90B06 Transportation, logistics
Refine
Keywords
- column generation (3)
- Rapid Branching (2)
- rapid branching (2)
- Bundle Method (1)
- Column Generation (1)
- Container terminal (1)
- Hypergraph Modeling (1)
- Integer Programming (1)
- Integer programming (1)
- Optimization (1)
Line planning is an important step in the strategic planning
process of a public transportation system. In this paper, we discuss an
optimization model for this problem in order to minimize operation costs
while guaranteeing a certain level of quality of service, in terms of
available transport capacity. We analyze the problem for path and tree
network topologies as well as several categories of line operation that
are important for the Quito Trolebus system. It turns out that, from a
computational complexity worst case point of view, the problem is hard in
all but the most simple variants. In practice, however, instances based
on real data from the Trolebus System in Quito can be solved quite well,
and significant optimization potentials can be demonstrated.
We introduce new elevator group control algorithms that can be implemented to be real-time compliant on embedded microcontrollers. The algorithms operate a group of elevators in a destination call system, i.e. passengers specify the destination floor instead of the travel direction only. The aim is to achieve small waiting and travel times for the passengers. We provide evidence, using simulation, that the algorithms offer good performance. One of our algorithms has been implemented by our industry partner and is used in real-world systems.
The line planning problem is one of the fundamental problems in strategic planning of public and rail transport. It consists in finding lines and corresponding frequencies in a network such that a giv en demand can be satisfied. There are two objectives. passengers want to minimize travel times, the transport company wishes to minimize operating costs. We investigate three variants of a multi-commo dity flow model for line planning that differ with respect to passenger routings. The first model allows arbitrary routings, the second only unsplittable routings, and the third only shortest path rou tings with respect to the network. We compare these models theoretically and computationally on data for the city of Potsdam.
This paper concerns the problem of operating a landside container exchange area that is serviced by multiple semi-automated rail mounted gantry cranes (RMGs) that are moving on a single bi-directional traveling lane. Such a facility is being built by Patrick Corporation at the Port Botany terminal in Sydney. The gantry cranes are a scarce resource and handle the bulk of container
movements. Thus, they require a sophisticated analysis to achieve near optimal utilization. We present a three stage algorithm to manage the container exchange facility, including the scheduling of cranes, the control of associated short-term container stacking, and
the allocation of delivery locations for trucks and other container transporters. The key components of our approach are a time scale decomposition, whereby an integer program controls decisions across a long time horizon to produce a balanced plan that is fed to a series of short time scale online subproblems, and a highly efficient space-time divisioning of short term storage areas.
A computational evaluation shows that our heuristic can find effective solutions for the planning problem; on real-world data it yields a solution at most 8% above a lower bound on optimal RMG utilization.