Donald R. Drew

AUTOMATIC MEASUREMENT OF TRAFFIC VARIABLES FOR INTELLIGENT TRANSPORTATION SYSTEMS APPLICATIONS

This paper presents a methodology for automatic measurement of major traffic variables for Intelligent Transportation Systems applications (ITS) in real-time. It is an illustration of the integration of theory, measurement, and application. Such effort has been overlooked since the advent of ITS due to the number of different disciplines involved. The inductive methodology adopted in this study includes the development of a new dynamic traffic flow model which is based on the characteristics of the stochastic vehicle counting process and the principle of conservation of vehicles. The model estimates spatial traffic variables, such as link travel times, as a function of time directly from flow measurements. It satisfies the traffic dynamics through a new form of the equation of conservation of vehicles. Analysis results show that the estimates are in qualitative and quantitative agreement with empirical data aggregated at 2-min intervals. The advantages of this inductive model include real-time applicability, computational efficiency, and transportability over traditional deductive models such as continuum flow models. It appears to be promising in applying to real world problems.

Using simulation to understand the impact of deferred maintenance

Understanding the impact of deferred maintenance on a highway system can help policy makers and transportation planners in the decision process on how to best utilize limited resources to provide for an areas total infrastructure needs. This paper presents the development of a framework and methodology to use dynamic simulation to understand and quantify the impact of deferred maintenance and the effect on user and non-user benefits. This simulation will allow the testing of policies or assumptions for their impact over time, in order to gain insight into the problem solution. A hypothetical region is used to demonstrate the use of the framework, and three possible measures of effectiveness, total net benefits per capita, revenues less expenditures, and benefit-cost ratio, are introduced that could be utilized to help decision-makers understand the impact of various maintenance funding rates on different interest groups being served within the community. The model can be calibrated to a region to provide specific impact information for that location.

Scenariopolis: the civil engineering systems policy research laboratory

Abstract This paper describes a system dynamics model of a hypothetical region. The region provides an environment for three typical civil engineered systems; water resource, sewage treatment and urban transportation. The interaction of the key parameters of each system within the system, as well as among the systems, are examined through scenario analysis using simulation and analytical techniques.

Systems Dynamics Modeling of Air Warfare

The use of gaming to study contemporary warfare has evolved rapidly in recent years. Particularly important strides were taken during the 1960’s and 1970’s with advances in computer technology and the development of broader ranges of subject matter. The past two decades have seen a tremendous expansion in the role and influence of computer models as “policy assisting” devices — first in the analysis of national security issues, and now for the analysis of problems arising throughout the entire affairs of Government.