating the benefits of the new technology and to avoid serious mistakes in assessing the safety, environmental, and energy impacts of ITS alternatives. Default values to evaluate ITS improvements for inclusion in transportation system plans are provided. The criteria and default values highlight where research and operational tests can provide improved values and information that will most quickly advance the state of the art of ITS evaluation.

The automated highway system: an idea whose time has come

Abstract: This article describes the Automated Highway System (AHS) program, which in the future will make highway driving efficient, safe, and predictable. Research on the new intelligent vehicle-highway system reveals that traffic congestion will be reduced, a collision-free highway system will be produced through enhanced safety, and driving will become more predictable and reliable. The article provides information about AHS technologies that make AHS possible, program progress to date, and future demonstrations of the system. AHS program officials are investigating human factors of the system as well. A preliminary handbook that addresses driver issues that relate to AHS design will be available in 1994 with a second edition available in 1996. A national AHS consortium of public and private sector representatives will guide the Department of Transportation in administering this program.

Advanced Technology for Road Transport: IVHS and ATT

Abstract: From the Publisher: Better understand the application of telematics to road transport, including the latest ITS/ATT developments in the US, Europe, and Japan with this book. It concentrates on key developments in road transport technology, particularly on advances that will affect the way in which people travel over the next decade.

Radar based automotive obstacle detection system

Abstract: This paper highlights a radar-based obstacle detection system developed by the Daimler Benz group to assist the driver, particularly in dangerous traffic situations and in bad weather. Special attention is given to vehicle test data evaluation based on a mobile video system operating in the traffic environment and data post-processing in the lab.

A planning methodology for intelligent urban transportation systems

Abstract: Recent developments in intelligent transportation systems pose new challenges and opportunities for urban transportation planning. To meet these challenges and to exploit these opportunities, a framework for a new transportation planning methodology has been developed. The methodology operates in a computer environment, called PLANiTS (Planning and Analysis Integration for Intelligent Transportation Systems), designed to facilitate the entire planning process form problem identification, through idea generation and analysis, on to prioritization and programming. To assist in problem identification, PLANiTS provides graphic representation of current conditions, including traffic, air pollution, accidents, and projections of future conditions. A computerized knowledge base, containing information about possible strategies and their effects, and a model base, containing transportation and other analysis models, are used to guide the user in identifying potentially effective strategies and performing the appropriate analysis. To facilitate the use of these tools, PLANiTS provides computer support of group processes such as brainstorming, deliberation, and consensus seeking. PLANiTS is designed for use in urban transportation planning at the local, regional, and state levels; it is intended to support a variety of participants in the planning process including transportation professionals, decision makers in transportation agencies (often local elected officials), citizens, and interest groups. Recognizing that transportation planning is essentially a deliberative, political process, PLANiTS is designed to inform and facilitate, but not replace, the political decision-making process.

A Reusability Study of Vehicle Lateral Control System

Abstract: SUMMARY The architecture of the PATH vehicle lateral control system is presented in this paper. The two main modules are an intelligent reference/sensing system, and an Frequency-Shaped-Linear-Quadratic/preview control algorithm. The whole lateral control system was formerly evaluated on a two-door test vehicle. It was transplanted to a four-door vehicle which is considerably different from the older two-door test vehicle in dynamic characteristics. The objective of this study is to investigate the reusability of our control system.

Framework for evaluating intelligent vehicle-highway systems

Abstract: Evaluation of intelligent vehicle-highway systems (IVHSs) is a relatively new activity. An evaluation framework useful for those interested in IVHSs is presented in which each component of IVHS evaluation offers new challenges. These challenges involve public and private benefits, new product functions, market penetration, abundant data generated from new systems, human interaction, and multisite deployments. Although many methodologies for evaluation exist, some significant challenges need to be addressed to properly evaluate IVHSs.

Development of a model to assess the safety impacts of implementing ivhs user services

Abstract: This paper describes the design of a safety model that was developed to assess how the number and severity of accidents in a network are affected by the implementation of IVHS (Intelligent Vehicle-Highway Systems) user services. Facility type, geometric design, degree of congestion, number of stops and speed variability are factors that may affect safety. Implementation of some IVHS user services may impact the number and severity of accidents in a network by redistributing traffic to different facility types and/or to facilities with different levels of congestion. The model framework was developed to assess the congestion, emissions, fuel consumption and safety benefits of implementing IVHS user services. This paper focuses on the design of the safety model and not on evaluating the user services.

Dyna: a real-time monitoring and prediction system for inter-urban motorways

Abstract: The goal of DYNA, an EC DRIVE II project, is to build and evaluate an on-line monitoring and prediction system for inter-urban motorway networks. The paper describes the system architecture, which comprises two dynamic representations of the network traffic process: O/D flows and link densities reflecting both choice behaviour and traffic flow physics. Predictions on the traffic state, with a rolling horizon of up to 60 minutes, is output to the traffic operator. The paper describes the pilot application in which the models are tested and the overall evaluation of the complete system; it ends with a discussion of intra-urban and control extensions. (A) For the covering abstract see IRRD 868006.

Case Studies of Market Research for Three Transportation Communication Products

Abstract: The following is one of a series of papers developed or produced by the Economic Analysis Division of the John A. Volpe National Transportation Systems Center as part of its research project looking into issues surrounding user response and market development for selected Intelligent Vehicle-Highway Systems (IVHS) products or services. The project, sponsored by the Federal Highway Administration's Office of Policy Development, was one part of FHWA's 1992 Institutional Issues Program entitled-" Public Acceptance and Markets for Various Consumer IVHS Services ". John O'Donnell of the Volpe Center and James March of FHWA served as Project Managers for their organizations. The objective of the Volpe Center project was to better understand factors affecting the development and deployment of selected advanced traveler information products and services (ATIS). The Center addressed the objective by examining the development of markets for selected ATIS-related products and services and reviewing factors affecting the public acceptance and user response to existing traffic information services. Deployment of many of the newly emerging and projected M-IS products and services will depend upon consumers purchasing and otherwise choosing to make use of advanced traffic and travel information products and services. Through four different projects, each with a distinctive approach to understanding consumer response and market demand, the Volpe Center explored the question: Given the opportunity to buy a product or subscribe to a service that promises to deliver traveler information, will the consumer perceive that there is sufficient benefit to be gained to justify the investment? The Volpe Center and FHWA jointly conducted a workshop in the Fall of 1992 to discuss issues involved with assessing the market for IVHS products and services. The objectives of the workshop were to help define a research program which would address measuring user acceptance and response to ATIS products and services and the role market research plays in understanding emerging markets for new or unknown products and services. The results of the workshop are reflected in the four research tasks initiated as part of this program and the seven papers which comprise it. The four task areas are summarized below. Copies of the papers will be provided upon request to the Volpe Center. The first project was designed to answer the question of how consumer response and market demand are measured in the commercial sector, where these market demand questions are fundamental to the survival and success of the business. This project …

An advanced real-time ramp metering system (arms): the system concept

Abstract: This research report presents a three-level, highway ramp-metering control scheme. In the first level, ramp controllers distributively compute ramp metering rates based on system-wide information. The system adapts quickly to changing traffic conditions; it is modular and allows scalable and robust implementation. The O-D prediction algorithm is adaptive and very accurate. The second level consists of an optimal, self-learning, congestion predictor algorithm that may predict all short-term traffic flow-breakdowns. The algorithm, using self-learning, utilizes sequences of traffic patterns to improve its prediction accuracy. The third level is a congestion resolution scheme which overcomes many of the drawbacks of existing techniques. It balances the congestion resolution time with the service quality of the surface streets. Simulation results show that application of the three-level control algorithm will improve the freeway and surface street service.

The use of gps in travel-time surveys

Abstract: Travel-time surveys have long been used to provide performance data for the assessment of traffic systems. The traditional methods of finding the amount of travel time have been difficult to apply and sometimes provided only limited informartion.This article discusses the Global Positioning System (GPS) and the benefits it provides for transportation data collection. Not only will it benefit data collection in travel-time surveys but other areas dealing with transportation issues will also gain, e.g. road asset management, Intelligent Vehicle Highway Systems, and real-time vehicle tracking, among others.