主题：Alternative service schemes for busy transit corridors
Dr. Gu is now an assistant professor at the Department of Electrical Engineering, the Hong Kong Polytechnic University. He received his Ph.D. in Civil & Environmental Engineering from University of California, Berkeley in 2012. He also received his B.S. and M.Eng. degrees in Civil Engineering from Tsinghua University (Beijing, China) in 2002 and 2005; and his M.Sc. (in Industrial Engineering & Operations Research) and M.A. (in Economics) degrees from UC Berkeley in 2010 and 2011.
Dr. Gu’s research interests span over public transit systems, multimodal urban transportation systems, freeway traffic operations, queueing systems, and infrastructure systems management. He is especially interested in how various transportation modes including cars, buses, rail, and bicycles interact in urban networks, and how to optimally design and manage such a multimodal urban transportation system for the benefit of all.
His awards include a Gordon F. Newell Award for Excellence in Transportation Science (granted by the Faculty of Transportation Engineering at UC Berkeley) and a Chinese Government Award for Outstanding Self-Financing Students Abroad.
Transit systems in which buses or trains always visit each and every stop along corridors are compared against those that feature two alternative vehicle-dispatching schemes. The alternatives entail so-called skip-stop and express/local services. Continuum models found in the literature are expanded so that the alternatives could be compared under a wider array of options. Comparisons are separately drawn for systems that feature buses, BRT and metro-rail trains, both for cities that are wealthy and for those that are not. Idealizations in regard to travel demand and route symmetry are assumed in pursuit of insights useful for high-level planning.
In a first round of parametric comparisons, optimally-designed all-stop systems are presumably converted to furnish the alternative strategies instead. Conversions are made without altering the stop locations of the original systems, as would occur when relocating stops is a prohibitively expensive option in the conversion process. The converted systems are thus hampered by stop locations that are sub-optimal for the alternative schemes that they support. Still, the conversions often bring lower generalized costs than do their optimally-designed predecessor systems. Enhanced versions of skip-stop service are found most often to be the lowest-cost options. Estimated savings are greatest when travel demand and the patrons’ average trip lengths are large. Savings of as much as 10% are estimated in those cases. When demands and trip lengths are especially large, skip-stop service is found the only means to prevent the steady growth of residual patron queues at stops.
In a second round of comparisons, alternative schemes are designed in fully-optimized fashion from scratch, and are thus free from any remnants of any earlier all-stop systems. Once again, alternative dispatching schemes often produce the lowest costs, with skip-stop service again emerging as the best option for the widest range of conditions. Estimated savings in these instances reach 30%. Skip-stop service is also found to be especially suitable for optimally-designed BRT systems. These often outperform optimized rail systems when the latter operate in all-stop fashion. Rail nonetheless emerges as the preferred mode when travel demand is especially high. In those instances, optimized express/local rail services are found to deliver the lowest generalized costs.