Dimensioning of a railway station for unknown operation

Every now and then new railway stations are brought into operation on existing lines. This is a good way of increasing the availability of railway services and attracting more passengers. However, from a capacity point of view, this procedure can be quite tricky, since new stations and additional stops thoroughly alter the traffic properties of the line. The addition of a station like this in Solna, north of Stockholm is under discussion. Here, most of the regional trains, but probably not the long-distance trains, would stop for passenger exchange. A new line, connected to the main line just north of Solna, would also contribute to the traffic flow through the new regional station. The essential question in this project was to determine the number of platform tracks needed to cope with the traffic flow. However, it has proven difficult to find a representative timetable structure to use in the dimensioning work, both the total number of trains and the distribution between stopping and passing trains turned out to be uncertain. A combinatorial method was therefore applied. Using this approach, a large number of timetables, i.e. possible traffic situations, were generated and tested (automatically) for the number of platform tracks needed. Constructing and using this simple model forced the engineers to understand and describe the fundamentals of this operational/scheduling/dimensioning problem. The procedure hence gave useful insights about the system properties and a direct knowledge of the sensitivity of different factors that are essential for the number of tracks needed at a railway station like this.