Michael Cassidy | Searcharxiv

arXiv2020

Planning Skip-Stop Transit Service under Heterogeneous Demands

Transit vehicles operating under skip-stop service visit only a subset of the stops residing along a corridor. It is a strategy commonly used to increase vehicle speeds and reduce patron travel times. The present paper develops a continuous approximation model to optimally design a select form of skip-stop service, termed AB-type service. The model accounts for spatially-heterogeneous demand patterns. An efficient heuristic is developed to obtain solutions. These are shown to be near-optimal for a variety of numerical examples. Results also indicate that optimal AB-type designs outperform optimized all-stop service in a variety of cases. The AB-type service is found to be especially competitive when travel demands are high, trip origins are unevenly distributed along a corridor, and patrons have relatively high values of time. In these cases, AB-type service is found to reduce system costs by as much as 8%.

math.OC↗

arXiv2019

Achieving higher taxi outflows from a congested drop-off lane: a simulation-based policy study

We examine special lanes used by taxis and other shared-ride services to drop-off patrons at airport and rail terminals. Vehicles are prohibited from overtaking each other within the lane. They must therefore wait in a first-in-first-out queue during busy periods. Patrons are often discharged from vehicles only upon reaching a desired drop-off area near the terminal entrance. When wait times grow long, however, some vehicles discharge their patrons in advance of that desired area. A train station in Eastern China is selected as a case study. Its FIFO drop-off lane is presently managed by policemen who allow taxis to enter the lane in batched fashion. Inefficiencies are observed because curb space near the terminal often goes unused. This is true even when supplemental batches of taxis are released into the lane in efforts to fill those spaces. A microscopic simulation model of a FIFO drop-off lane is developed in-house, and is painstakingly calibrated to data measured at the study site. Simulation experiments indicate that rescinding the FIFO lane's present batching strategy can increase taxi outflow by more than 26 percent. Further experiments show that even greater gains can be achieved by batching taxis, but requiring them to discharge patrons when forced by downstream queues to stop a prescribed distance in advance of a desired drop-off area. Further gains were predicted by requiring the lead taxi in each batch to discharge its patron only after travelling a prescribed distance beyond a desired location. Practical implications are discussed in light of the present boom in shared-ride services.

stat.AP↗