THESIS
2021
1 online resource (xiv, 178 pages) : illustrations (some color)
Abstract
This thesis studies a zonal-based flexible bus service (ZBFBS), which is a class of demand
responsive transit (DRT) service considering passenger demands’ spatial (origin-destination or
OD) and volume stochastic variations. It is then extended to incorporate price and service
elasticity and passenger travel time. Finally, time-dependent demand and time-dependent travel
time are taken into account while a precise schedule for the ZBFBS is constructed.
Dividing the service area into zones, service requests are aggregated by zonal OD pairs,
time window constraints, and the number of passengers per request. Three two-phase stochastic
problems with recourse are formulated, including a frequency-based model minimizing the cost,
a frequency-based model maximizing the profit minus detour cost,...[
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This thesis studies a zonal-based flexible bus service (ZBFBS), which is a class of demand
responsive transit (DRT) service considering passenger demands’ spatial (origin-destination or
OD) and volume stochastic variations. It is then extended to incorporate price and service
elasticity and passenger travel time. Finally, time-dependent demand and time-dependent travel
time are taken into account while a precise schedule for the ZBFBS is constructed.
Dividing the service area into zones, service requests are aggregated by zonal OD pairs,
time window constraints, and the number of passengers per request. Three two-phase stochastic
problems with recourse are formulated, including a frequency-based model minimizing the cost,
a frequency-based model maximizing the profit minus detour cost, and a schedule-based model
maximizing the profit. In phase-1, given the reliability requirements, the operating profit of
flexible bus services is maximized for frequency-based and schedule-based models by vehicle-to-route assignment before demand realization. In phase-2, passengers are assigned to vehicles
to minimize the expected ad hoc service cost. Demand volume reliability and detour time
reliability are introduced to ensure the quality of the services and separate the problem into two
phases for efficient solutions. The reliabilities are then optimized by a gradient-based approach
to optimize for the objective. Relaxations, heuristics, and alternative solution algorithms are
proposed to enhance the performance of planning ZBFBS.
Finally, a bi-level framework is proposed to jointly optimize the zonal design and flexible
bus service strategy. Numerical examples are provided to illustrate the relationship between
vehicle capacity, profit, demand volume, and zonal design, and that the optimal zone dimension
is positively correlated with demand volume. Also, the improvements by using heuristics,
relaxations, and schedule-based planning are elaborated. Moreover, the zonal design and
ZBFBS strategy are validated in instances constructed based on the real data in Chengdu, China.
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