Advanced transportation economic development

The end of the cold war and confrontational politics of the eastern and western worlds have raised the possibility that resources formerly targeted toward military systems and options may be turned towards global lifestyle improvements [OTA, 1993]. Transportation has been one of the fields proposed as a likely candidate for both improvements and jobs. It is not possible to address economic development in the context of all transportation in one essay. For this reason I am only addressing the issues of economic development associated with mass transportation characteristic of urban and interurban environments. Realigning former defense resources to mass transit requires careful consideration of market conditions. According to economic survey data published by the Economic Roundtable in Los Angeles, there are currently less than 40,000 manufacturing jobs in the U.S. rail transportation industry [Drayse, 1993]. The same survey pointed out a severe mismatch between the skill base required by the rail industry and available defense technology resources. There exists no large base of unsatisfied demand in the rail market, therefore development of a large number of jobs is not likely if the approach is simply to introduce additional competing resources into a traditional market [Monitor, 1993].     

A real-time traffic signal control system: architecture, algorithms, and analysis

The paper discusses a real-time traffic-adaptive signal control system referred to as RHODES. The system takes as input detector data for real-time measurement of traffic flow, and “optimally” controls the flow through the network. The system utilizes a control architecture that (1) decomposes the traffic control problem into several subproblems that are interconnected in an hierarchical fashion, (2) predicts traffic flows at appropriate resolution levels (individual vehicles and platoons) to enable pro-active control, (3) allows various optimization modules for solving the hierarchical subproblems, and (4) utilizes a data structure and computer/communication approaches that allow for fast solution of the subproblems, so that each decision can be downloaded in the field appropriately within the given rolling time horizon of the corresponding subproblem. The RHODES architecture, algorithms, and its analysis are presented. Laboratory test results, based on implementation of RHODES on simulation models of actual scenarios, illustrate the effectiveness of the system.     

The combined effect of rain and wind on air–water gas exchange: A feasibility study

A series of experiments were conducted at University of Delaware's Air–Sea Interaction Laboratory to examine the combined effects of rain and wind on air–water gas exchange. During this study, ASIL WRX I, a combination of 3 rain rates and 4 wind speeds were used, for a total of 12 different environmental conditions. The SF₆ evasion method was used to determine the bulk gas transfer velocities, and airside profiles of wind and CO₂ were used to estimate flux–profiles of momentum and carbon dioxide. In addition to measurements of fluxes with and without rain in a wind–wave boundary layer, measurements of wave properties were also obtained. Rain is shown to alter the wind profile in the flume, and dampen surface waves. Also, SF₆ evasion indicates that with the present experimental setup, for most of the experimental conditions, rain and wind combine linearly to influence air–water gas exchange. Flux–profile relationships for marine atmospheric boundary layers, which were performed to scale up to field measurements, were explored by a comparison between SF₆-derived bulk fluxes and airside CO₂ profile measurements.     

A journey from adversary to partnership bus reform in NSW

This paper continues to debate the importance of understanding in the NSW Bus reform process of the relationship between central agencies, service providers, the academic community, key consultants and contractors within the setting of the transport service organisation framework. Sydney is a modern city with heavy rail, light-rail, monorail and an extensive Harbour, with bus services owned by Government as well as private interests. The paper addresses the case for reforms, the approach taken, competition policy, the subsequent development of partnerships, performance of the regulator, passenger benefits, growth and the differences between Metropolitan/Outer Metropolitan and Regional and Rural bus services.     

A comparison of user-optimum versus system-optimum traffic assignment in transportation network design

In this report, we compare the computational efficiency and results of solving two alternative models for the problem of determining improvements to an urban road network. Using a 1462 link, 584 node test network of the north Dallas area, we compare a model which assumes user-optimum behavior of travelers with a model which assumes system-optimum flows. Both of these models allow improvements to the road network to take on any nonnegative value, rather than requiring discrete improvement values. Investment costs are modeled by functions with decreasing marginal costs. Unfortunately, the user-optimum model, which is much more realistic than the system-optimum one, normally cannot be solved optimally. However, the simpler system-optimum model can be optimally solved, provided that investment costs are approximated by linear functions. Thus, for this network design problem we compare an accurate representation which can be solved only approximately with an approximate representation which can be solved optimally. Our computational testing showed that the system-optimum model produces solutions as good as those from the user-optimum model, and thus seems justified when favored by other considerations, such as ease of coding, availability of “canned” programs, etc.