USING GLOBAL POSITIONING SYSTEM TO IMPROVE SCHOOL BUS ROUTING AND SCHEDULING

School bus routing and scheduling in North Carolina are completed by using the transportation information management system (TIMS), according to state legislative mandate. TIMS uses an optimization algorithm to generate acceptable route alternatives to best serve the transported students and to minimize the required number of buses. This algorithm uses link travel times and speeds encoded in the geocode (digitized map) to determine the routes for each school bus in the state. The speeds and travel times used by TIMS have no mathematical basis and have not been calibrated for conditions in North Carolina. The encoded speeds are simply reductions of the posted speed limit to account for student stops and the bus\u27s general inability to reach the posted speed. There is a need for models that can accurately estimate link travel times and student loading times so that TIMS can provide better estimates of optimal routes. On-board mobile Global Positioning System equipment was used on several school bus routes throughout the state to collect the data necessary for model development and validation. Two student loading time models were developed: a general model that can be used in an urban, a suburban, or a rural area, and an urban-specific model, which involves fewer predictor variables. Link travel-time models were developed according to the two most pertinent factors: link length and traffic control device type at the link\u27s end. Model validation was successful, and now more-efficient school bus routes can be developed because of more-accurate geocode speed and travel-time estimates

URBAN TRANSPORTATION IN THE PEOPLE\u27S REPUBLIC OF CHINA

China\u27s rapid modernization has brought urban traffic problems typical of the world\u27s major cities. The article describes how this has occurred with very little auto traffic. Rigorous applications of traffic systems management are being used, but the conflicts between motorized and nonmotorized transit make alleviation of congestion a near impossible task. This article reviews urban transportation demand characteristics and urban transportation system performance, and gives examples of strategies adopted by different cities to meet local needs. The techniques described are as follows: increase the physical capacity of the road system; improve public transportation performance; expand the role of urban rail systems; improve the flexibility of public and private transportation services to meet the needs of both visitors and residents; improve facilities for cyclists; and increase vehicle operator training and education

AN USER-OPTIMAL ROUTE CHOICE MODEL WITH ASYMMETRIC COST FUNCTIONS INCORPORATING INTERSECTION-RELATED TRAVEL TIMES.

This report describes a traffic assignment model which is innovative in two respects as compared with models conventionally used in practice. First, each turning movement in the street intersections of the network is represented by a travel time-flow relationship; conventional models represent only approach travel times and flows, although turning movements may be accounted for. Second, the travel times for each turning movement are determined as a function of all flows in the intersection as well as the appropriate cycle time and green splits for those flows. Such cost functions are termed asymmetric because of their mathematical properties. In conventional models, each link's travel time depends only on that link's flow. This model is implemented and solved for a small street network for St. Charles, Illinois. To the authors' knowledge, it is the first implementation of such a model with realistic link functions and a real network. The report describes how the link travel time-flow functions were estimated statistically from simulated intersection operations. Then, the experience with the solving model computationally is documented. A lengthy discussion of future research directions concludes the report