Designing a Better Timetable for Britain's Railway
J Tyler, Passenger Transport Networks, UK
The timetable is the essence of the service offered by a public transport operator.
Unless a train or bus, a plane or ferry is available at times reasonably close to when a potential customer wishes to travel the offer will be unattractive, and those who have an alternative ? typically the private car ? will use it. Other features of the service, such as price, facilities and ambience, do of course influence decisions, but the timetable is the sine qua non. Yet, as this Paper will argue, it has in Britain been neglected, in terms of institutional arrangements, managerial attention and research. The probable price of such neglect is sub-optimal use of the rail and bus networks to a degree that may have profound implications for public policy, modal split and the environment.
The author is managing a Project entitled Measuring demand for an integrated inter-urban public transport network under the Future Integrated Transport Programme of the Engineering and Physical Sciences Research Council [EPSRC] and the Department for Transport [DfT]. The partners are the Institute for Transport Studies in the University of Leeds [ITS], the author?s consultancy ? Passenger Transport Networks [PTN], Network Rail, the Association of Train Operating Companies [ATOC], Eden Business Analysis and SMA of Zürich, with the Strategic Rail Authority [SRA] as an observer. Funding is provided by EPSRC, DfT and ATOC, and the industry is enabling access to all necessary data. SMA has contributed its Viriato timetabling software, as used by the Swiss, German and other mainland Railways.
The Paper will describe the Project, report its findings and discuss their implications. It was a cardinal tenet in its conception that the research would not be restricted by history, organisations, prevailing legal arrangements, conventional operating practice and existing service patterns. This is not to say that any of these are necessarily irrelevant or wrongly constituted, but rather that a clearer view of what is best for individual travellers and, perhaps of greater importance, what is best for the community collectively, will be obtained if the researchers can construct an ?ideal? network of public transport from first principles. This was felt to be particularly timely because, in addition to it not having been attempted previously in Britain, it was evident that decisions regarding the strategic direction of the railways were rapidly rising up the political agenda. If the conclusion is indeed that managing the system differently could yield significant benefits there will be cause to consider the institutional, financial, operational and transitional requirements.
The first task was to design a network that reflects the distribution of population and economic activity. Given its history of incremental change it cannot be assumed that the railway system, either in its infrastructural form or in its pattern of services, is entirely appropriate for present and future needs. Other industries and services have developed tools to review their activities comprehensively, and although restructuring a railway is subject to greater physical and socio-political constraints than, say, opening and closing branch shops, it cannot be the case when substantial reinvestment is under way that the railway should not be subjected to a radical appraisal of its fitness for purpose.
The outcome of three analytical methods to select the nodes of a comparator network will be discussed: identification of the hierarchy of urban places as the foci of economic and social activity; systematic aggregation of small units of population (?nodules?) into larger units (?nodes?); and simulated annealing. Urban hierarchies are well understood in the geographic literature but do not appear to have been deployed in this planning context, nor has the effect of hierarchic relationships on travel demand been evaluated.
Data from various sources is yielding a new hierarchy for the whole of Britain, including suburban centres. Aggregation is based on the Royal Mail database that records the number of households and businesses comprised in each unit Postcode. Programs have been written to merge these units progressively on the basis of proximity and/or size, at a first level into units corresponding broadly to the population or area served by a bus stop and at a second level to that which might be served by a railway station. Annealing is an established methodology for finding optimal locations, and it has been adapted here to work with the Royal Mail data in a manner that complements the aggregation technique.
Conventional algorithms then connect the set of nodes with the most efficient (as may be defined) arrangement of links. All network design must balance the cost of its total length against the impact of deviation from a straight line, but this is particularly important for railways, for example in respect of the imperative to reach threshold volumes of traffic. The indications are that these analyses, while delineating a recognisable national network (it would be troubling if they did not), will highlight some significant departures from the ideal in the current layout. These include the considerable variation in the quality of services connecting the high-order centres that account for a large proportion of the population, of economic activity and hence of travel; the mediocre access to longer-distance services offered to many suburban centres; and the limited relevance of railways for small towns and rural areas (good connecting bus links are another matter and form a sub-theme of the research).
The second task is to design an entirely new timetable based on these findings. The weaknesses in the existing timetable are not however limited to the consequences of slow incremental evolution in a changing geographic context. Over many years they have included a chronic failure to construe the system as a network (experienced by travellers as poor connections between services), arguable operational practices and inattention to vital details of the timetable as the catalogue of what is on offer. Matters have been made worse by the creation of a mystique around timetabling that has obscured both the technical and the inherent policy issues and made compilation seem more complicated than it need be. And the division of responsibility between the network operator and multiple train companies (circumstances unique in Europe) has added the problems of poor coordination and apparent overuse of capacity.
A fundamental review of principles is therefore opportune. Many would argue that against the instant convenience of the private car the only timetable capable of influencing behaviour in the long run is one in which services operate on a repeating pattern throughout the day and every day, with a strong emphasis on the connectivity of the network by means of tightly-ordered interchange at junctions. This approach is commonplace in mainland Europe, notably in the Swiss Taktfahrplan, the longstanding scheme in The Netherlands and the new timetable in Germany, but it has only been adopted piecemeal in Britain. Some train companies are convinced of its merits, but others maintain that it does not adequately cater for customers? needs or insist on asserting access rights.
The redesign will establish what a British Taktfahrplan might look like if the clear logic that underpins Swiss planning were applied. Most importantly, the timetabling is a real process using the Viriato software and railway data and rules, not an academic exercise or an interest group?s wish-list. Case-study results will be tested against the current service offer and the industry?s own plans in order to measure the likely public response, the revenue benefits and the cost implications, including the priorities that would be set for infrastructure improvements. Two methods will be used, the existing industry standard model for the sake of compatibility and a new demand model that incorporates directly the access and egress stages of a journey. The latter is complemented by a stated-preference study of perceptions of timetables and by an attempt to measure their characteristics in such a way that the effect, if any, of different service structures can be calibrated.
The Project started in 2001 and will report in the summer of 2003. It should be stressed that only at that stage will the industry partners take a view on the findings. Although this Paper therefore represents a technical report on possibilities it will contribute to the debate on the SRA?s Capacity Utilisation Policy, whose practical effects will by then be being felt. It may also be relevant to the wider European debate on capacity allocation legislation and procedures.
Association for European Transport