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Public transport services
Taxonomy and description Description Public Transport Services refers to the entire range of transport services that are available to the public. This can include demand responsive transport, bus, trams, light rail systems, metro (underground) and long distance rail services. This note considers the service levels and quality aspects of public transport. The frequency of public transport services and the hours they operate are the key components that need to be considered when discussing changes to public transport service levels. The former may be described as the number of buses per hour and can often vary between the peak and non-peak periods of operation during the mid-week (Monday to Friday), evenings and weekends. The latter corresponds to when services start and finish. Again this may vary between weekend and non-weekend periods. Service coverage is an important issue, that is to say the degree of network coverage over a given area (the density and extent of the network). If services are concentrated along main corridors then the network coverage is likely to be poor and result in lower levels of accessibility for passengers than when services have a greater spread. The trade-off between both approaches is the level of service frequency each can offer. By concentrating services along key routes bus operators are able to maintain a much higher frequency of services compared with a network that offers greater levels of coverage. A broad definition of quality is the “totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs” (ISO, 2000). In relation to transport, Metz (2005) has stated that the “quality of a journey is a function of comfort, reliability, safety, and security”. Therefore service levels are also seen as a factor in determining the quality of public transport services as they influence reliability. An increase in service levels can improve the quality of public transport as the service would have increased reliability and become more readily available. Karu et al (2007) consider quality aspects in their public transport quality evaluation to be public transport reliability, security, frequency, times of operation, schedule and routes, public transport cost as well as the preference of car usage or walking. This also considers service levels more directly. Because time spent travelling within the public transport vehicle is only a proportion of the total journey experience faced by the passenger, it is necessary to individually analyse the various component elements of the entire journey made by public transport. Kelly (1996) attempts to do so as follows:
Various instruments can be employed to improve the quality of public transport. It is not intended to list all instruments here but to give a flavour of how the quality of the entire package of public transport can be improved using this framework of analysis as shown in Table 1. Table 1: Examples of Instruments that can be used to improve the journey experience
The above is a simple framework, with cases where an interchange is involved, this will increase the need for the “walk”, “wait” and “ride” elements. Kittelson & Associates et al (2003) provides some of these questions under several broad categories as follows: Availability
Capacity availability: Is passenger space available for the desired trip? Comfort and Convenience
Service Delivery
Safety and Security This relates to the likelihood or more importantly perceived likelihood that one will be involved in an accident (safety) or become the victim of a crime (security) while using public transport. An example question in this category:
Maintenance Are the vehicles and facilities clean? “The quality of a transit agency’s maintenance program has direct and indirect impacts on passengers’ perceptions of service quality.” It is clear from this framework that while attempts have typically focused on adjusting fares to compete with the private car, it is in fact the quality of the public transport trip that plays the crucial role in determining the entire decision process whether to use public transport for a particular journey in the minds of the user. The UK government allows local authorities, county councils, unitary authorities and Passenger Transport Authorities to draw up a scheme for improving bus services known as a ‘Quality Bus Partnership’ in its local bus strategy. DfT state: “A QP scheme in effect represents a commitment on the part of the authority to provide certain facilities to improve local bus services, and to maintain them throughout the life of the scheme; and an obligation on the part of participating bus operators to meet the quality standards prescribed in the scheme when using the facilities in question”. A Quality Bus Partnership aims to consider the service dimensions: journey time and reliability (determined by labour/equipment availability, congestion levels and infrastructure priorities), information (determined by stability/knowledge, printed/interactive information), comfort (determined by vehicle quality, driver quality, traffic environment), and access to the system (determined by low floor buses, sops and interchanges). Other Types of Service Level Changes There are a number of other service level changes which have been identified by TRB (2003 author) and TRL (2004). These include:
Why consider Quality in Public Transport Services?When we consider public transport, except for particular specialised services and first class services on rail networks, passengers do not generally have the option of purchasing an additional quality element. The practice thus far in public transportation planning and management is that conventional planning tends to overlook service quality impacts (Litman, 2008). In particular quality factors are generally not analysed to any large extent in considering public transport costs even if some of them have been valued in monetary terms using techniques such as stated preference modelling to elicit choices of a sample of the population under hypothetical scenarios (Balcombe et al 2004). Enhancing the quality of public transport broadly targets two groups of public transport users:
These terms represent polar ends and it should be emphasised that the “captive market” should not be thought of as a market that will always use public transport. Hence authorities and operators should not be complacent that they will always be there. This market is not static. It will more often than not shrink with changing socio-economic demographics, rising income levels etc. Experience indicates that these “captive” customers will in due course find alternatives. These “captive customers” are not to be thought as the equivalent of loyal customers. That loyalty can be gained through delivery of a service that meets the user’s satisfaction. With regards to the choice market, the public transport provision has to be competitive against the private car in meeting travelling needs of the user. As an example given in Litman (2008), car owners have the option and are often willing to pay considerable sums to include a variety of “optional extras” such as satellite navigation systems, leather interiors in the car. Whilst the basic need of the car owner is a means of provision of transportation from point A to point B, the quality elements and more importantly the image associated with ownership and use of this car is clearly an element of importance in the decision making process of car ownership and purchase. If more car users are to be persuaded to choose the option of public transport instead, the entire package of public transport options available has to be improved considerably. When approaching this group, the objective of quality is designed to entice these choice users by ensuring that public transport caters both to their basic transportation needs and also to their implied needs. For them, public transport needs to deliver at least a journey experience rivalling that, or better than, the private car. Hence measures improving the image of public transport, enhancing safety and personal security, reducing overcrowding are targeted at this segment of the market. Terminology A change in service frequency will impact upon passenger demand in a number of ways and will have an impact on the quality of public transport provided. However in terms of terminology there are three which perhaps need to be clarified and result from a change in service frequency and impact greatly on the quality element of reliability. Schedule Delay Time - This is the difference between when a passenger would most like to travel and the scheduled 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) increases in importance relative to 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 the demand compared to capacity of the service. Technology It is technically relatively simple for bus services to implement changes to their current service levels on a daily, weekly or monthly basis although timetables will need to be altered accordingly. A simple light rail network may also be relatively simple technically to amend service levels. Heavy rail systems with complex networks are far more difficult to amend. Heavy rail operates from highly specialised infrastructure, where safety procedures are strictly adhered to. As such there is a high level of careful co-ordination 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 and if there are several operators then they must involve 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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