Bottlenecks in railway networks are in most cases characterised by technical capacity measures. The theoretical capacity is defined to be the maximal number of trains which can be operated on a railway link. This measure is dependent on a number of factors such as the type of trains, the speeds, and the mix of trains as well as the operation and scheduling systems. Theoretical models based on queuing theory are available but cannot be implemented on the European scale yet. Therefore simple pragmatic rules are chosen to define the practical capacity, which denotes the maximal number of trains on a link which can be operated without unacceptable delays. This measure can be calibrated using the experiences of experiences of national railway companies or the UIC. In this paper the technical capacity is shown as a not sufficient measure to identify the major deficiencies in railway networks. Much more important than technical bottlenecks are insufficient levels of service of the railways. This is the main reason why the companies are not able to compete successfully on the markets for passenger and freight transport. Thus this paper emphasises so called level-of-service (LOS) bottlenecks. Indicators for LOS bottlenecks are derived from a European railway network model which includes the UIC database. A link oriented bottom-up and an OD oriented top-down approach are presented. All indicators defined are quantified using the established European railway network model. It turns out that the situation of the railways looks much worse if LOS indicators are used instead of technical capacity measures. Environmental effects can create bottlenecks which may have negative as well as positive impacts on the railways. (A)
Samenvatting