Recent its_path_papers items

Connected Corridors: I-210 Aimsun Microsimulation Model

Thu, 17 Apr 2025 00:00:00 +0000

This document provides a description of the Aimsun Next model that was developed for the I-210 Pilot Integrated Corridor Management (ICM) System.

BTS (Version 1 .1) - Bottleneck Traffic Simulator User’s Manual

Mon, 18 Mar 2024 00:00:00 +0000

BTS can be used to evaluate a variety of changes in highway design to improve bottlenecks, such as: (1) addition of highway lanes, (2) addition of automated or HOV lanes, or (3) incident management strategies to reduce the frequency, duration and magnitude of incidents. BTS can also be used to project future highway conditions as baselevel traffic grows or driver behavior changes.

The new version of BTS was enhanced to include incident dependencies, variable weather conditions, reneging, and randomly varying traffic volumes. As of yet, BTS is not capable of analyzing highway performance on a network basis. However, even in large networks delays are often dominated by a few key bottlenecks. BTS can be used to study the performance of these key locations.

Design, Fabrication and Calibration of a Vehicle Tow Bar for Platoon Drag Measurements: A Working Report

Mon, 18 Mar 2024 00:00:00 +0000

A longitudinal stability model for a 2 vehicle platoon yields a pair of linearly coupled equations that model the dynamics of the tow bar and the vehicles. Using reasonable approximations, the vehicle separation distance obeys a second order non-linear differential equation with constant coeficients. Spring force and damping are provided by a special shock absorber link. The towbar linkage can be made to serve as a low pass mechanical system. The design spring constant of 60 1bfAn and a damping rate of 200 lbf/ft/sec yield a low-pass system with sufficient damping and a cut of frequency of 0.78 Hz. Steady state spring extensions are of the order of several inches for vehicle spacing from 0.2 to 1.0 vehicle lengths (200.24 inches).

A Focus Group Study of Automated Highway Systems and Related Technologies

Mon, 18 Mar 2024 00:00:00 +0000

The paper presents the findings of a focus group study of the automated highway system and its related technologies, specifically adaptive cruise control and collision avoidance systems, in the San Francisco Bay Area. A majority of the participants had a favorable reaction to AHS despite the fact that almost all were concerned about its safety and funding capability. Responses to the adaptive cruise control were generally positive. The focus group participants recognized the safety benefits, the convenience, and especially the stress reduction of using the automated highway system, when comparing it to the collision avoidance system.

Transportation Opportunities and Constraints: The Performance of Urban Highway Transportation

Mon, 18 Mar 2024 00:00:00 +0000

This report is the first in a series. The objective of the series is the definition of opportunities for shafp improvements in highway system performance, say, improvements on the order of two or more. Toward that objective, this first report considers system performance as such and the status of the economic and social services enabled by the system.

The report presents a first-pass analysis. Revisions are intended as the work continues.

Communication Requirements and Network Design for IVHS

Mon, 18 Mar 2024 00:00:00 +0000

This paper presents the communication needs between vehicles and the roadside infrastructure for IVHS applications. The requirements of each application, in terms of message length, frequency, and acceptable delay, are estimated. Based on these estimates, we assess the amount of radio spectrum needed to support these applications. We find that about 1.2 MHz is required to support full highway coverage. We discuss the topology and capacity allocation problems for the road-based network and present one possible implementation. We show a case study of network design and link capacity calculation for the San Francisco Bay Area highway system, as an illustration of the proposed solution. The results provide an indication for the communication media suitable for the network.

Traffic Management Systems Performance Measurement: Working Paper #2

Mon, 18 Mar 2024 00:00:00 +0000

Traffic Data System Improvement Plans were prepared for Caltrans Districts 1 1 (San Diego) and 12 (Orange County) as part of a research project on performance measurement for traffic management systems. The plans document data system objectives, data requirements, and existing data collection and management systems; evaluate the adequacy of existing systems; identify improvements and resource requirements; and document the districts’ priorities for action. Both districts have similar data systems, although Orange County’s is better developed. Both systems rely heavily on single-loop detectors for traffic surveillance. Both either have or plan to have current- generation data display and management software, complete coverage of urban freeways by loop-detector systems, extensive video surveillance systems, and fiber-optic communication systems. In addition, both provide or will provide computerized incident and equipment-status logging, adequate accident and traffic volume data...

A Link-Based Variational Inequality Model for Dynamic Departure Time/Route Choice

Mon, 18 Mar 2024 00:00:00 +0000

The dynamic user-optimal (DUO) departure time and route choice problem is to determine travelers’ best departure times and route choices at each instant of time. In a previous paper, we presented a route-based two-level optimal control model for the DUO departure time/route choice problem. However, this model is not appropriate for large scale transportation networks because some degree of route enumeration is necessary to solve the model. In this paper, we present a link-based variational inequality (VI) formulation for the DUO departure time/route choice problem so that route enumeration can be avoided in both the formulation and the solution procedure. The model extends our previous VI model for the DUO route choice problem to the case where both departure time and route over a general road network must be chosen simultaneously. By proving the necessity and sufficiency of this VI, we establish the equivalence of the VI formulation and the link-based DUO departure time/route...

An Object-oriented Database for IVHS

Mon, 18 Mar 2024 00:00:00 +0000

The objective of this proposal was to develop a database that integrates various elements-traffic simulation packages, data sets, and computational tools. The difficulty in integration was felt to be the incompatibility of data structures, formats, and software.

It was proposed to design, build and test a software environment with an open architecture that would facilitate a synergistic use of these software elements. The core of this environment was to be an object-oriented commercial database system that would be sufficiently general to support many software elements, and which would guide new software development.

The deliverables of this project were:

- A specification of an object hierarchy implemented in C++, and a graphical user interface to facilitate object specification;

- An interface to SmartPath so that simulation configurations and simulation runs can be stored in the database;

- An interface to the 1-880 database, developed...

A Method for Relating Type of Crash to Traffic Flow Characteristics on Urban Freeways

Mon, 18 Mar 2024 00:00:00 +0000

A method is developed to determine how crash characteristics are related to traffic flow conditions at the time of occurrence. Crashes are described in terms of the type and location of the collision, the number of vehicles involved, movements of these vehicles prior to collision, and severity. Traffic flow is characterized by central tendencies and variations of traffic flow and flow/occupancy for three different lanes at the time and place of the crash. The method involves nonlinear canonical correlation applied together with cluster analyses to identify traffic flow regimes with distinctly different crash taxonomies. A case study using data for more than 1,000 crashes in Southern California identified twenty-one traffic flow regimes for three different ambient conditions: dry roads during daylight (eight regimes), dry roads at night (six regimes), and wet conditions (seven regimes). Each of these regimes has a unique profile in terms of the type of crashes that are most likely...

Users’ Guide and Design Description SmartPath Simulator - Version MOU62

Thu, 14 Mar 2024 00:00:00 +0000

This document contains the user instructions and software design description for Version MOU62 of the SmartPath Simulator. The baseline version of the simulator including user instructions is described in [l].

A Time Headway Autonomous Intelligent Cruise Controller: Design and Simulation

Thu, 14 Mar 2024 00:00:00 +0000

Autonomous Intelligent Cruise Control (AICC) design is an important part of Advanced Vehicle Control Systems (AVCS). In this report, we design an AICC scheme for vehicle following with constant time headway spacing. The scheme maintains a steadystate inter-vehicle spacing decided by a desired time headway set by the driver. The longitudinal model of the Lincoln Town Car is used for simulations and testing. The vehicle is assumed to be equipped with a relative distance and speed measuring sensor,as well as an absolute speed measuring device.

Automated Highway Systems Operating Strategies and Events: A Driver’s Perspective

Thu, 14 Mar 2024 00:00:00 +0000

To ensure the identification of all major human factors issues, we have identified major options for operating fully automated AHS. These options are categorized in the following four dimensions: separation of traffic, transitions between manual and automated driving, normal automated driving and emergency response. Attributes critical to AHS human factors include (i) possible isolation of automated traffic from the manual traffic, (ii) possible separations among automated traffic by lane barriers, and (iii) the vehicle-following rule. We propose six scenarios featuring variations in these attributes. To...

Supply Side Evaluation of Radio Traffic Information

Thu, 14 Mar 2024 00:00:00 +0000

The study investigated data collection and dissemination processes of radio traffic information in the San Francisco Bay Area. Program directors from thirty two radio stations were interviewed to understand the processes and radio traffic reports were analyzed to evaluate the contents. The study showed that morning traffic conditions were broadcast most frequently. During morning peak hours from 6AM-9AM, the majority of the stations broadcast traffic conditions every 15 minutes. The content of the radio information is limited to traffic flow, incident conditions and transit schedule. The traffic conditions were reported in qualitative terms, information about travel time delays or lane blockage duration’s were not included in typical radio reports.

Notes From a Talk on Standards and IVHS Safety

Wed, 13 Mar 2024 00:00:00 +0000

This paper records a personal understanding of some features of the needs for standards and codes of practice in IVHS, and of the present position regarding them, in so far as the author has:

a. perceived them to be relevant to his own studies in the AVCS field in the U.S., mainly in relation to full automation.

b. been able to obtain access to the appropriate documents; he does not have easy access to a library containing defense standards.

Advanced Simulation Tools for Freeway Corridor Management

Wed, 13 Mar 2024 00:00:00 +0000

As part of the California PATH program, the Paramics microscopic traffic simulation model was applied to the I-580 freeway-arterial corridor. The main purposes of the project were two-fold:

- Develop the expertise and transfer the knowledge required in calibrating a large-scale freeway corridor with Paramics;

- Prepare a calibrated model for the I-580 corridor that could be used to address operational questions, evaluate potential improvement alternatives and provide input to the decision-making process.

In agreement with Caltrans District 4 and Headquarters, the study focused on the eastbound direction of I-580 (a 25 mile section) during the afternoon peak period of a typical weekday. The freeway network to be simulated included, in addition to the eastbound direction of 580, the westbound direction as well as a segment of I-680 and the portion of SR 84 connecting 580 and 680. The grid network also included a large number of surface streets and a total of...

Summary of Observations on July 1993 Study Tour to Japan

Tue, 12 Mar 2024 00:00:00 +0000

The purpose of this report is to document some lessons learned during the July 3-16, 1993 tour of Japan and Intelligent Vehicles ’93 Symposium attendance by PATH Director Donald E. Orne and Deputy Director/AVCS Program Manager Steven E. Shladover.

The tour was arranged by PATH through Japanese contacts to coincide with the Intelligent Vehicles ’93 conference. Most of the contacts were known to PATH either from introductions at various conferences or by visits to PATH offices.

Special attention was given by Orne and Shladover to consider the extent to which interaction with government, academic and industrial officials overseas serves both Caltrans and University program purposes. The conclusion is affirmative that program purposes are served.

Simulation of IVHS on the Santa Monica Freeway Corridor Using the INTEGRATION Model. Phase 2: Preliminary ATIS and ATMS Experiments

Tue, 12 Mar 2024 00:00:00 +0000

The general objective of the project is to investigate and quantify the likely benefits of implementing various ATMS and ATlS control strategies on the real-life Santa Monica freeway corridor in Los Angeles.

The different strategies to be tested in Phase 2 include freeway ramp metering, real-time traffic signal optimization, route guidance systems, and combinations of these strategies. Investigations of different strategies are performed for the same network conditions (portion of the Santa Monica freeway corridor previously coded in Phase 1) and under the same demand level (typical morning peak period). Effects of incidents are to be analyzed.

Primary focus at this stage of the study was more on developing and testing the methodologies for modelling various IVHS strategies than on the quantitative simulation results.

The Role of Teamwork in a Planning Methodology for Intelligent Transportation Systems: Volume 1

Tue, 12 Mar 2024 00:00:00 +0000

In this research we propose a framework for a transportation planning methodology that recognizes the key role that teamwork plays in the decision-making process. We recognize that the transportation planning process has evolved for many reasons, and develop a cohesive framework for providing intelligent decision support to teams deliberating planning problems. The design methodology considers both user and functional issues in building a matrix of building block functions (BBFs) to support a particular planning process. We illustrate the design methodology by using as an example a recent planning problem from California.

Measuring the Aggregate Productivity Benefits from ITS Applications: The California Experience

Tue, 12 Mar 2024 00:00:00 +0000

This research provides the first evidence of whether and how ITS contributes to economic growth and productivity – an objective established by the California Transportation Plan and ITS in particular. The next set of questions includes, what industries are most affected by ITS applications? Does it matter how many ITS applications are present, in other words, are there diminishing returns to similar ITS projects? Finally, does it matter how ITS projects are combined? This latter question also arose out of our research on production functions as well, and will be a central part of the subsequent research agenda.

Advances in Fuzzy Logic Control for Lateral Vehicle Guidance

Tue, 12 Mar 2024 00:00:00 +0000

A candidate for intelligent control for lateral guidance of a vehicle is a fuzzy logic controller (FLC). The details of the most recent FLC with a rule base derived from heuristics and designer insight to the problem at hand, as well as a method for estimating a projected lateral displacement are presented along with simulation results. The structure of this FLC is suited to incorporate human knowledge about the steering operation by its choice of inputs and outputs of the FLC which are natural to human steering operation. In addition, a method that makes use of preview information regarding upcoming road curvature is developed and simulated based on human steering operation. This method projects an estimate of the lateral error relative to the reference track at a specified look - ahead time. Simulations imply that there exists an optimal look - ahead time. Too short a time does not make full use of the preview information, while too long a time results in inaccurate estimates...

A Comparison of Traffic Models: Part II Results

Tue, 12 Mar 2024 00:00:00 +0000

This working paper is the second part of a series comparing dynamic traffic flow models. It documents the results of comparison based on the framework defined in Part 1. The traffic models selected for comparison are DINOSAUR, DYNASMART, INTEGRATION, and METS. The areas of comparison comprise four categories: functionality, traffic dynamics, route choice mechanism, and network performance.The first category was compared with a checklist of functions. A total of thirteen test scenarios were constructed to compare models for the last three categories.

Effect of Longitudinal Control on Capacity

Tue, 12 Mar 2024 00:00:00 +0000

This paper focuses on what benefits a longitudinal control system can be expected to render to the present highway system.There are three major reasons why longitudinal control should be expected to improve traffic flow and to reduce accidents.

(1) It may permit higher traffic densities with uniform spacing forming an even distribution with increased travel speeds and consequently higher capacity.

(2) It may reduce the rate of rear-end collisions that occur on urban freeways.

(3) It can provide increased stability in traffic flow (shockwaves due to human response characteristics are the main cause in limiting traffic capacity on today's freeways.)

Incident Management with Advanced Traveller Information Systems

Tue, 12 Mar 2024 00:00:00 +0000

Advanced Traveller Information Systems (ATIS) can be used to collect and disseminate dynamic information about travel times on highway links. One of the potential uses of these systems is to manage incidents. The objective of this research is to showunder what incident conditions is it relevant to provide real time traffic information to travellers.

A model that uses graphical queueing techniques is utilized to define cases when ATIS is beneficial and cases when it is not, and to evaluate its benefits as measured by travel time savings. The model is applied to a simple road network with two parallel bottlenecks. We analyze an off-peak incident scenario where a user optimal strategy is implemented to disseminate information only to vehicles equipped with ATIS. The different cases of queue evolution that can result are described, benefits to guided and unguided travellers and the sensitivity of benefits to relevant parameters are also analyzed.

It is found that once...

Highway Electrification: An Exploration of Energy Supply Implications

Tue, 12 Mar 2024 00:00:00 +0000

The objective of this preliminary report is to explore the energy supply opportunities and implications of electrifying highways. An important assumption in this report is that the technology and general cost structure for generating and storing electricity does not change significantly in the future. In other words, we ignore the possible use of super conductive materials to store electricity during off-peak times, which, if feasible, would greatly reduce average electricity costs. A future report will examine the opportunities and implications of breakthroughs in superconductivity.

The report is organized as follows. First, the relationship between transportation and electricity demand patterns are investigated. These relationships are then explored for different regions of the country. With this background, we then identify the implications of electrifying highway transportation for the electricity industry, including an analysis of energy supply considerations.

Major Failure Events of Automated Highway Systems: Three Scenarios from the Driver’s Perspective

Tue, 12 Mar 2024 00:00:00 +0000

Automated Highway Systems (AHS) have the potential for offering large capacity and safety gains without requiring significant amounts of additional right-of-way. Since the general public will be the users of the AHS, human factors must play a pivotal role in the research and development of AVCS technologies and AHS operation. In two companion reports, three attributes critical to AHS human factors were identified and seven scenarios featuring variations in these attributes proposed. To ensure the identification of all major compounding attribute combinations, detailed operational events, from the perspective of the driver, were identified. This paper focuses on failure events, where a failure event is defined to be the occurrence of a functional failure during a normal operational event.

After briefly reviewing the seven "first-generation'' scenarios, this report first describes the criteria for selecting the three "second-generation'' scenarios and then reports the selection...

Robust Computation of Optical Flow in a Multi-Scale Differential Framework

Tue, 12 Mar 2024 00:00:00 +0000

We have developed a new algorithm for computing optical flow in a differential framework. The image sequence is first convolved with a set of linear, separable spatiotemporal filters similar to those that have been used in other early vision problems such as texture and stereopsis. Our analysis of the measurement errors leads us to develop an algorithm based on a robust version of total least squares. Each optical flow vector computed has an associated reliability measure which can be used in subsequent processing. The performance of the algorithm on the data set used by Barron et al. (CVPR 1992) compares favorably with other techniques. In addition to being separable, the filters used are also causal, incorporating only past time frames. The algorithm is fully parallel and has been implemented on a multiple processor machine.

By being fully parallel, the algorithm can be performed by an array of processors in real time. In addition, the differential method is computationally...

The Los Angeles Freeway Service Patrol (FSP) Evaluation: Site Selection and Database Development

Tue, 12 Mar 2024 00:00:00 +0000

The Los Angeles Freeway Service Patrol (FSP) Evaluation project is measuring the effectiveness of the FSP program on a specific freeway site in Los Angeles. This report describes the site selection and database development phases of the project. From an initial list of ten possible sites, detailed analysis was performed in order to rank the sites according to specific parameters developed by the study team. Site selection was based on congestion levels, average travel speeds, shoulder width, number of in-lane FSP assists, average daily traffic, directionality and the density of functional loop detectors. The site selected was FSP Beat 8, which is located on Interstate Route 10, between Eastern Avenue and Santa Anita Avenue.

Once the site was selected, a detailed, comprehensive, computerized database was developed. This database completely describes the traffic conditions along Beat 8 for 32 weekdays, for a total of six hours each day. This 192-hour database includes detailed...

Time Benefits of New Transportation Technologies: The Case of Highway Automation

Tue, 12 Mar 2024 00:00:00 +0000

This paper examines the role of travel time in the choice of transportation technologies. First, the components of travel time are introduced and compared among alternative modes. Next, a series of highway automation concepts is created, and the time benefits of each are discussed. Finally, the effects of automation on highway performance are modeled and evaluated, first looking at the space efficiency of highways, then measuring the benefits of increased capacity and increased velocity.

The paper demonstrates that even simple forms of highway automation can provide important travel time benefits. Automated low-speed and stationary merging can reduce queueing at the entrances to bridges, tunnels and other bottlenecks. And “mini-highways” can reduce delays crossing urbanized areas.

Highway automation may achieve great benefits within a few niche markets. Butthese markets are likely in congested existing cities -- where construction of new conventional highways is...

Integrated Traffic and Communications Modeling Environment for ATMIS

Tue, 12 Mar 2024 00:00:00 +0000

The aims of this MOU were to create an integrated environment for modeling traffic flow, sensor data, and the communications infrastructure for ATMIS. The research plan was to build separate tools for measuring the communications requirements of ATMIS traffic, modeling a mobile radio communications environment, and communications network design, and then to integrate them in an object-oriented environment from which one could also access existing or new road traffic simulation packages.

Section 1 of the report presents a framework for estimating the vehicle-roadside communications requirements taking the San Francisco East Bay region as a case study and for determining whether existing wide-area wireless technologies can be used to support those requirements. The study should be viewed within the contexts provided by the National ITS Architecture and the California ITS System Architecture as presented in Caltrans’ Advanced Transportation Systems Program Plan. When completed,...

Driving Intelligence Replacement in a Decision-Oriented Deployment Framework for Driving Automation

Tue, 12 Mar 2024 00:00:00 +0000

What some human drivers have done wrong has been blamed for much of the problem associated with the current highway systems. For example, driver inattention, fatigue and other human errors have often been cited as major sources of safety hazard on current highways and human capabilities as major limitations on current highway capacity. Such human deficiencies and the pervasive urban traffic congestion have motivated the concept of Automated Highway Systems (AHS). The fundamental objective of AHS is to achieve user and societal benefits through replacing human driving by automated machine driving. The first fundamental thesis of this paper is that safe replacement of human driving on highways by automation requires a rigorous examination into what most human drivers have been doing right on the current highway systems. Such an examination would provide much insight into the functional requirements for AHS, i.e., what machines must do to emulate or improve human driving. Furthermore,...

The Spatial Evolution of Queues During the Morning Commute in a Single Corridor

Tue, 12 Mar 2024 00:00:00 +0000

This paper presents a qualitative description of the evolution of traffic congestion during the morning rush hour in a long freeway leading to a single destination. Traffic is generated at the freeway’s many on - ramps during a short period of time and then is assumed to subside. Capacity limitations create queues on the ramps and the freeway, which is assumed to evolve according with the hydrodynamic theory of traffic flow. A special case that can be described with just a few parameters is analyzed in detail.

The simplicity of our scenario allows the results to be easily verified independently; they can then be used to check whether ‘the existing traffic assignment models are consistent with the basic laws of traffic flow. We found that unreasonable results are obtained with “point queue’’ models, currently a favored approach in the dynamic traffic assignment literature. A computer program, based on the cell transmission model (Daganzo, 1992), is put to the same test.

Summary of Selected, Significant ITS and ITS-related Policies and Programs in Europe and the US (with Japan Supplement)

Tue, 12 Mar 2024 00:00:00 +0000

This research project explored institutional and organizational factors contributing to successful deployment of Intelligent Transportation Systems (ITS). The researchers conducted a comprehensive internet/literature search on the status of ITS programs in Europe and the U.S., interviewed principals involved in ITS deployment both at the policy and project levels, and from the public and private sectors, and developed four case studies of successful ITS deployment. Results from the internet/literature search and responses from the survey/interviews were analyzed to identify critical institutional and organizational factors for successful deployment and operation of ITS systems/services. The methodology allowed for both a top-down (programs and policies) and bottom-up (project experiences) review and analysis.

Ultrasonic Ranging Control Board Documentation

Mon, 11 Mar 2024 00:00:00 +0000

This document specifies the theory of operation of version B of the PATH ultrasonic range control board for the IBM PC. Two modes are discussed in detail. The first is the ping mode, which uses a single transducer both to send an ultrasonic pulse and receive its echo. The second, called the phased-array mode, uses a single transducer to send the pulse and two other transducers to receive echoes and perform path-length matching in order to reduce the effects of multi-path echoes. Both the hardware and the software used to perform these functions are examined.

Transient Aerodynamics in Vehicle Interactions: Data Base Summary

Mon, 11 Mar 2024 00:00:00 +0000

The vehicles in a platoon will experience transient aerodynamic forces as vehicles leave and join the platoon at various locations. A platoon of scale vehicle models is placed in a wind tunnel and measurements are made of the transient forces and moments as one of the vehicles is moved into and out of the platoon. The results from the wind tunnel experiments will allow the computer vehicle control algorithms to better predict the transient aerodynamics the vehicles in the platoon will encounter during leaving and joining maneuvers.

Since a lane change (either leaving or joining a platoon) maneuver occurs on the same time scale as changes in the flow field, characterization of the transient forces and moments becomes of paramount importance. In these experiments, one vehicle is moved out of and into the platoon at six different accelerations to simulate lane changes at six different time scales, the longest (smallest acceleration) representing the static case and the shortest...

Decision Support Systems for Managing and Applying ITS Research

Mon, 11 Mar 2024 00:00:00 +0000

This study is presented in three related papers. The first develops a structure for making decisions regarding Caltrans/PATH research. It describes a research cycle in which real world needs and opportunities fed into a process by which research priorities are set, proposals invited, and projects are selected. These research projects ultimately provide information that can be used for further research or for implementation. Implementation changes society and technology and leads to new needs and opportunities, which in turn feed into the research process. The second paper develops and describes the process by which proposals are evaluated. The third paper describes how the products of research and implementation have been analyzed, summarized, and presented to researchers, potential implementers, and other decision makers via the Internet, thus supporting their decisions regarding further research and implementation and thereby moving research results into practice.

AHSCAP Dynamic Traffic Assignment Program User’s Manual and Design Description

Mon, 11 Mar 2024 00:00:00 +0000

This research seeks to provide an understanding of the capacity and throughput require- ments of an automated highway system(AHS) via development of a computer model that represents system capacity and demand, operational characteristics, and defined infras- tructure. To do that, a variety of scenarios representing traffic input to the system must be represented. Also, a variety of infrastructures representing different system configurations must be represented. This includes the locations of entrances and exits.

Detailed vehicle-based simulations have been used to investigate AHS capacity and throughput requirements in past studies(see [5]). In these studies, flows of 6000-8000 vehicles/lane/hour were achieved using the platoon organization of vehicles. However, disturbances to traffic flow due to lane changes were noted and also not all vehicles were able to reach their respective exits. This computer model addresses the issues of requiring all vehicles to reach their...

LANE-OPT Users Manual Version 1.0

Mon, 11 Mar 2024 00:00:00 +0000

This document is the user manual for LANE-OPT. LANE-OPT is a linear program based software package that optimally assigns traffic to lanes on an automated highway. The program is based on a workload model, such that each lane/segment has a fixed capacity than can be allocated among: (1) straight traffic, (2) lane changes into the lane, (3) lane changes out from the lane, and (4) lane changes that pass through the lane. Each of these four movements produces a user-specified workload. The computer program models the highway as a multi-commodity flow network, where commodities represent destinations. The linear program maximizes total network flow, accounting for lane/segment capacities and a fixed origin/destination pattern, which is expressed on a proportion basis.

Are the Objectives and Solutions of Dynamic User-Equilibrium Models Always Consistent?

Mon, 11 Mar 2024 00:00:00 +0000

Traffic assignment models are an important component in analyzing the relationship between demand and supply in the transportation network for design, planning, and control purposes. The static traffic assignment model has been used in practice for several decades. With the latest development in the area of Advanced Traffic Management Systems (ATMS) and Advanced Traveler Information Systems (ATIS), there is an increasing demand for dynamic traffic assignment models to serve as a basis for studying various issues in these areas.

Existing dynamic user-equilibrium traffic assignment (DUETA) models are mostly expanded from the static user-equilibrium traffic assignment model by intro- ducing the time dimension along with a group of additional constraints. Whereas the equivalency between the solution to the traffic assignment model and the user-equilibrium condition as defined by Wardrop is well established in the static case, the same may not be true for the dynamic case....

Beyond Tele-substitution: A Broader Empirical Look at Communication Impacts

Mon, 11 Mar 2024 00:00:00 +0000

Information on the number and types of communication activities (including travel) engaged in over a period of four consecutive days, at two points in time about six months apart, was collected from 91 respondents. A system of structural equations was developed and estimated, expressing the quantity of each type of communication at time 2 as a function of quantities of communication of each type at time 1, the elapsed time between measurements, and exogenous sociodemographic variables. All "own" lagged effects (that is, the effect of one communication type in wave 1 on the same type of communication in wave 2) were found to be positive and (except for information object delivery) highly significant. The "elapsed time" variable was always positive and (except for personal meetings and, in one model, information object delivery) significant; these effects indicate net generation of communication activities over time. Significant "cross" lagged effects (that is, the effect of one...

Optimized Lane Assignment on an Automated Highway

Mon, 11 Mar 2024 00:00:00 +0000

Highway automation entails the application of control, sensing and communication technologies to road vehicles, with the objective of improving highway performance. It has been envisioned that automation could increase highway capacity by a factor of three. To attain this capacity, it will be important to minimize the amount of lane-changing and optimally assign vehicles to lanes. This paper develops and applies a linear programming based lane assignment model. The highway system is modeled as a multi-commodity network, where the commodities represent trip destinations (i.e., exit ramps on highways). An unusual feature of the model is that capacities are defined by bundle constraints, which are functions of the flow entering, leaving, continuing and passing through lanes in each highway segment. The objective is to maximize total flow, subject to a fixed origiddestination pattern, expressed on a proportional basis. The model is tested for highways with up to 80 segments, 20 destinations...

A Research Plan for Highway Vehicle Navigation Technology

Mon, 11 Mar 2024 00:00:00 +0000

This working paper describes a proposed research plan to explore the application of advanced technology to highway vehicle navigation. The proposed research addresses navigation, communication, and control technology, benefits of improved vehicle navigation, system requirements, and design and implementation issues. The paper introduces the issues involvedin highway vehicle navigation and communication, and discusses recentdevelopments in vehicle navigation technology.

The importance of a vigorous program of research in this area is identified, and six near term and ten follow-on projects are described, including provision estimates of the level of effort required.

Using Technology to Improve Transportation Services

Mon, 11 Mar 2024 00:00:00 +0000

Today's transportation systems are well deployed in the developed nations, and they and their supporting activities are technologically and institutionally mature. This situation is exceptional in the perspective of the last 200 years of transportation development, during which new systems were innovated and wave after wave of construction undertaken.

An examination of the ways technologies were shaped and adopted in the past reveals that today's view of technology-based opportunities is also exceptional. Consistent with system maturity, the search for improvements is focused on marginal changes in service quality or decreases in costs. Electronics technology, for example, is being applied to smooth highway traffic, improve microwave aircraft landing systems, and tighten shippers logistics' systems. Such marginal improvements were, of course, sought in the past. The difference then was parallel interest in new system or subsystem designs. In the context of these designs,...

Transit ITS Simulator (TRANSITS): Design Document

Mon, 11 Mar 2024 00:00:00 +0000

This report describes a simulation model developed to evaluate the impact of using Intelligent Transportation Systems (ITS), such as Global Positioning Systems (GPS) for bus tracking, on controlling buses in wide-area transit networks. Control strategies with ITS will be compared against those without ITS (i.e., they do not rely on communication or tracking). The model is developed using a general-purpose simulation language, AweSim (Pritsker, 1997). The simulation model is generic and independent of any dedicated transit network. The model has high flexibility and can be used to simulate different kinds of transit networks with varying numbers of bus lines and different travel patterns. The user has the flexibility to input the appropriate control strategy at each bus stop. With this approach an identical replica of an actual system can be simulated. A set of experiments is being developed to analyze the use of ITS on several performance metrics, including average bus arrival...

Institutional Aspects of Bus Rapid Transit – A Macroscopic Examination

Mon, 11 Mar 2024 00:00:00 +0000

This report investigated the institutional aspects of Bus Rapid Transit through a macroscopic examination of relevant issues ascertained through a literature review, a series of project team brainstorming meetings, and input from members of the Federal Transit Administration’s Bus Rapid Transit staff. The literature review provided insight into the history of Bus Rapid Transit concepts ranging from very early research in the United States in the late 1950s, continuing with dual mode systems and early busways in the 1960s and 1970s, international experiences in Latin America and Canada, and the return of interest in and research on Bus Rapid Transit in the U.S. Several dozen issues were identified and were grouped into the following nine categories: intergovernmental and inter-organizational; intra-transit agency; political; public relations andmarketing; funding and finance; labor; safety and liability; planning and land use; and the physical environment. The issues that were...

Ideal Dynamic User-Optimal Route Choice: A Link-Based Variational Inequality Formulation

Mon, 11 Mar 2024 00:00:00 +0000

The ideal dynamic user-optimal (DUO) route choice problem is to determine vehicle flows on each link at each instant of time resulting from drivers using actual minimal-time routes. Actual route time is the travel time incurred while driving along the route. In a previous paper, we presented a route-based optimal control model for the ideal DUO route choice problem. However, this model is not appropriate for largescale transportation networks because some degree of route enumeration is necessary to solve the model. In this paper, we first present the traffic network constraints and link-based DUO route choice conditions. Then, we introduce a link-based variational inequality (VI) formulation for the ideal DUO route choice problem so that route enumeration can be avoided in both the formulation and the solution procedure. By proving the necessity and sufficiency of this VI, we demonstrate that the VI formulation is equivalent to the link-based DUO route choice conditions.

AHS Deployment: A Preliminary Assessment of Uncertainties

Fri, 8 Mar 2024 00:00:00 +0000

This paper provides a preliminary assessment of uncertainties, both technical and institutional, associated with the deployment of Automated Highway Systems (AHS). Seven issues are addressed, concerning whether: (1) People use AHS, ( 2 ) Auto makers manufacture equipped vehicles, (3) Government builds AHS roadways, (4)Highways can evolve, ( 5 ) Interest groups do not obstruct, (6) Performance is adequate, and (7) Technology is feasible. For each issue, a table is provided that lists some of the more critical uncertainties.

Towards a Technology Assessment of Highway Navigation and Route Guidance

Fri, 8 Mar 2024 00:00:00 +0000

This paper is intended as a first look at the required assessment of technology. It is preliminary in the sense that it attempts to identify the issues and to identify some aspects of technology assessment that are needed to deal with them. It's aim is to raise some of the fundamental questions that arise in connection with the evaluation of this technology, and to suggest some further work for dealing with them. A more extensive research plan for looking at the various aspects of automobile navigation is to be found in Gosling [1988].

TravInfo Evaluation Plan: Update 1

Fri, 8 Mar 2024 00:00:00 +0000

TravInfo is a public/private partnership formed to provide wide-spread dissemination of real-time information on transportation conditions and travel options. A fundamental premise is that a public surveillance and database system, designed to open-architecture standards, will be an effective stimulus for private sector innovations in ATIS (Advanced Traveler Information Systems) technologies and, ultimately, their deployment.

TravInfo is a Field Operational Test of a centralized database providing easy access to real-time travel information on all modes of transportation in the Bay Area. TravInfo will test the thesis that comprehensive and timely information on the Bay Area’s complex transportation system will result in reduced congestion and traffic delay.

Properties of Link Travel Time Functions Under Dynamic Loads

Fri, 8 Mar 2024 00:00:00 +0000

This note examines a general form of link travel time functions considered in the dynamic traffic assignment literature and shows that it only makes some physical sense in the special case where each function denotes either a link with no spatial dimension containing a point queue, or a link with constant travel time and no queueing. Roadway segments exhibiting both phenomena must be represented by two links in series.

User Perceived Benefits with Navigation Systems

Fri, 8 Mar 2024 00:00:00 +0000

It has often been assumed that travel time savings are only beneficial to the users of route guidance and navigation systems. In particular, absolute travel time savings have been emphasized, but there has been little interest in relative time savings between equipped and unequipped vehicles. Part 2 of this report investigates to what extent relative travel time savings decrease as the percentage of equipped vehicles increases.

In order to compensate for a possible decrease in relative time savings, some other potential services that can be provided by navigation systems are identified in Part 3. This report focuses on a particular category of users: commuters. Unfamiliar drivers can be helped by the navigation system in the task of planning and following a route. Hence, it is likely that these users perceive some significant benefits. However, commuters do not need these services and are therefore a more difficult group of users to satisfy. Some field results from the...

Daily Activity and Multimodal Travel Planner: Phase 1 Report

Fri, 8 Mar 2024 00:00:00 +0000

Travel constitutes an integral part of our daily life. Only by traveling are we able to engage in a variety of activities at different locations. Since the extension of our movement is restricted by the amount of time that is available and the speed with which we can move, it is important that our travel be efficiently organized such that the time resource can be best utilized to engage in activities in an efficient manner. One approach to achieving this is to choose less congested and faster routes. The use of in-vehicle advanced traveler information systems (ATIS) for this purpose has been extensively discussed in the ITS literature.

Little attention has been directed, on the other hand, to achieving the same goal by developing efficient travel itineraries. This becomes important when a traveler visits a number of places in a tour. Examples include a delivery truck driver who is supposed to deliver goods to multiple locations, or a tourist who wishes to visit a number...

Freeway Performance Measurement System: Final Report

Fri, 8 Mar 2024 00:00:00 +0000

PeMS is a freeway performance measurement system for all of California. It processes 2GB/day of 30-second loop detector data in real time to produce useful information. Managers at any time can have a uniform and comprehensive assessment of freeway performance. Traffic engineers can base their operational decisions on knowledge of the current state of the freeway network. Planners can determine whether congestion bottlenecks can be alleviated by improving operations or by minor capital improvements. Travelers can obtain the current shortest route and travel time estimates. Researchers can validate their theory and calibrate simulation models.

PeMS is a low-cost system. It uses the Caltrans network for data acquisition. It is easy to deploy and maintain. It takes under six weeks to bring a Caltrans district online. Functionality can be added incrementally. PeMS applications are accessed over the WorldWide Web. Custom applications can work directly with the PeMS database....

Safety and Efficiency Tradeoff Analysis for Automated Highway System: Part 3: Longitudinal Separation on AHS: A Trade-off Between Collision Probability/Severity and Capacity

Fri, 8 Mar 2024 00:00:00 +0000

This report develops a probabilistic model for analyzing longitudinal collision/safety between an abruptly decelerating vehicle and its immediate follower on an Automated Highway System. The input parameters are the distance between the two vehicles, their common speed prior to the failure, the reaction delay of the following vehicle and a bivariate distribution for the two deceleration rates. The output includes the probability of a collision and the probability distribution of the relative speed at collision time. These safety consequences can be used to balance the desire to increase AHS capacity with the safety requirements.

We use this model to compare the safety consequences associated with the platooning and "free-agent" longitudinal-separation rules. We also demonstrate that the free-agent rule implemented with a potential technology of fast and accurate emergency deceleration, under some reasonable conditions, can avoid collisions while offering a high freeway...

Modeling of the Brake Line Pressure to Tire Brake Force Subsystem

Fri, 8 Mar 2024 00:00:00 +0000

One of the most challenging problems in automated vehicle control is when and how to apply the brakes. In order to deal with such a problem, a good understanding of the dynamical behavior of the braking mechanism is essential. In this report we use experimental data from a series of tests performed in collaboration with Ford research engineers to modelthe brake line pressure to tire brake force subsystem. This model will be used together with that of the master cylinder to line pressure currently under study, for developing an overall model for the braking mechanism. The brake model will later be used for longitudinal control design and automatic vehicle following.

TMDD Standards Update Recommendations – Data Structures

Tue, 19 Sep 2023 00:00:00 +0000

This document provides a set of recommendations for modernization of the Traffic Management Data Dictionary (TMDD) (1), currently at version 3.1. These recommendations are based upon the following: Connected Corridors project experience; three previous technical memorandums provided under this project discussing the current and future state of transportation, the state of the supporting technology for information exchange, and a review of the TMDD standard; a gap analysis based on the three technical memorandums delivered as part of this project. The intention of this document is to inform the Institute of Transportation Engineers (ITE) committee responsible for TMDD, the California Department of Transportation (Caltrans), and users of the standard of potential improvements in the standard that should improve its ability to serve current and future transportation and traffic management needs

TMDD Standards Review Technical Memorandum

Tue, 19 Sep 2023 00:00:00 +0000

This document presents a review of the Traffic Management Data Dictionary (TMDD) standard, specifically version 3.03d with some analysis of the newest version 3.1, released in January 2020. The intention of this document is to provide a review of this standard for transmission of data between traffic management centers (TMCs), with specific commentary on usability of the standard with specific examples based on its implementation in the Caltrans I-210 Connected Corridors program. TMDD is published by the Institute of Transportation Engineers (ITE), an international organization of transportation engineers and the American Association of State Highway and Transportation Officials (AASHTO), an organization of highway and transportation officials in the United States with members from all 50 states, the District of Columbia, and Puerto Rico. The standard is provided in two parts, along with a reference guide, providing guidance for those developing, procuring, or implementing systems...

TMDD Standards Update Recommendations – Data and System Security

Tue, 19 Sep 2023 00:00:00 +0000

This document provides recommendations for modifications to the current TMDD standard. Its goal is to provide a foundation for modernizing the standard. This document specifically provides recommendations for implementing this project’s gap analysis recommendations related to providing security guidance for each approved transmission protocol. Included in this document are recommendations related to a new volume of the specification dealing with minimum security requirements and security recommendations for each data transmission protocol.

Modernization of Center-to-Center Data Communication Standards: Gap Analysis Technical Memorandum

Tue, 19 Sep 2023 00:00:00 +0000

This document provides a gap analysis based on three previous technical memorandums delivered as part of this project, including a review of the Traffic Management Data Dictionary (TMDD) standard, a review of current and future transportation needs, and a review of the state of the art in technology and systems development. The intention of this document is to provide a review of this standard for transmission of data between traffic management centers (TMCs), with explicit commentary on usability of the standard with specific examples based on its implementation in the Caltrans I-210 Connected Corridors program.

Current and Future Transportation Management High-Level Requirements Technical Memorandum

Tue, 19 Sep 2023 00:00:00 +0000

This document presents a review of the current and future requirements for information exchange between traffic management centers, with emphasis on the changes expected due to the changing nature of transportation and the advances in technology that are becoming prevalent in the transportation ecosystem. The intent of this document is to provide a look at the source of changes required within center-to-center communication and new requirements that will need to be addressed as transportation undergoes significant change due to new transportation modes, technology advances in connected and automated vehicles, advances in infrastructure elements, and other changes that are expected in the future.

Modernization of Center-to-Center Data Communication Standards: Sample Implementation Administration and User Guide

Tue, 19 Sep 2023 00:00:00 +0000

This document provides a guide to the reference sample application developed under the Traffic Management Data Dictionary (TMDD) modernization contract. The application provides a sample implementation of a SOAP implementation using the XML Schema Definition (XSD) and Web Service Description Language (WSDL) developed under the contract. In addition, it provides a sample implementation of a Kafka/JSON based messaging implementation. Both implementations utilize a sample set of data captured during the I-210 Connected Corridors contract. The application is intended for use by experienced Information Technology (IT) personnel as an example of both SOAP and Kafka implementations of a Center-to-Center (C2C) information exchange system.

Travlnfo Field Operational Test Evaluation: Target Study Final Results

Wed, 8 Feb 2023 00:00:00 +0000

This paper presents the final results of the Target Study conducted for the evaluation of the Travinfo Field Operational Test. Four waves of telephone surveys were conducted in 1997 and 1998 among commuters shortly after major incidents on a selected corridor. The case study corridor is a 16 mile segment of US 101 serving major cities between San Francisco and San Jose.The commuter surveys were aimed at an understanding of travel behavior when major incidents occur. The results of the surveys suggest that traveler behavior is not greatly affected by individual incidents causing delays of less than 15 minutes. Although a fair portion of commuters listen to radio traffic reports, they do not often modify their travel behavior in response. In general, commuters do not believe that changing their travel plans will result in shorter travel time. Commuters tend to believe that their normal travel plans are faster than or as fast as alternate plans; however, they value traffic information...

A Conceptual Approach for Developing and Analyzing Alternate Evolutionary Deployment Strategies for Intelligent Vehicle/Highway Systems

Wed, 8 Feb 2023 00:00:00 +0000

Intelligent Vehicle Highway Systems (IVHS) comprise a spectrum of technologies, with both short - term and long - term applications. Eventually, deployment of IVHS may lead to fully automated, hands-off and feet-off, driving. In the short - term, IVHS has included traffic control systems, in - vehicle information systems, and a range of new roadway sensors.

This paper develops a framework for planning the evolutionary deployment of IVHS technologies. It defines an evolutionary deployment sequence, identifies baseline assumptions, and presents strategies for achieving success. This paper also develops an evaluation framework, consisting of strategy development, strategy evaluation, technology and barrier identification and strategy refinement. Lastly, the paper presents examples of evolutionary deployment sequences, and discusses both the market and technological ramifications ofthese sequences.

Consumer Research on Advanced Traveler Information Systems: TravInfo Field Operational Test

Thu, 22 Dec 2022 00:00:00 +0000

The paper describes the evaluation framework of the TravInfo project, a field operational test of the San Francisco Bay Area advanced traveler information system. The purpose of the evaluation study is to measure changes in individual travel patterns that result from the TravInfo project and to assess traveler acceptance of and preference for advanced traveler information technology. The anticipated effects of TravInfo on Bay Area travelers were described using some of the economic concepts of supply and demand relationships between information providers and information users. Consumer choice concepts were investigated to better understand the impact of ATIS on travel choices with real-time traveler information and to establish a conceptual framework in which the TravInfo evaluation study could be conducted. In the case of the TravInfo field operational test, the short-term impact of advanced traveler information systems on travel behavior would be difficult to measure because...

Evaluating the Impact of ITS on Personalized Public Transit

Thu, 22 Dec 2022 00:00:00 +0000

The focus of this project is to study alternative system architectures and ITS technologies that can improve the efficiency of personalized public transit and demand responsive systems such as paratransit. This interim report reviews available and emerging ITS technologies that have been deployed or are being considered for this industry. We also conducted a survey of commercially available computer aided dispatching software. We list the numerous features offered by these software packages. Also, included in this interim report is a statistical analysis of travel patterns of a paratransit provider in Los Angeles County. This data analysis will form the basis for our testbed in the second phase of the project. The second phase will compare the performance of a strictly curb-to-curb system with a hybrid system that is a mixture of curb-to-curb and fixed route.

The Effects of Data Inaccuracy on the Performance of Traffic Signal Timing Plans

Thu, 22 Dec 2022 00:00:00 +0000

This paper explores the performance of signal timing plans calibrated with perfect or imperfect information. The arrival information considered include arrival rates and arrival distributions. The study is conducted for different levels of arrival rates and different forms of arrival distributions under a wide range of arrival information inaccuracy, traffic intensity, and intersections with balanced and unbalanced flows.

Our results indicate that the increase in delay, the number of stops, and queue length is in general insignificant when the arrival distribution used to calibrate the optimal timing plan is over- or under-estimated. For the same level of over- or under-estimation, the increase in delay and other measures can be high only when the flow level is very high. The effect, however, is attenuated for overestimation of flow since the cycle length is bounded by a predetermined upper bound. Overall, underestimation of flow appears to be more serious than overestimation...

A Machine Vision Based Surveillance System for California Roads

Tue, 20 Dec 2022 00:00:00 +0000

In this report we address the problem of automation of heavy-duty vehicles. After a brief description of the dynamic model used in our design and simulations, we develop nonlinear controllers with adaptation, first for speed control and then for vehicle follower longitudinal control. We consider both autonomous operation as well as intervehicle communication, and evaluate the performance of our controllers in several different scenarios through simulation.

Variable Message Signs and Link Flow Evaluation: A Case Study of the Paris Region

Tue, 20 Dec 2022 00:00:00 +0000

SIRIUS (Systeme d'Information Routiere Intelligible aux Usagers) is the largest urban field operational test of the advanced traveler information and automated traffic management system in Europe. With variable message signs, SIRIUS has been in operation in the Paris region since December 1992. This study is a preliminary investigation of the effectiveness of the SIRIUS system in traffic management.The concern of the paper is the extent to which drivers respond to real-time traffic information and the consequential changes in link flow under SIRIUS. Time-series traffic data were analyzed to measure changes in mean flow rates at a selected link. The study indicates that variable message signs do influence drivers to choose lesser congested routes when provided with real-time information. Graphical analysis using cumulative arrival curves suggests that diversion behavior is closely associated with information pertaining to the level of congestion. The results of the study indicate...

Bus Lanes/Bus Rapid Transit Systems on Highways: Review of the Literature

Tue, 20 Dec 2022 00:00:00 +0000

This report presents the findings of a study of commercial motor vehicle inspection and screening station practices with a focus on the use of various technologies to help address problems related to safety, security, roadway infrastructure, and air quality. A review of industry literature identified the various types of inspection and screening practices that have been and are being implemented including weight and size management, on-board equipment checking, driver-related violations and cargo monitoring, credential checking, and exhaust emissions monitoring. The review also identified technologies that have been employed as part of these practices as well as an assessment of their performance. The research also involved the use of a survey of State and Provincial Departments of Transportation in North America that have implemented specific practices. Survey findings indicate that to a certain degree a more integrated and multi-practice approach is being taken; a wide array...

A Survey of Value Added Resellers: Private Sector Views on Advanced Traveler Information Markets

Fri, 2 Dec 2022 00:00:00 +0000

This is a case study of publidprivate partnerships for the implementation of TravInfo, an advanced traveler information system for the San Francisco Bay Area. The purpose of the paper is to illuminate private sector views on how the public/private partnership should work in order to successfilly implement TravInfo. This paper reports on the analysis of a series of interviews conducted among those private sector firms who are participating in the federal Field Operational Test of TravInfo. The firms interviewed range from product manufacturers to service providers, including traffic information reporting firms, geographic data collection and dissemination firms and ATIS device distributors. The interview data were analyzed using the cluster analysis concept.

The results of the interviews indicate that the private sector strongly supports a publidprivate partnership and that the private firms believe that the partnership is essential to the success of ATIS deployment; cooperation...

Collecting Road Traffic Data Using ALOHA Mobile Radio Channel

Fri, 2 Dec 2022 00:00:00 +0000

This report proposes a spectrum efficientsolution for transmitting link travel times from vehicles to a central infrastructure. The performance of an ALOHA mobile radio system for this application is studied analytically. The average number of new updates per minute and the expected time lapsed since the latest update of the road traffic situation in a particular street section is obtained. Results show that in an urban environment, a single (cellular) radio channel has sufficient capacity if receivers are located every 5 to 10 km.

The Spatial Evolution of Traffic Under the Two Wave Speed Assumption: A Shortcut Procedure and Some Observations

Fri, 2 Dec 2022 00:00:00 +0000

This paper describes the behavior of traffic in a homogeneous highway according to the hydrodynamic theory, in the special casewhere the flow-density relationship is triangular; i.e. when only two wave velocities exist. It presents an exact formula thatpredicts the vehicle that would be found at position x at time t, given the locations of all the vehicles at time zero. The formula, which does not require identification of the vehicle positions at intermediate times, automatically accounts for the creation and dissipation of any shocks. It can be used to calculate system performance measures such as the flow, speed and density at any future point in time-space and the vehicle travel times. The paper also introduces two graphical procedures. The first one identifies all the vehicle positions along the highway for any fixed t, and the second one identifies the traffic state on all the points in time-space. The second procedure can also be applied to highways that are in homogeneous...

Freight Transportation and Highway Automation: Research on Advanced Technologies for Goods Movement as an Integral Part of the PATH Program

Fri, 2 Dec 2022 00:00:00 +0000

The Program on Advanced Technology for the Highway (PATH), has been established in response to funding by the United States Congress and the California Legislature to demonstrate how "high technology" might be applied to improve highway transportation. PATH's goal, in the short run, is to implement technologies which promise significant relief of acute problemsincluding traffic congestion, air pollution and energy use. Alternative systems of vehicle guidance and control, navigation, propulsion, and communication will be studied and/or developed. The impacts of these systems on highway travel, transportation, the economy and society will be predicted. Researchers envision a new generation of highway transportation ultimately evolving out of these experiments and others like them.

Robust Automatic Steering Control for Look-Down Reference Systems with Front and Rear Sensors

Thu, 1 Dec 2022 00:00:00 +0000

This paper describes a robust control design for automatic steering of passenger cars. Previous studies [l-3] showed that' reliable automatic driving at highway speed may not be achieved under practical conditions with look-down reference systems which use only one sensor at the front bumper to measure the lateral displacement of the vehicle from the lane reference. An additional lateral displacement. sensor is added here at the tail bumper to solve the automatic steering control problem. The control design is performed stepwise: First, an initial controller is determined using the parameter space approach in an invariance plane. This controller is then refined to accommodate practical constraints and finally optimized using the multi-objective optimization program MOPS. The performance and robustness of the final controller was verified experimentally at California PATH in a series of test runs.

Field Deployment and Operational Test of an Agent-based, Multi-Jurisdictional Traffic Management System

Thu, 1 Dec 2022 00:00:00 +0000

This report describes a reinterpretation of how the philosophy underlying the Cartesiusmulti-jurisdictional incident management prototype can be used as an organizing princi-ple for real-world multi-jurisdictional systems. This interpretation focuses on the power ofthe Distributed Problem Solving (DPS) approach Cartesius uses to partition analysis andoptimization functions in the system across jurisdictions. This partitioning minimizes theamount of local information that must be shared between jurisdictions and paves the way fordefining a collection of TMC-to-TMC messages that support the Cartesius DPS perspectivein a manner that respects existing deployments.

Based on this interpretation, the report recommends building a new TMC software agentthat provides operators with a view of the system from Cartesius DPS perspective. This toolwill initially be advisory in nature, providing operators with guidance regarding how localactions are likely to conflict with the actions...

The Naturalistic Driver Model: Development, Integration, and Verification of Lane Change Maneuver, Driver Emergency and Impairment Modules

Thu, 1 Dec 2022 00:00:00 +0000

This report documents work conducted in order to support the development of a driver model. This work consisted of (i) a review of driver models for identifying the possibility to add some functionalities to the current model based on existing models and (ii) the data collection and analysis in order to describe the mechanism of distraction and potentially offer some quantification of its effect on drivers’ behavior and performance.

EasyConnect: Low-Speed Modes Linked to Transit Planning Project

Thu, 1 Dec 2022 00:00:00 +0000

The EasyConnect Low-Speed Modes Linked to Transit Planning Project (TO 5113) project represents the integration of innovative strategies to enhance transit use during the development and construction of a suburban transit oriented development at the Pleasant Hill Bay Area Rapid Transit (BART) District station in the East San Francisco Bay Area. This planning project brings together a unique partnership including small technology businesses, transportation agencies, city and county government, and academia. The project components include the introduction of shared-use low speed mode vehicles and electronic lockers at the proposed TOD. The evaluation of the EasyConnect field operational test (TO 6113-the next phase of this initiative) will provide insights into whether the introduction and integration of low-speed modes and elockers at the Pleasant Hill BART station can significantly increase transit access/use and cost effectively provide a last mile solution.

Travel of Diverse Populations: Literature Review

Thu, 1 Dec 2022 00:00:00 +0000

California is in the midst of a demographic transformation. According to the 2000 U.S. Census, nearly 30 percent of the California population is now foreign-born, more than 50 percent of the population belongs to a minority group, and the elderly (those 65 and older) comprise 11 percent of the population. Demographic forecasts suggest that these patterns will continue. California will continue to attract immigrants from throughout the world and will become increasingly diverse, racially and ethnically, with whites declining as a share of the population from 54 percent in 1995 to 30 to 34 percent in 2025, according to one forecast (Thomas and Deakin 2001). The percentage of seniors will also continue its upward trajectory in the coming decades, reaching over 13 percent by 2025 (Thomas and Deakin 2001). This demographic transformation raises an important question for transportation planners in the state: How can we ensure that the kinds of transportation systems and services...

User Response to the Telephone Advisory Traveler Information System in the San Francisco Bay Area: Based on TravInfo Caller Survey Wave 1

Thu, 1 Dec 2022 00:00:00 +0000

This paper presents the findings of a survey conducted among callers of a San Francisco BayArea telephone information service. A Bay Area traveler information system, TravInfo, has beenin operation since September 1996. In April 1997, a survey of TravInfo callers was conductedover a two-week period. The paper compares the call making and demographic characteristics ofthose who asked for traffic information and of those who asked for transit information. Changesin travel behavior after the calls were made were also investigated. The key findings of the studywere that the people who called for traffic or transit information were satisfied with the service.About one-third of the people who made a trip after calling TravInfo modified their travelbehavior, of which the majority took an alternate route or changed their departure time. Therewas no significant difference between the call making characteristics and the demographicprofiles. A greater proportion of repeat TravInfo customers...

A Multi-channel VANET Providing Concurrent Safety and Commercial Services

Fri, 21 Oct 2005 00:00:00 +0000

One of the key goals of a vehicular ad-hoc network (VANET) is providing sufficient quality of service (QoS) for real-time safety applications while concurrently supporting commercial services. This paper proposes a multi-channel wireless communication architecture and protocol for the scenario where commercial services are provided by roadside infrastructure. This solution extends the IEEE 802.11 wireless LAN protocol to schedule periodic safety messages in a "safety channel". It explicitly supports concurrent non-time-critical communications in separate, non-safety "service channels". Further, it is shown that this arrangement maximizes service channel access time while maintaining the requisite QoS for safety applications. This paper concludes with simulations that confirm the attractive properties of this architecture and protocol.

Effects of Traffic Density on Communication Requirements for Cooperative Intersection Collision Avoidance Systems (CICAS)

Fri, 21 Oct 2005 00:00:00 +0000

Intersection collisions are difficult to mitigate or eliminate by use of ITS technologies for a variety of reasons. These include the complexity of the driving environment and of the driver decision making process at intersections, but also the difficulty of accurately detecting the movements of all potentially conflicting vehicles. Prior research by Calspan-Veridian Engineering (now part of General Dynamics) (1) showed the near impossibility of detecting the relevant information using vehicle-mounted sensor systems. Current research under the IDS program is revealing the challenges associated with detection using infrastructure-based sensor systems. As our understanding of intersection crashes and the performance needs of intersection collision avoidance systems have been improving, so has the interest in cooperative system implementations. In these Cooperative Intersection Collision Avoidance Systems (CICAS), information detected by both vehicle- based and infrastructure-based...

Longitudinal And Lateral Throughput On An Idealized Highway