Vehicle scheduling in a relay point transportation network.

摘要

Transportation, which is the single most dominant cost of distribution accounting for nearly five percent of the total purchase price of a product, is fundamental to the day-to-day functioning of global markets [27]. While the term `transportation' includes a wide variety of modes such as water, truck, rail, and air, vehicle scheduling (the focus of this paper) deals predominantly with long-haul truck transportation both full and less-than-truckloads. Truckload transportation in recent times has seen a dramatic increase in price largely the result of poorly organized truckloads, high truck driver turnover rates, increased federal regulation, and awkwardly organized truck routes. Focusing on the last three segments, vehicle scheduling has been an effective tool in managing transportation costs by improving driver satisfaction and creating order in a world where customers, drivers, and manufacturing companies function in a federally regulated environment.;While most long-haul drivers are not paid by the hour but instead are paid by the mile, federal regulations reducing the number of hours they can drive in turn reduces the number of miles they can travel and thus reduces their pay [26]. In addition, because drivers are only allowed to drive a certain number of hours each day including waiting time according to federal regulations, poorly planned routes and timed pickups and deliveries severely minimizes the amount of time and number of miles a driver can travel. Furthermore, long-haul drivers in general spend little time at home only returning home after a haul or every few weeks. Federal regulations stipulate drivers to shut down their vehicles after so many hours of driving time, cause drivers to require additional time in order to complete a haul which leads to missed delivery deadlines and diminished number of days spent home. As a result of these negative occurrences, drivers begin to feel unsatisfied and disdain toward the driving profession and quit or turnover prompting companies to seek out new drivers. By determining the number of hours a driver can operate a truck during a certain period of time, federal regulations reduce driver efficiency and further press companies to employ additional drivers to meet customer demand. The costs of hiring and training new employees are then passed from the company to the consumers who in turn pay more for their products. This is where vehicle scheduling comes into play.;Customers, whose satisfaction depends primarily on the speed with which they receive their shipments, for the most part, set the vehicle scheduling time constraints for truckload deliveries. Truck drivers, on the other hand, who base their overall satisfaction according to their pay and the frequency in which they are allowed to return home, will determine the standard for vehicle routing nightly home arrival. Meanwhile, manufacturing companies who wish to reduce expenses by retaining drivers will determine the vehicle scheduling objective.;Within this thesis, the previous endeavors to control truckload transportation will be highlighted, the use of relay points to increase driver home time will be explained, and a new vehicle scheduling model to meet federal regulation as well as provide appropriate departure and arrival times will examined.