Tailored timetabling at SBB

The Swiss are world champions of rail travel. Every day, approximately 10,000 trains travel on Switzerland’s standard-gauge network which covers just over 3,665km. They take almost a million people to their destinations – safely and punctually – and transport 200,000 tonnes of freight. These impressive figures are unequalled anywhere else in the world. To cope with the constant rising demand on this heavily used network, SBB Infrastructure applies an ingenious timetable planning process.

At the core of the process is the ‘planning pentagon’ (see Figure 1). The demand forecast determines the product offering, which in turn forms the basis for the timetable. The latter defines the functional requirements to be met by infrastructure and stations as well as by the rolling stock. And finally, the financial arrangements determine the implementation timeframe.

In other words, construction only goes ahead insofar as it is needed to implement the new, to-the-minute timetable. The network is tailored to the timetable so that usage becomes more and more efficient.

Given Switzerland’s limited size, the emphasis is not on speed but on meeting enormous demand; and at the same time financial, ecological and spatial-planning aspects must be taken into account. To cater for increased demand on a section of route whose capacity is already fully utilised, a number of possibilities exist in principle – for example: to deploy longer trains with more seats (double-deck units); to shorten train headways; to harmonise speeds of freight, regional and long-distance trains; and to build additional tracks and segregate traffic flows (with flyovers, etc.).

Planning process

Long-term planning (approximately 8-20 years prior to implementation)

Demand for travel is rising. The federal parlia – ment and the cantons decide which services are to be expanded and where. SBB Infrastructure is tasked with conducting studies for developing a basic regular-interval timetable that will enable the desired service offering to be implemented. Despite the long planning horizon, once the capacity requirements have undergone structural analysis, this development work is already performed down to an accuracy of one minute. As a rule, different timetable concepts for the future always point to the same bottlenecks in the network. The upgrade/expansion work ultimately implemented is geared to the concept that achieves the greatest consensus among the stakeholders involved (parliament, cantons and railway undertakings).

If the planned service offering cannot be implemented with the infrastructure and rolling stock available, the necessary infrastructure upgrades and/or rolling stock specifications are defined in a series of detailed agreements between the Federal Office of Transport (FOT), the cantons, the railway undertakings (RU) and SBB Infrastructure. The ultimate goal is to always find the solution with the best cost-benefit ratio. Timetable and train-operation simulations assist in the definition of these tailored investments.

A legislative ‘message’ is submitted to the federal parliament setting out the necessary financing concepts. This iterative step outlines the future timetable concept and the way in which the necessary rail network is to be financed. Under certain circumstances, the final decision is taken by the Swiss electorate in a referendum.

An overview of the measures planned in Switzerland for the period up to 2025 can be viewed on the Federal Office of Transport’s website1.

Medium-term planning (approximately 2-8 years prior to implementation)

In this phase, the timetables are planned in detailed, taking due account of the necessary construction phases for the expansion/ upgrade works. In addition, time windows are created and integrated into the timetable for maintenance and renewal work on the existing infrastructure.

Individual additional trains (especially those designed to strengthen services at peak travel periods) are worked into the timetable alongside the basic diagrams. Talks then begin with neighbouring countries’ railways on the planning of international connections.

Deployment of rolling stock is defined and deadlines are set for the commissioning of new installations.

Narrow-gauge lines plus bus and boat companies are informed about the future services so that the entire public transport chain can be properly coordinated. In this phase, an important role in coordinating the overall service offering is played not only by the transport companies but also by the cantonal offices for public transport, which commission the services.

Annual planning (two years prior to implementation and up to the timetable change)

Two years before implementation, the timetable planners start planning the precise 24-hour annual timetable. The times of the first and last trains to adopt the basic regularinterval timetable are defined, along with detailed amendments (including extra stops, for example) at off-peak times. A train-path catalogue is set-up for freight services.

Actual ordering of RUs’ train paths can then begin. If RUs request short-term changes, it is possible prior to the ordering process to check the feasibility of such changes and integrate them into the timetabling process. To ensure that all RUs are given non-discriminatory access to the rail network, they submit their train-path wishes to the independent path-issuing body – Trasse Schweiz AG (Swiss Train Paths Ltd). Provided they are feasible, the paths can be provisionally allocated. The RU then has the opportunity to ascertain which train paths it wishes to order on a definitive basis. It has to do this by arrangement with its customers. In the freight segment these may, for example, be container shippers, whereas for regional passenger services the cantons (in conjunction with the FOT) comm ission the timetable offering. If two RUs request the same train path and no alternative can be offered, Trasse Schweiz AG decides on the awarding of the requested path. The timetable is then published in the online and official printed timetables and handed over to SBB’s operating units.

Creating the daily timetable (after timetable changeover date)

During the course of the year, the remaining gaps in the timetable are filled with additional trains for events (e.g. exhibitions and concerts), relief trains (where heavy traffic is predicted at weekends or at the beginning or end of holidays), charter trains, seasonal freight traffic, one-off consignments or service trains (for engineering works or trade fairs).

Analysing the timetable

The current timetable is subject to ongoing analysis. In this process, the main focus is on punctuality. Every opportunity for improvement is identified and – unless it can be implemented immediately – incorporated in the next timetable.

Basic principles of timetable planning

Symmetrical regular-interval timetable

In Switzerland, timetables are organised symmetrically around the hour (‘minute .00’). If a train arrives at ‘x’ minutes before the hour, its counterpart travelling in the opposite direction departs at ‘x’ minutes after the hour. This basic timetable structure is then repeated every 60 or even every 30 minutes. In other words, it follows a ‘clockface’ rhythm.

As connections to other services are always the same in both directions, passengers can thus work out the departure time of their return service themselves.

Node concept

A node station is a station at which a rapid succ – ession of trains arrive from different directions, thus permitting close connections, and subsequently depart again at around the same time. Owing to the symmetry provided, this is best achieved on the hour (.00) or the half hour (.30). With half-hourly services, which are becoming increasingly common, additional transfer possibilities are created at 15 and 45 minutes past the hour. To permit the greatest possible number of suitable nodes, the travel time between the individual nodes must be kept within half an hour or one hour, as the case may be.

This node concept, which is highly developed in Switzerland, defines the underlying principle – namely, that trains should travel not simply as fast as possible but rather as fast as necessary to ensure good connections at the next node. This not only greatly reduces costs but also generates the greatest possible benefit for the public transport network throughout Switzerland.

Timetable design

Timetables are planned in accordance with the regulatory specifications of the FOT. The timetable planners thus adhere to a certain hierarchy. First, long-distance passenger and transit freight trains are scheduled. Next, interregional passenger services are timetabled along with domestic freight trains. And finally, regional services – i.e. S-Bahn rapid transit and short-distance freight services – are integrated into the timetable.

IT systems

The operating framework for a timetable is so complex that it has not yet been possible to automatically generate timetables for a network the size of the Swiss standard-gauge network. This remains a manual task performed by timetable planners and requires a great deal of experience and detailed knowledge. However, the planners have powerful tools at their disposal for visualising the timetable in various ways (i.e. network and route diagrams and track occupancy plans). For medium and long-term planning they utilise the Viriato programme, while for annual and daily scheduling the NeTS (‘network-wide train-path system’) is used.

At the microscopic level, future timetables can be simulated using the Open Track2 tool. This already comes into play in long- and mediumterm planning by optimally defining the required infrastructure and helping to identify and address stability risks in future timetables. In this process, various delay scenarios and disruptions are simulated in order to estimate their impact.

The OnTime3 tool is used to calculate the expected punctuality of a future timetable. This tool allows us to compare different time – tabling options, to identify their weak points, and to address these proactively.

The data on trains that have already operated are analysed intensively to enhance timetable quality. For this, we use ‘Open Time Table4’ – a tool which very efficiently examines the quality of the timetable that has been produced. This process is assisted by statistical analyses of the ‘train’, ‘time’ and ‘place’ dimensions. The findings obtained flow directly into the planning process for the next timetable, thus ensuring continual improvements.

References

1. http://www.bav.admin.ch/themen/03044/ index.html (Ger/Fr/Ital only). 2. http://www.opentrack.ch/ 3. http://www.ontime-rail.com/index_en.html 4. http://www.via-con.de/en/development/ open-timetable-ott

Biography

Dr. Helga Labermeier studied her Ph.D. at the Swiss Federal Institute of Technology in Zurich in Operations Research. After – wards she spent four years in the Strategic Network Planning Department at Swissair as an expert of the demand and market model. At Swiss Federal Railways, Helga’s functions have been – besides others – in the field of business analysis and requirement management of the new dispatching system (RCS) and the development of the new Customer Punctuality KPIs. Today Helga works as a Scientific Specialist in the team for methods and simulations in the Timetable Planning Department.