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Taxonomy and description Description New rail services on existing lines can provide either new opportunities for people to travel or to improve upon existing opportunities to travel by providing a more direct services and so reducing the generalised cost of travel. In the UK examples of the latter include Hull Trains direct Hull to London service, whilst examples of the former tend to be based around services to and from new rail stations [put in hyper link] that have been opened on existing lines. New rail lines offer new opportunities for people to travel and, hence, increase the geographical accessibility of the rail network. By default new rail lines will contain new stations. The large capital costs of new rail lines mean that by and large they tend towards small scale extensions of existing lines to major traffic generators (e.g. Manchester Airport ), although occasionally they can be a lot more substantial, e.g. Heathrow Express line and the Argyle Line in Glasgow. Upgraded rail lines can involve the electrification of current track, the alteration of its alignment, constructing passing loops or increasing capacity in certain areas. The main reasons to upgrade tend to be to enable faster trains to operate on an existing rail line, to increase the capacity of the current rail line and to improve the reliability of current train services on the existing rail line.
There are a number of other service level changes which have been identified by TRB (2003 author) and TRL (2004). These include: 1. Regular Interval & Clockface Timetables – The former involves
the implementation of a timetable that schedules services to arrive at
a station or bus stop, at regular intervals, e.g. every 20 mins. The latter
schedules services to arrive at the station or bus stop at the same time
past the hour, e.g. 10 minutes past and 30 minutes past the hour. The
reasoning behind these service patterns is that they should be easy to
remember and will, in some cases, help minimise transfer times (Shires
et al, 2003). They are very prevalent in Switzerland, the Netherlands,
Austria and Germany. Terminology A change in service frequency will impact upon passenger demand in a number of ways, however in terms of terminology there are three which perhaps need to be clarified and result from a change in service frequency. Schedule Delay Time – This is the difference between when a passenger would most like to travel and the actual time of travel. This could involve the time spent waiting at home or at work before walking to the bus stop. The estimation of schedule delay time depends upon when passengers would ideally like to travel, the timetable and passengers’ preferences for arriving early or late. As service headway (time between two particular buses normally calculated as 60mins/number of buses per hour) increases it is likely that this element of generalised cost (the monetary and time cost of a journey) is of greater importance than scheduled wait time. Schedule Wait Time – This is the time spent waiting at the stop and is usually taken to be a function of the service headway and service reliability. Where services are frequent and at regular intervals, passengers are assumed to arrive at the bus stop at random and are therefore assumed to wait on average a time equal to half the service headway. Where services are infrequent, it is assumed that passengers time their arrival at the bus stop to coincide with the arrival of the bus. Excess Wait Time – This is additional time spent at a bus stop/station when the passenger has been unable to board the first bus due to overcrowding. This component is largely beyond the control of the passenger and is a function of demand and the capacity of the service. Without knowing more about the desired departure times of passengers it is difficult to accurately estimate schedule delay time and excess wait time and for this reason it is common to find scheduled wait time as the sole representative of service frequency in the specification of generalised cost, e.g. half of the headway = (30 mins/number of buses per hour). Technology It is much easier for bus services to implement changes to their current service levels on a daily, weekly or monthly basis, than for other more technical public transport systems such as rail and air which have to wait several months. Both rail and air operate on or from highly specialised infrastructure, where safety procedures are strictly adhered to. As such there is a high level of interaction between all services that mean changes to one service have considerable knock on effects to the network as a whole. For these reasons any changes in service levels have to be co-ordinated at a network level following discussions with all affected service operators. As such changes to service levels can take several months to be approved and implemented.
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