Berechnung und Bewertung der Gesamtleistungsfähigkeit von Eisenbahnnetzen

摘要

Calculation and assessment of overall capacity in railway networkOne of the main objectives of railway operation research is the assessment and evalua-tion of railway capacity. In this context, capacity denotes the possible number of train runs, which can be operated on the infrastructure compliant to a predefined level of ser-vice.In view of the forecasted increase of rail traffic in Europe the optimal use of the existing infrastructure is becoming increasingly important. In this regard, the analysis of the re-sidual capacity of railway stations and lines, respectively, is an essential prerequisite to assess the feasibility of additional traffic volume in the network. In medium- and long-term planning of infrastructure and operations analytical queueing-based approaches have been widely used to determine the capacity. Besides being ap-plicable to existing timetables these methods are particularly suited to cope with uncer-tain input, e.g. if only a rough operational concept, but no precise timetable exists. Ac-cording to the state of the art in this sector, the railway network is generally decomposed into smaller infrastructure elements such as lines, set of tracks and route nodes. In terms of capacity, these elements are investigated individually, whereas interdependencies between different elements and the capacity of the entire network cannot be assessed, globally. However, it is precisely the overall capacity, and not the individual results for lines and nodes, which are of particular interest for infrastructure and timetable planning.The goal of this thesis is to provide an approach enabling the optimal utilization of the available capacity in railway networks. By taking a network perspective on capacity in-cluding alternative train routings the developed method allows for a detailed description and capacity evaluation of infrastructure modifications. Apart from the identification and prevention of system bottlenecks in infrastructure planning it also provides valuable in-sights in timetable design facilitating a demand oriented design of operations. At this point, the approach is not limited to the construction of new timetables from scratch, but can also be used to optimally attribute residual capacities to additional train runs in exist-ing timetables. In the present work, the calculation and assessment of overall capacity in railway net-works is performed using a macroscopic model based on railway lines, set of tracks and route nodes. The capacity allocation for train courses is based on a two-stage model. The first step consists of finding all economically feasible train paths for the demanded relations by solving a shortest-path problem. In the second process step, infrastructure capacity is assigned to individual trains using a mixed-integer programming approach. The objective of the routing problem is to maximize the number of feasible train runs through the network. The capacity is determined based on a train specific extrapolation of the existing operating program on each infrastructure section.To determine the individual capacities of lines, set of tracks and route nodes, which pro-vide constraints to the routing MIP commonly used analytical procedures in railway ca-pacity analysis are used. Currently, these procedures rely on differing modeling tech-niques and input data requirements. Capacity analysis of railway stations, for example, usually relies on so-called scheduled waiting times, which originate in timetabling when trains need to be shifted from their original timeslots due to conflicts with other train runs. The assessment of railway lines, by contrast, is performed based on knock-on delays, which arise in operations due to conflicts between trains arising from perturbations or initial delays in the planned timetable. In order to ensure the comparability of the calcula-tion of the capacities for the different infrastructure elements, a methodology for the standardization of the different approaches is developed. For example, the applicability of the Strele-formula – which has previously been used to model railway lines – has been extended to route nodes by incorporating a parameter concatenating different train moves. For the first time, the calculation of capacity for railway lines and railway nodes can now be carried out based on the same database.The presented approach has been validated based on prototypical calculations for a realistic subnetwork of the size of North Rhine-Westphalia. The network consists of 51 set of tracks, 102 route nodes and 150 railway lines. It has been shown that, by optimally assigning residual network capacity based on the developed method, the number of train runs on this network can be increased by up to 18%. The methodology hence provides a significant improvement in network and timetable planning.