H.-S. Jacob Tsao

Constraints On Initial Ahs Deployment And The Concept Definition Of A Shuttle Service For Ahs Debut

This paper then proposes a shuttle van service as the initial deployment automated highway systems (AHS) target. The freeway portion of the trip is fully automated and a professional driver is required for off-freeway driving. The author then discusses its many advantages from the view point of deployment issues aforementioned. Some possible issues of this initial deployment strategy and areas of future research will also be pointed out.

Analytical Models for Vehicle/Gap Distribution on Automated Highway Systems

Highway congestion has in recent years become a pervasive problem for urban and suburban areas alike. The concept of Automated Highway Systems is based on the belief that integration of sensing, communication, and control technologies into vehicles and highways can lead to a large improvement in capacity and safety without requiring a significant amount of additional highway right-of-way. A fundamental determinant of Automated Highway Systems capacity is the vehicle-following rule, the rule that governs the behavior of vehicles traveling along a common lane (e.g., the spacing between any two longitudinally adjacent vehicles). Vehicle following affects the longitudinal capacity (achievable flow within a lane), the lateral capacity (achievable flow between lanes) and the conflicting relationship between the longitudinal flow and lateral capacity. The issues are investigated by developing probabilistic models for vehicle/platoon and gap distributions, for vehicles that travel in platoons, in slots, or as free-agents. Mathematical models are also developed to estimate the completion time of a lane change, which can be used as a surrogate for the lateral capacity. Numerical results for the three major vehicle-following rules and their comparison are also provided.

STAGE DEFINITION FOR AHS DEPLOYMENT AND AN AHS EVOLUTIONARY SCENARIO

This paper proposes an approach to defining evolutionary scenarios for the deployment of an Automated Highway System (AHS). Six dimensions of deployment difficulties are identified: technology, infrastructure, human factors, vehicle manufacturing and maintenance, insurance, and public will.

A Framework for Evaluating Deployment Strategies for Intelligent Transportation Systems

Because Intelligeni Transportation Systems (ITS) R&D is performed for the ultimate depolyment in the real world, deployment issues may limit design options for ITS operating concepts and technologies and, hence, can be viewed as constraints on ITS R&D. Therefore, ITS deployment issues must be studied at the outset of the R&D process. This paper develops a framework to help anticipate, recognize and organize such issues. The findings can be used by ITS researchers in developing deployable ITS operating concepts and the enabling technologies and by ITS promoters in deploying ITS operating concepts and technologies having been developed already. Based on a focus on decisions and decision makers impacting the deployment of ITS user services, we attempt to“derive”the issue dimensions of such a framework. The resulting eight dimensions of ITS deployment issues are: need, solution/opportunity, decision maker, decision making, decision influencing, time, risk management, and synergy.Because Intelligeni Transportation Systems (ITS) R&D is performed for the ultimate depolyment in the real world, deployment issues may limit design options for ITS operating concepts and technologies and, hence, can be viewed as constraints on ITS R&D. Therefore, ITS deployment issues must be studied at the outset of the R&D process. This paper develops a framework to help anticipate, recognize and organize such issues. The findings can be used by ITS researchers in developing deployable ITS operating concepts and the enabling technologies and by ITS promoters in deploying ITS operating concepts and technologies having been developed already. Based on a focus on decisions and decision makers impacting the deployment of ITS user services, we attempt to“derive”the issue dimensions of such a framework. The resulting eight dimensions of ITS deployment issues are: need, solution/opportunity, decision maker, decision making, decision influencing, time, risk management, and synergy.

Traffic Control for Automated Highway Systems: A Conceptual Framework

This paper proposes a conceptual framework for designing a traffic control scheme. It adopts a top-down approach to defining major design steps starting with high-level feature definition. With the desired features defined, the top-down approach then identifies and defines moves and related planning and movement functions that are required for supporting the desired features. The paper takes a systems view and identifies the safety issues regarding the movement coordination of the large number of vehicles on an Automated Highway System (AHS).

A method for identifying a minimal set of test conditions in 2 k experimental design

A primary task of the analysis of a 2k factorial design is to estimate the 2k unknown effects/interactions. When some of these interactions are known to be zero or negligible, a full 2k factorial design may no longer be necessary. In general, when only M effects/interactions are non-zero, only M test conditions are required for the estimation. Both fractional factorial design and Taguchis method typically require 2n test conditions, n = 2,3,4 ...., and hence do not take full advantage of this fact. We first demonstrate that when there are M non-zero effects/interactions in a 2k model, not every set of M test conditions out of the 2k test conditions would suffice for estimating the M unknowns. We then propose an algorithm to find a set of M test conditions that suffices. The proposed algorithm can be used to identify all such minimal sets of test conditions. In this paper, we report two such minimal sets for all possible scenarios of interest for 23 and 24 designs. If the assumed zero interactions are indeed zero, confounding is not an issue. Moreover, such assumptions can be double-checked via ANOVA.

Forward Apportionment of Censored Counts for Discrete Nonparametric Maximum Likelihood Estimation of Failure Probabilities

Empirical cumulative lifetime distribution function is often required for selecting lifetime distribution. When some test items are censored from testing before failure, this function needs to be estimated, often via the approach of discrete nonparametric maximum likelihood estimation (DN-MLE). In this approach, this empirical function is expressed as a discrete set of failure-probability estimates. Kaplan and Meier used this approach and obtained a product-limit estimate for the survivor function, in terms exclusively of the hazard probabilities, and the equivalent failure-probability estimates. They cleverly expressed the likelihood function as the product of terms each of which involves only one hazard probability ease of derivation, but the estimates for failure probabilities are complex functions of hazard probabilities. Because there are no closed-form expressions for the failure probabilities, the estimates have been calculated numerically. More importantly, it has been difficult to study the behav...

A STAGGERED-DIAMOND DESIGN FOR AUTOMATED/MANUAL-HOV HIGHWAY-TO-HIGHWAY INTERCHANGES

This paper proposes a staggered-diamond design for automated connector ramps for an Automated Highway System (AHS). After describing the main features of this design, the paper discusses the constraints on AHS operational design imposed by the requirement for continuous automated highway-to-highway driving. The constraints on AHS evolution due to the same requirement are then discussed.