Mark A Miller

Effects of Adaptive Cruise Control Systems on Highway Traffic Flow Capacity

The effects on traffic flow of increasing proportions of both autonomous and cooperative adaptive cruise control (ACC) vehicles relative to manually driven vehicles were studied. Such effects are difficult to estimate from field tests on highways because of the low market penetration of ACC systems. The research approach used Monte Carlo simulations based on detailed models presented in the literature to estimate the quantitative effects of varying the proportions of vehicle control types on lane capacity. The results of this study can help to provide realistic estimates of the effects of the introduction of ACC to the vehicle fleet. Transportation system managers can recognize that the autonomous ACC systems now entering the market are unlikely to have significant positive or negative effects on traffic flow. An additional value of studying ACC systems in this way is that these scenarios can represent the first steps in a deployment sequence that will lead to an automated highway system. Benefits gained at the early stages in this sequence, particularly through the introduction of cooperative ACC with priority access to designated (although not necessarily dedicated) lanes, can help support further investment in and development of automated highway systems.

Modeling Effects of Driver Control Assistance Systems on Traffic

A set of mathematical models is defined to predict the effects of emerging driver control assistance systems such as adaptive cruise control (ACC) on traffic flow dynamics and capacity. It is important to understand these effects in order to ensure that ACC systems are implemented in ways that improve, rather than degrade, traffic conditions. Existing traffic models were not designed for, and are not suitable for, this purpose, so it has been necessary to develop a new family of simulation models incorporating the key elements of driver behavior and control system design that will affect traffic flow dynamics and capacity. Example outputs from simulation validation test cases are illustrated and explained to show that the models are producing reasonable results.

Traveler Information Tool with Integrated Real-Time Transit Information and Multimodal Trip Planning: Design and Implementation

The chief objective of the PATH2Go multimodal traveler information application is to improve the accessibility and the quality of real-time traveler information and to make transit a known and viable choice for travelers. PATH2Go was developed as part of a field test on the US-101 corridor in the San Francisco Bay Area of California, with the primary hypothesis that travelers would benefit from real-time multimodal traveler information and therefore would be likely to consider using transit. PATH2Go integrates a web-based multimodal trip-planning tool that uses real-time transit, traffic, and parking information; a web-based search tool that finds real-time information about transit arrivals and schedules; and a mobile application that provides personalized en route transit trip information. PATH2Go integrates these major components of traveler information in one platform and makes real-time information easily accessible to travelers. The PATH2Go system architecture and major design considerations are described, and enabling technologies–including the Global Positioning System (GPS) fusing algorithm and a scenario-parsing algorithm based on GPS location data–are introduced.

Direct Ridership Model of Bus Rapid Transit in Los Angeles County, California

A direct ridership model (DRM) for predicting bus rapid transit (BRT) patronage in Southern California is estimated. Attributes of bus stops and their surroundings constitute the data observations of DRMs and enable a fairly fine-resolution analysis to be carried out on factors that influence ridership. The best-fitting DRM revealed that service frequency strongly influenced BRT patronage in Los Angeles County. High intermodal connectivity, with both feeder bus routes and rail transit services, also significantly induced BRT travel. As population densities increased, so did BRT patronage, all else being equal. For exclusive-lane BRT services, high employment densities were also associated with high daily boardings. The strong statistical fit of the model bodes well for DRM as a platform for estimating BRT patronage in coming years.

BUS RAPID TRANSIT INSTITUTIONAL ISSUES: THE ROUTE FROM RESEARCH TO EXPERIENCE

The institutional aspects of bus rapid transit (BRT) are investigated through a macroscopic examination and a survey of members of FTA’s BRT Consortium and several Canadian transit properties. The macroscopic examination resulted from a literature review, project team brain-storming meetings, and input from FTA’s BRT staff. Several dozen issues were identified and grouped into nine categories that formed the basis of the survey—intergovernmental and interorganizational; intratransit property; political; public relations and marketing; funding and finance; labor; safety and liability; planning and land use; and the physical environment. Specific issues were identified that, overall, are both the most important and most difficult to resolve—local and business community opposition to the removal of, or restrictions on, parking spaces for use; availability and acquisition of right-of-way or physical space; integration of multiple priorities, objectives, and agendas; concerns over longterm funding commitments to BRT; BRT effects on roadway operations; finding political champions to support BRT; gaining community support for transit-oriented development; and educating the public about BRT and managing perceptions and expectations. Although a small set of opinions was obtained, the investigation and analysis of survey responses was based on the insight and expertise of individuals who have experienced these institutional issues. This study should offer guidance to anticipate future problems and develop strategies to resolve them.

Evaluation of lane-assist systems for urban transit operations

This paper describes the operational benefits that can be achieved by the use of two forms of lane-assist systems on urban transit buses, and compares them with the costs of implementing lane assistance. Evaluations were done for precision docking and for automatic steering control under the real-world conditions of downtown Chicago, and these systems were found to have large benefit/cost ratios in both near-term and long-term applications.

Framework for Deployment Planning of Bus Rapid Transit Systems

Bus rapid transit (BRT) systems combine vehicles, stations, running ways, and intelligent transportation system elements into a fully integrated system with a unique identity. It has great flexibility in incremental deployment of these BRT elements. Proposed is a deployment planning framework that provides, in a sequence of steps, a general structure for optimal deployment of BRT systems. This framework and its formulation, once operationalized, would provide transit agencies a practical tool for determining the optimal deployment strategy or strategies given budgetary, institutional, and other types of constraints associated with the corridor for which they have decided to deploy BRT. A case study example is provided to illustrate how the proposed framework would be used.

Highway automation: System modeling for impacts analysis

Highway automation technologies have been proposed in an attempt to ameliorate the urban problem of congestion and, to a lesser extent, air pollution. The methodology developed to analyze the impacts of an automated highway system in the Southern California region in 2025 is addressed in this paper. An automated highway system scenario is selected from several alternatives based on sensitivity analyses that allow for variability in network location, total network miles, and market penetration of vehicles equipped with automation features.

Integration of Automated Highway Systems into Existing California Freeways

Automated Highway Systems (AHS) have the potential for providing improvements over conventional freeways in terms of vehicle throughput, traffic safety, driver comfort, and environmental impacts. Although a number of AHS deployment concepts have been presented in the literature, few studies have attempted to evaluate the issues and risks associated with alternative deployment concepts.(1–3) This research is devoted to an investigation of the issues and risks associated with the integration of AHS facilities into existing California freeways, in both urban and rural environments.

LESSONS LEARNED FROM A REVIEW OF EVALUATIONS OF AUTOMATED HIGHWAY SYSTEMS

A review of the literature pertaining to automated highway systems (AHSs) has resulted in the documentation of lessons learned from major European and U.S. evaluations of AHSs that cover the AHS benefit assessment process. The lessons learned will be assimilated into an evaluation framework and plan, with the aim of adopting those aspects of past and present evaluations and avoiding known pitfalls. At the same time, key findings of previous AHS studies have been documented. The three products of the literature survey are as follows: a characterization of the coverage of nine categories of AHS evaluations; the identification of a sequence of evaluation phases, as planned for in nine major AHS studies; and the documentation of critical inputs to a plan for evaluating AHS concepts.