Some Computational Insights on the Optimal Bus Transit Route Network Design Problem

The objective of this paper is to present some computational insights based on previous extensive research experiences on the optimal bus transit route network design problem (BTRNDP) with zonal demand aggregation and variable transit demand. A multi-objective, nonlinear mixed integer model is developed. A general meta-heuristics-based solution methodology is proposed. Genetic algorithms (GA), simulated annealing (SA), and a combination of the GA and SA are implemented and compared to solve the BTRNDP. Computational results show that zonal demand aggregation is necessary and combining metaheuristic algorithms to solve the large scale BTRNDP is very promising

Vehicle weight surveys and in-motion weighing

The need for vehicle weight data in planning and designing highway facilities has historically been satisfied by stopping selected vehicles at specially prepared roadside sites and weighing each wheel of the vehicle on portable scales. This survey technique has been an expense and a safety hazard both to the surveying agency and to the road users. A recently developed system for weighing highway vehicles in-motion eliminates all user costs and reduces many of the traffic hazards and personnel expenses which have previously been inherent in static weight surveys. Field tests of the in-motion weighing system indicate that accuracy comparable to that of conventional static wheel weighing devices is feasible. A revised vehicle weight sampling program, which incorporates in-motion weighing, has been designed for the State of Texas. Included in the design of the new program is an evaluation of the number of necessary survey sites, sample sizes, and a study of timewise variations in vehicle weights. The economic effects of utilizing conventional static or in-motion weighing techniques, in the new program, are analyzed through a comparative cost analysisCivil, Architectural, and Environmental Engineerin

Mechanistic-Empirical Study of Effects of Truck Tire Pressure on Pavement: Measured Tire-Pavement Contact Stress Data

Truck tire pressure plays an important role in the tire–pavement interaction process. As a traditional approximation method in many pavement studies, tire–pavement contact stress is frequently assumed to be uniformly distributed over a circular contact area and simply equal to the tire pressure. However, recent studies have demonstrated that the tire–pavement contact stress is far from uniformly distributed. In this study, measured tire–pavement contact stress data were input to a finite element program to compute pavement immediate responses for three tire configurations: single tires, dual tires, and dual-tire tandem axles. Computed critical pavement responses were input to pavement distress transfer functions to analyze further the effects of tire inflation pressure on pavement performance. Two asphalt concrete pavement structures—a thick pavement and a thin pavement—were investigated. Pavement responses at selected locations in the pavement structures were computed by the finite element program using the measured tire–pavement contact stress data and compared with the results predicted by a multilayer program using the traditional uniform contact stress method. The computation results showed that the multilayer program and the traditional tire model tend to overestimate the horizontal tensile strains at the bottom of the asphalt concrete and underestimate the vertical compressive strains at the top of the subgrade. Prediction of effects of tire pressure on pavement performance shows that increased tire pressure results in increased pavement distress due to both cracking and rutting and that tire inflation pressure is also related to the shape of pavement ruts

Traveler Path Choice During Freeway Closure

Construction activities and numbers of related work zones on urban freeways have grown significantly. The most problematic work zones occur on roads that are already fully loaded with traffic. The impact of work zones on mobility and safety makes success of the traffic control plan vital. Full freeway closures are sometimes implemented to expedite project completion and thereby reduce the cumulative impact of construction on travelers. Traffic diversion strategy is one way to improve the management of traffic and reduce user costs. An effective diversion plan makes drivers become aware of likely work zone delays and available alternate routes increasing the chances that they will choose alternate routes. Construction on the SH-71/IH-35 interchange required complete closure of all IH-35 main lanes. IH-35 is an important business corridor, conveniently connecting four large Texas cities, as well as, facilitating trade between Mexico and the United States. A parallel route, the SH-130 toll road, was made free to travelers during those closures. The purpose of this paper is to investigate driver route switching behavior during IH-35 closure and explore options for relieving delays on IH-35 during future closures. The Austin highway network was analyzed. However, usage of SH-130 was less than anticipated, and there was significant traffic queuing on IH-35 at the work zone. Analysis was based on integrating data from all available sources. In order to compare conditions of a non-closure weekend to the closure weekend, five recent months were considered

Research report (Southwest Region University Transportation Center (U.S.))

Report exploring how the residents of Austin, Texas would respond to a Bus-on-Shoulder operation on local freeways, which allows buses to use the freeway shoulder as a passing lane