Anita Schöbel

Learn More
Dealing with delayed vehicles is a necessary issue in the dispositive work of a public transportation company. If a vehicle arrives at some station with a delay, it has to be decided if the connecting vehicles should wait for changing passengers or if they should depart in time. A possible objective function is to minimize the sum of all delays over all(More)
An important strategic element in the planning process of public transportation is the development of a line concept, i.e. to find a set of paths for operating lines on them. So far, most of the models in the literature aim to minimize the costs or to maximize the number of direct travelers. In this paper we present a new approach minimizing the travel(More)
In this paper we consider set covering problems with a coefficient matrix almost having the consecutive ones property, i.e., in many rows of the coefficient matrix, the ones appear consecutively. If this property holds for all rows it is well known that the set covering problem can be solved efficiently. For our case of almost consecutive ones we present a(More)
Given a railway network together with information on the population and their use of the railway infrastructure, we are considering the e ects of introducing new train stops in the existing railway network. One e ect concerns the accessibility of the railway infrastructure to the population, measured in how far people live from their nearest train stop. The(More)
We consider a geometric set covering problem. In its original form it consists of adding stations to an existing geometric transportation network so that each of a given set of settlements is not too far from a station. The problem is known to be NP-hard in general. However, special cases with certain properties have been shown to be efficiently solvable in(More)