Physikalische Maßstäbe zur Beurteilung des Leistungsverhaltens von Eisenbahnstrecken

The assessment of the load of a railway line and the determination of the optimal number of trains (called “practical capacity”) require a valuation function which limits the load-dependant waiting times of trains. If a line section is considered, waiting times arise before trains enter the section and also along their course through the section, including stations and junctions along the way. Waiting times may be delays (operational) or scheduled. Existing attempts to measure operational quality on railway lines as an effect of the level of waiting times have relied on the subjective assessment of quality by operation professionals; more recently, economic approaches have been tried. In principle, productivity or profit parameters can be used for the microeconomic assessment. However, results can often be estimated only roughly and with difficulties due to the poor general availability of business data. Therefore, a new approach is taken in this thesis: the development of an easily applicable valuation function using parameters derived from physics (“physical parameters”) that are based on economic ones. The first way of developing the new valuation functions consists of testing the basic physical parameters towards their appropriateness for modelling the operation of railway lines in terms of quality and quantity. Through adequate combination of the appropriate basic parameters the physical parameters for the new valuation functions are derived. The second way starts with identifying the parameters that influence costs and revenues and assessing their relevance. Physical parameters are then used to describe the functional form of those economic parameters. The investigation shows that the costs mainly depend on the length of the line and the transport time. The transport time includes the scheduled transport time as well as operational waiting times (delays), which depend on the load of the line. In order to take account for the fact that different train types have different relevance for the total cost, the transport time of a train category is weighted by the sum of the masses of all trains of this category per time unit. The derived physical quantity is the weighted sum of transport times. The revenues mainly depend on the transport length, the transport volume and the reaction of transport demand relative to a base scenario. The transport volume is modelled by the train mass, and the changes in demand are represented by the reciprocal value of the transport time. The physical parameter for the revenues is therefore the product of mass and velocity, which is a momentum. While the weighting factors for each train category are taken into account, the momentums of all trains are added up. The resulting quantity is called transport momentum. Central parameters of the economic assessment of the load of a railway line are the profit and the productivity. The physical parameter describing the productivity is the quotient of the transport momentum and the weighted sum of transport times, called transport force. The physical parameter for modelling the profit is the difference between the physical quantities of revenues and costs and is called transport momentum difference. In order to validate the new approach, the functional form of each physical quantity was compared with the functional form of the corresponding economic quantity. Both the convergence at the limits of the domain and the shape of the curves in between were examined. Finally, the new approach was applied to several examples. The examples show that the new approach leads to values for the practical capacity which are slightly higher than those obtained by existing models, which tend to underestimate optimal train volumes. The new valuation algorithm is therefore suitable for assessing the impacts that changes in the infrastructure and of scheduled train programmes exert on capacity.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Oetting, Antje

Contributors dc:contributor

• Schwanhäußer, Wulf

• info:eu-repo/classification/ddc/620
• Ingenieurwissenschaften
• Bewertung Angebotsqualität
• physikalische Maßstäbe
• Nennleistung
• Kapazität
• capacity
• practical capacity

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123143%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:61482