Showing papers in "PATH research report in 1998"

Intelligent Cruise Control Systems and Traffic Flow Stability

Abstract: In analogy to the flow of fluids, it is expected that the aggregate density and the velocity of vehicles in a section of a freeway adequately describe the traffic flow dynamics. The conservation of mass equation together with the aggregation of the vehicle following dynamics of controlled vehicles describes the evolution of the traffic density and the aggregate speed of a traffic flow. There are two kinds of stability associated with traffic flow problems - string stability (or car-following stability) and traffic flow stability. We make a clear distinction between traffic flow stability and string stability, and such a dis- tinction has not been recognized in the literature, thus far. String stability is stability with respect to intervehicular spacing; intuitively, it ensures the knowledge of the position and velocity of every vehicle in the traffic, within reasonable bounds of error, from the knowledge of the position and velocity of a vehicle in the traffic. String stability is analyzed without adding vehicles to or removing vehicles from the traffic. On the other hand, traffic flow stability deals with the evolution of traffic velocity and density in response to the ad- dition and/or removal of vehicles from the flow. Traffic flow stability can be guaranteed only if the velocity and density solutions of the coupled set of equa- tions is stable, i.e., only if stability with respect to automatic vehicle following and stability with respect to density evolution is guaranteed. Therefore, the ow stability and critical capacity of any section of a highway is dependent not only on the vehicle following control laws and the information used in their synthesis, but also on the spacing policy employed by the control system. Such a dependence has practical consequences in the choice of a spacing policy for adaptive cruise control laws and on the stability of the traffic ow consisting of vehicles equipped with adaptive cruise control features on the existing and future highways. This critical dependence is the subject of investigation in this paper. This problem is analyzed in two steps: The first step is to understand the effect of spacing policy employed by the Intelligent Cruise Control (ICC) systems on traffic flow stability. The second step is to understand how the dynamics of ICC system affects traffic flow stability. Using such an analysis, it is shown that cruise control systems that employ a constant time headway policy lead to unacceptable characteristics for the traffic flows. Key Words: Intelligent Cruise Control Systems, Traffic Flow Stability, String Stability, Advanced Vehicle Control Systems, Advanced Traffic Management Systems.

Evaluation of the Freeway Service Patrol (FSP) in Los Angeles

Abstract: This report presents the results of a study designed to evaluate the effectiveness of the freeway service patrols (FSP) on a section of I-10 in Los Angeles. An evaluation methodology was used to estimate incident delays based on loop detector data and probe vehicles, and derive estimates of savings in performance measures in the absence of data for before FSP conditions. The estimated benefit cost ratios based on delay and fuel savings for a range of typical reductions in incident durations indicate that FSP produces significant benefits at the test site. Additional benefits include reductions in air pollutant emissions, secondary accidents, highway patrol time used on non-enforcement activities, increased safety to assisted motorists, and more efficient operation of the freeway system.

The I-880 Field Experiment: Effectiveness Of Incident Detection Using Cellular Phones

Abstract: This report describes the evaluation of the effectiveness and adequacy of cellular phones for incident detection as an alternative to infrastructure-based surveillance systems. The analysis was conducted as part of the I-880 field experiment using the California Highway Patrol's (CHP) Computer Aided Dispatch (CAD) incident database. Cellular phones have the highest detection rate among the detection sources examined. They detect 38% of the freeway incidents (accidents and lane-blocking disablements). The combined cellular phones, freeway service patrol (FSP) and the CHP detect 75% of all incidents. The results from the statistical analysis indicate a significant effect of the incident detection source on the incident duration. Incidents reported by cellular phones show greater incident durations by an average of 14 minutes than similar incidents reported by the CHP or the FSP. This additional delay is due to the incident verification process.

Modeling The Santa Monica Freeway Corridor: A Feasibility Study

Abstract: This report presents the findings of a feasibility study which developed a simulation testbed for the Santa Monica freeway corridor. The study involved performing an evaluation of the state-of-the-art models for Advanced Traffic Management and Traffic Information Systems (ATMIS) on freeway corridors. The evaluation was based on the model capabilities, input data requirements and output options, with focus on the record of real-life calibration, validation and practical application of the models. The findings show that the CORSIM and INTEGRATION models have the higher probability of successful application in real-world applications.

Drag Forces Experienced by Two, Full-Scale Vehicles at Close Spacing

Abstract: The present study aims to document the drag reduction for a two-vehicle platoon by operating two full-scale Ford Windstar vans in tandem on a desert lakebed Drag forces are measured with the aid of a special tow bar force measuring system designed and manufactured at USC The testing procedure consists of a smooth acceleration, followed by a smooth deceleration of the platoon Data collected during acceleration allows the calculation of the drag force on the trail-vehicle, while data collected during deceleration is used to calculate the drag on the lead vehicle Results from the full-scale tests show that the drag behaviors for the two vans are in general agreement with the earlier conclusions drawn from the wind tunnel tests--namely, both vans experience substantial drag savings at spacings of a fraction of a car length

Final Report: City of Anaheim/Caltrans/FHWA Advanced Traffic Control System Field Operational Test Evaluation Task C, Video Traffic Detection System

Abstract: CALIFORNIA PATH PROGRAM INSTITUTE OF TRANSPORTATION STUDIES UNIVERSITY OF CALIFORNIA, BERKELEY City of Anaheim/Caltrans/FHWA Advanced Traffic Control System Field Operational Test Evaluation: Task C Video Traffic Detection System Art MacCarley California Polytechnic State University, San Luis Obispo California PATH Research Report UCB-ITS-PRR-98-32 This work was performed as part of the California PATH Program of the University of California, in cooperation with the State of California Business, Transportation, and Housing Agency, Department of Transportation; and the United States Department of Transportation, Federal Highway Administration. The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the State of California. This report does not constitute a standard, specification, or regulation. Final Report for RTA 65V313-4 September 1998 ISSN 1055-1425 CALIFORNIA PARTNERS FOR ADVANCED TRANSIT AND HIGHWAYS

Longitudinal Control Of Heavy Duty Vehicles: Experimental Evaluation

Abstract: This report describes the results of experimental evaluation of longitudinal control algorithms for commercial heavy vehicles (CHVs). Given the problem of delays in the fuel and brake actuators of automated CHVs, the researchers present improved modeling of air brakes for CHVs, and novel nonlinear algorithms for the longitudinal control of CHVs without intervehicle communication. The significance of these results in terms of Intelligent Transportation Systems (ITS) deployment is that one of the major obstacles to autonomous vehicle following for CHVs has now been removed The authors also point out that adaptive cruise control can now be implemented in CHVs that are not equipped with Electronic Brake Systems.

GPS/INS Based Lateral and Longitudinal Control Demonstration: Final Report

Abstract: This report describes the results of a study focusing on implementing and analyzing the performance of a Differential Global Positioning System (DGPS) aided Inertial Navigation System (INS) for possible future application in Advanced Vehicle Control Systems (AVCS) The DGPS/INS system provided estimates of vehicle position, linear velocities, and angular rates Position accuracy at the centimeter level was achieved and demonstrated through two experiments

Analysis, Design, And Evaluation Of Avcs For Heavy-duty Vehicles With Actuator Delays

Abstract: This report focuses on the design of longitudinal control algorithms for commercial heavy vehicles (CHVs). The algorithms use nonlinear spacing policies, backstepping control design, and aggressive prediction schemes to deal with the presence of significant delays and saturations in the fuel and brake actuators. The algorithms can also deal with delays both in the presence and in the absence of intervehicle communication. A by-product on this research is the development of two software packages, Platoon-Builder and TruckVis, for simulation and animation of CHV platoons. Additionally, another important result of this project is a new simplified framework for evaluating the longitudinal string stability properties of platoons of automated vehicles.

Section Related Measures of Traffic System Performance: Final Report

Abstract: This project describes a new set of advanced traffic surveillance techniques that are based on inductive vehicle waveforms and pattern recognition technology. Focus is on demonstrating and evaluating a new method for obtaining true selection related performance measures, such as section travel time and section density, for freeways. The report also discusses methods for the measurement of lane-by-lane traffic movement and specific origin/destination demands.

Evaluation Of Mixed Automated/manual Traffic

Abstract: The advance in research and development will make the deployment of automated vehicles a reality in the near future. The principal question is whether these technologies will lead to any benefits in terms of safety, capacity and traffic flow characteristics as they penetrate the current transportation system. Another aspect is how to exploit these technologies in order to achieve benefits without adversely affecting the efficiency of the current transportation system and the drivers who cannot afford them. The penetration of automated vehicles into the existing transportation system will lead to mixed traffic where they will coexist with manually driven vehicles. The controversial class is where automated vehicles are allowed to mix with manually driven vehicles. The motivation behind this concept is that the current roadway will not have to undergo any major changes. Vehicles will become more and more automated independent of AHS and should have the ability to operate in lanes with manually driven vehicles. As the number of automated vehicles increases, the benefits of automation will increase until saturation, where all vehicles will be automated in the same way with cruise control, air-bags, etc. At the initial stage, vehicles will be semi-automated with the capability to follow each other automatically in the same lane. These semi-automated vehicles will coexist with manually driven vehicles on the same roadway system. The purpose of this report is to analyze the requirements, issues and effects on safety and efficiency that will result from allowing semi-automated and fully-automated vehicles to operate on the existing highway system together with manually driven vehicles. Two scenarios are considered : in the first scenario no changes are assumed for the current roadway system. In the second scenario it is assumed that the roadway controls the flow of traffic by issuing speed commands to both automated and manual vehicles. The roadway communicates via a roadway/vehicle communication with the automated vehicles system and through variable message signs with the manually driven vehicles. It is found that a number of safety and human factors issues present in both scenarios need to be resolved and studied further before mixing of semi-automated/fully-automated vehicles with manual ones becomes possible. Full automation will eliminate the driver out of the driving loop which will have serious safety implications some of which are raised and analyzed. In addition the interaction of fully automated vehicles with manual ones pose several safety problems due to the unpredictable behavior of the drivers of the manual vehicles. The effects on capacity with respect to the percentage of semi-automated vehicles penetrating the system and the derating factor due to possible lane changes are analyzed. Theoretically as the percentage of semi-automated vehicles increases, capacity also increases in most cases due to the shorter headways of the semi-automated vehicles. In practice this may not be always the case due to the unpredictability of the manually driven vehicles and the randomness of the headway used by different drivers which may further change due to presence of the semi-automated vehicles. Simulations reveal that significant improvement in the traffic flow can be achieved with a high degree of penetration of fully-automated vehicles in mixed traffic. Effects of lane- changing of fully-automated vehicles on mixed traffic capacity are analyzed. The lane- change derating factor is quantified as a function of market penetration of fully-automated vehicles for different percentages of automated vehicles changing lanes. One of the significant findings of this research is that a single semi-automated/fully- automated vehicle may attenuate large disturbances caused by rapid accelerations/decelerations and prevent the slinky effect from propagating. This attenuation is shown to take place without any effect on the travel time. The stopping of the propagation of large acceleration/deceleration transients by the automated vehicle will have positive effects on fuel consumption and pollution. KEYWORDS Automated Highway Systems (AHS), Semi-automated Vehicle, Fully- automated/Automated Vehicle, Manual/Manually driven Vehicle, Intelligent Cruise Control (ICC), Frontal Collision Warning System (FCW), Frontal Collision Avoidance System (FCA), Variable Message Signs (VMS), Roadway/Vehicle Communication System (RVCS), Degree of Penetration, Throughput, Headway, Merge Derating Factor, Slinky-effect, Sensors, Actuators, Vehicle-to-Vehicle Communication, Zone of Relevance, Global Positioning System (GPS), Minimum Safety Spacing (MSS)

Estimating ATIS Benefits for the Smart Corridor

Abstract: This report studies the effects of Advanced Traveler Information Systems (ATIS) on traffic congestion in the Smart Corridor of the Santa Monica Freeway. Simulation modeling is used to estimate the potential travel time savings to divert traffic from the Smart Corridor to arterial roads when incidents occur. The study attempts to establish relationships between traffic management variables, such as incident detection time, incident duration, capacity reduction, percentage of traffic diversion, and duration of traffic diversion.

Development And Experimental Evaluation Of Autonomous Vehicles For Roadway/vehicle Cooperative Driving

Abstract: Automatic vehicle following is an important feature of a fully or partially automated highway system (AHS). The on-board vehicle control system should be able to accept and process inputs from the driver, the infrastructure and other vehicles, perform diag- nostics and provide the appropriate commands to actuators so that the resulting motion of the vehicle is safe and compatible with the AHS objectives. The purpose of this paper is to design and test a vehicle control system in order to achieve full vehicle automation in the longitudinal direction for several modes of operation, where the infrastructure manages the vehicle following. These modes include autonomous vehicles, cooperative vehicle following and platooning. The vehicle control system consists of a supervisory controller that processes the inputs from the driver, the infrastructure, other vehicles and the on-board sensors and sends the appropriate commands to the brake and throttle controllers. In addition, the controller makes decisions about normal, emergency and transition operations. Simulation results of some of the basic vehicle following maneu- vers are used to verify the claimed performance of the designed controllers. Experiments on I-15 that demonstrate the performance of the throttle controller with and without vehicle-to-vehicle communications in an actual highway environment are also included. Keywords: Vehicle Control, Automated Highway Systems, Automatic Vehicle Following, Supervisory Control.

The Aerodynamic Forces On Misaligned Platoons

Abstract: This report summarizes wind tunnel experimental measurementson the aerodynamic interaction between members of misaligned platoons. Experiments are conducted at the University of Southern California's Dryden Wind Tunnel Facility. All experiments are made using 1/8 scale models of 1991 Chevy Lumina minivan. Models are placed above a ground plane with a porous surface, through which slight suction is applied to remove the boundary layer. Refurbishing of the ground plane surface, and its repositioning to a 1 degree angle of attack produce significantly improved air flow through the test section. Automatization of the testing procedures allow measurements of drag, side force and yawing moment with extremely fine position resolution. The measured quantities are presented in the form of coefficient ratios by ratioing the forces and moment with the value of drag experienced by a vehicle in isolation. The results of two separate experiments are presented in this report. First, aerodynamic forces on misaligned three-vehicle platoons are presented for all possible platoon configurations resulting from a longitudinal separation range of 0 to 0.72 vehicle lengths and a lateral displacement range of 0 to 1.1 vehicle widths for the middle vehicle. Results are presented in the form of color maps of the drag, side force and yawing moment coefficient ratios for each individual vehicle in the platoon. Experimental results from a complete set of symmetric configurations and five sets of non-symmetric configurations, associated with five fixed separations between the leading vehicle and the trailing vehicle, are presented in detail. A second experiment consists of a detailed investigation of aerodynamic forces on a two-vehicle platoon in back-to-back geometry. Following previous observations, the present experiment investigates a two-fold increase in drag force occurring at specific separations between the two vehicles. Color maps for the drag, side force and yawing moment coefficient ratios document the presence of a hysteresis loop-the drag on the leading vehicle as separation increases is different from drag as separation narrows. It is argued that the resonance with hysteresis represents a matching between the wavelength of turbulent flow structure and the spacing itself. A dimensional analysis relates the drag increase phenomenon to longitudinal separations between different types of vehicles.

Definition and Measurement of Transportation System Performance

Abstract: Performance measures are needed to inform decisions regarding the overall level of resources to devote to transportation, where to allocate these resources, and how best to use them. The first two types of decision require regular monitoring of the system to reveal problems, which present opportunities for improvement. A few, easily measured indicators of the major benefits and costs of the system are appropriate for this task. For the third type of decision, how to best address a specific problem, a more comprehensive set of benefits and costs must be considered. Indicators must be found for those benefits and costs that would be impacted by alternative means of addressing the problem, so that the overall impacts of the alternatives can be compared. This report discusses the benefits and costs of transportation and recommends specific measures to use as indicators of the benefits and costs, as well as data sources and methods of measurement. It discusses the role of intelligent transportation systems as both an object of measurement and a means of measurement

Why ITS Projects Should be Small, Local and Private: Lessons from Studies of Technological Change for the Deployment of Intelligent Transportation Systems

Abstract: In this paper, the author contends that in order to produce and capture useful knowledge, early Intelligent Transportation Systems (ITS) projects should be local, small, and focused on realistic goals. The importance of cooperative networks that support knowledge acquisition and diffusion is stressed. Additionally, the author promotes the usage of private industry, especially to perform tasks for which they are best qualified.

Intelligent Diagnosis Based On Validated And Fused Data For Relilability And Safety Enhancement Of Automated Vehicles In An IVHS

Abstract: Vehicles in an IVHS system rely heavily on information obtained from sensors. So far, most control systems make the implicit assumption that sensor information is always correct. However, in reality, sensor information is always corrupted to some degree by noise which varies with operating conditions, environmental conditions, and other factors. In addition, sensors can fail due to a variety of reasons. To overcome these shortcomings, sensor validation is needed to assess the integrity of the sensor information and adjust or correct as appropriate. In the presence of redundant information, sensor data must be fused, accommodating the findings from the validation process. In this report, we address the above issues. Key words: sensor validation, sensor fusion, data fusion, supervisory control, management of uncertainty, reliability, safety, Bayes networks, fault detection, Diagnosis, Influence Diagrams, risk analysis, decision making

The ISTEA/ITS Connection In California: The State Of The Relationship And Opportunities For Productive And Beneficial Linkages

Abstract: This report describes research which had three objectives: 1) investigate the current state of California's implementation of the Intermodal Surface Transportation Efficiency Act (ISTEA) with respect to Intelligent Transportation Systems (ITS), 2) assess the extent to which ITS has been integrated within the State's transportation planning process, and 3) recommend opportunities for linkages between ISTEA and ITS that have not yet been recognized. A literature search was first conduced which studied the key features of ISTEA, specific ITS-related issues, the institutional environment, and the specifics of ISTEA implementation in California. Secondly, a survey was conducted of transportation professionals who have knowledge and experience in performing field work implementing ISTEA.

The influence of close-following upon the cooling module air flow

Abstract: The purpose of this report is to experimentally determine the air flow through the cooling module (air-conditioning condenser plus engine radiator) of a Ford Windstar minivan when the van is operated at a fraction of a vehicle length behind a lead van. Pressures and temperatures are measured across the cooling module while the vans are in operation, and a standard calibration relates the pressure drop to the flow velocity through the cooling module. The Windstars are connected in tandem and driven on a test track at spacings of 0.22, 0.28, 0.38, 0.62, 0.88, and 1.0, expressed as fractions of the Windstar length. For the purposes of the test, an override switch is installed to allow the close-following van to be operated either with both cooling fans remaining on or with both fans disabled. Air flow is expressed either as a volume flow, in cubic meters per second, or as the fraction of the flow for a van operating in isolation at the same forward speed. With both fans disabled, the air flow is approximately twenty per cent of the isolation value at the shortest spacing, and increases to about sixty per cent at a spacing of one vehicle length. With both fans operating, the air flow is approximately fifty per cent of the isolation value at the shortest separation, and increases to about seventy per cent at one vehicle length separation. These represent substantial decreases in air flow, and will result in a diminished operating envelope for the vehicle in close-following.

Testing A Proposed Decision-oriented Framework To Understand Its Deployment Issues: An Examination Of The Travinfo Atis Project

Abstract: Deployment is at the forefront of current activity in California in the field of intelligent transportation systems. It is important to understand the multitude of issues associated with such deployment to increase the likelihood of a successful deployment initiative. A review and synthesis of the literature on deployment issues have been performed. This served as a basis for development of a proposed decision-oriented framework that may be used to recognize and organize issues for the deployment of intelligent transportation systems. The applicability of this framework to intelligent transportation systems is examined and tested. The test focuses on the specific case of the TravInfo Advanced Traveler Information System deployment based in the San Francisco Bay Area. TravInfo was a Field Operational Test sponsored by the Federal Highway Administration and was organized as a public/private partnership to capitalize on the different talents of both the public and private sectors. TravInfo was initially conceived in 1992, funded by the Federal Highway Administration's Field Operational Test program in 1993, began operation in September 1996 and recently completed its Field Operational Test phase in September 1998. The objective of the TravInfo FOT was to collect, integrate and broadly disseminate timely and accurate multimodal traveler information through a range of products and services, with different prices and capabilities, to meet consumer needs. TravInfo has an open- access database and architecture that allows the private sector participants to retrieve the data free of charge and re-package it for its ultimate dissemination to travelers via their commercial products and services. After the Field Operational Test concluded, the scope or magnitude of TravInfo entered a transitional phase and continues as-is relative to operations, administration, and management. During this phase it focuses on achieving additional objectives in the areas of expanding data coverage, upgrading data processing, marketing, management and administration. Key Words: Intelligent Transportation Systems, Advanced Traveler Information Systems, deployment, decision-oriented framework, TravInfo

Design of a Machine Vision-Based, Vehicle Actuated Traffic Signal Controller

Abstract: This project presents a signal controller algorithm to capitalize on the extended information provided by wide-area detection at isolated intersections. Using computer simulation, different control strategies are evaluated and the performance of the proposed wide-area detection system with conventional signal controllers is compared. The results indicate that wide-area vehicle actuated (VA) control can yield significant improvements over conventional VA control strategies.

Evaluation and Analysis of Automated Highway System Concepts and Architectures

Abstract: Author(s): Ioannou, Petros | Abstract: This is the final report for the project entitled \Evaluation and Analysis of Automated Highway System Concepts and Architectures" in response to the contractual requirements of the Memorandum of Understanding MOU# 235, between the Partners of Advanced Transit and Highways (PATH) and the University of Southern California, administered at the University of Califor- nia at Berkeley The purpose of this project was to select, evaluate and analyze a num- ber of promising Automated Highway System (AHS) operational concepts based on previous work The evaluation and analysis includes headway dis- tributions for vehicle following and lane changing, capacity calculations and the modeling, analysis and control of the resulting traffic flow The design, analysis and simulation parts of the project were performed at the Center of Advanced Transportation Technologies at the University of Southern Cali- fornia The work performed under this project is presented in the form of five reports presented in part I, II, III, IV, and V of this final report In addition to these reports oppy disks containing the \Inter Vehicle Spacing Software Tool" is included Keywords: Automated Highway Systems, Vehicle Following, Vehicle Spac- ing, Highway Capacity, Highway Safety, Accident Avoidance, Collision Avoid- ance, Braking Scenarios, Brake Performance, Lane Changing, Merging, Macro- scopic Models, Tra c Flow, Hybrid Systems, Roadway Controller

Implementation Of The Regulation Layer Using Shift

Abstract: In this report, the implementation in the SHIFT programming language of regulation layer control laws for the hierarchical California PATH Automated Highway System (AHS) is presented. The implemented regulation layer control laws are derived after the safe-feedback based maneuvers designed in previous PATH projects. These maneuvers were modified to use the acceleration of vehicles as the control signal. Simulation results and a summary of the code developed are included.

Design Of Fault Tolerant Control Systems For Ahs

Abstract: This report describes research in the area of fault detection and handling designs used in the longitudinal control system of platooned automated vehicles. Results are presented on experimental testing of the designs. The authors also describe a consistent interface between the fault detection and handling modules and how it was implemented in the SHIFT programming language for the specification of hybrid systems. In addition, the report describes part of the modeling formalism required for the formal verification of safety claims.

Data Utilization At California Transportation Management Centers

Abstract: This study looked at the operations and functions performed at the Caltrans Transportation Management Centers (TMC) with focus on the data sources, data processing, and performance measures. Recommendations are made for making greater use of archived real-time archived data. These include establishing a performance monitoring system, using the data to estimate performance measures, and providing procedures for data processing and dissemination.

Models of Vehicular Collision: Development and Simulation with Emphasis on Safety III: Computer Code, Programmer's Guide and User Manual for MEDUSA

Abstract: This report presents a user's manual and a programmer's guide for the computer program MEDUSA. The program is capable of simulating the impacts of several vehicles. It assumes that the collision are elastic, and is consequently applicable for low relative velocity impacts. A theoretical background of the collision detection algorithm is first given, followed by user's manual and programmer's guide.

Adaptive Baud Protocol For Wireless Communication

Abstract: In this paper, the authors propose an algorithm that increases and decreases the transmission speed according to a user-specified function. The design objective is to regulate baud as efficiently as possible and ensure that in each transmission interval, transmitter and receiver bauds are equal for some period of time during data transmission. An equivalent discrete-time version of the protocol is verified by using the COSPAN software. Application for this adaptive baud protocol for wireless communication is seen in a platoon setting within an Automated Highway System (AHS).

Field Test of Vehicle-Mounted, Forward Looking Range Sensor in Closed-Loop AVCS

Abstract: The purpose of MOU-233 is to evaluate and test a low cost, short range radar sensor developed by Amerigon corporation through a subcontract with the University of Southern California. The radar is designed to be used as a ranging sensor for automatic vehicle following applications. It is intended to be mounted in the front of the vehicle and provide measurements of the distance between the front of the vehicle and the rear of any vehicle or object ahead within a maximum distance of 17 feet. The output of the radar as supplied by Amerigon, is a 32-bit binary code, using one bit to represent each one of the range gates. In each sample, a bit value of '1' represents a range gate that detected a target and a value of '0' represents a range gate that has not detected a target. An algorithm has been developed to convert the binary code into distance measurements and to filter out undesirable effects such as noise, loss of target and other disturbances. Two prototype radar units have been delivered to PATH by Amerigon and we used them on the PATH vehicles for testing and evaluation. In this report we present the results of the testing and the evaluation of the Amerigon radar.

ITS Information and Services to Enhance the Mobility of Disabled Travelers

Abstract: This study examined the potential of advanced information systems to increase the mobility of disabled travelers using public transportation. A stated preference survey inquired as to whether subjects would make more trips by transit, paratransit, and/or real-time paratransit if kiosk, on-board, in-home, and/or personal information systems were available. The results show that these systems do have the potential to increase the use of public transportation by disabled travelers, as they allow for more trip flexibility that what is currently available. Regression and log-linear models show that transit users and those without cars are more likely to use transit if advanced systems were available. Wheelchair users are less likely than non-wheelchair users to use transit with advanced systems. KEY WORDS transit, paratransit, real-time paratransit, disabled travelers, ITS, transit information systems, mobility

Functional and Interface Requirements for Advanced Public Transportation Systems

Abstract: This report studies the current development of functional requirements and interface standards for the public transit industry It begins with a critical review of recent architecture efforts and their functional and interface requirements It then describes the results of a survey of public transit vendors that was conducted to learn about the technical characteristics of products and vendor attitudes toward interface standards Four case studies of recent technology applications in the San Francisco Bay Area are then described These case studies reflect that factors such as market timing, vendor-agency communication, and experience are key factors that affect the development of interface requirements and standards for the transit industry