For passengers, the following factors are considered to be the most important in determining the mode used to access the airport:
Convenience, including convenient terminating points at both ends of the journey;
Availability and relative attractiveness of the mode including issues such as safety and privacy;
Cost, although this is regarded to be a secondary concern to passengers by de Neufville and Odoni (2003);
Reliability of transport;
Comfort and quality of transport;
Distribution and distance of passenger origins and destinations. (Humphreys, 1996, Ashford et al., 1997, Kazda and Caves, 2000, de Neufville and Odoni, 2003)
Speed is not regarded as a primary concern for passengers, particularly if they have to wait for a long time once at the airport, although the frequency and reliability of the access mode should be high. (Bonnet, 1980)
While the six factors listed above relate directly to passenger they are also relevant to other groups of surface access users although accompanying persons, employees and visitors will each rank the factors differently in terms of importance (Kazda and Caves, 2000). The choice of surface access mode is not so relevant to suppliers to the airport who will predominantly use cars, vans and lorries.
Caves and Gosling (1999) consider that improvements in access may also be determined by airport size. For medium sized airports, improvements will normally be in the form of contributing towards the costs of improvements in the local road network, while larger airports should aim for a progressive shift towards public transport.
Table 2.4 details the modal split of passengers and employees at selected UK airports. The data suggest that the private car is the preferred mode of travel for both employees and passengers. At the smaller and medium sized airports such as Bristol, Nottingham East Midlands and Norwich, the percentage of trips made by public transport modes is below five percent, a key reason for this being the lack of public transport alternatives available (Humphreys and Ison, 2005).
Table 2.4: UK Airport Surface Access by Public Transport for Passengers and Employees
Source: Humphreys and Ison, 2005
2.3.1 Modal Choice of Employees as Surface Access Users
From the employee perspective, the private car is the most convenient and flexible mode of access to an airport. Higher modal splits in favour of the private car have been found for employees than for air passengers. The main reason for this is because all employees start and finish their trips from their place of residence (Humphreys, 1996, Ashford et al., 1997).
Research conducted at Paris airport cited three reasons why 80 percent of employees used private cars for their access journey. The reasons were:
Most employees live in the suburbs where there is a lack of public transport links to the airport;
The dispersal of work locations on the airport site is often not closely related to the public transport terminus, making the mode inadequate for many employees;
Public transport does not serve many employees whose shift times fall outside the
hours of public transport operation. (Bonnet, 1980)
While now a little dated, the small amount of more up to date research may suggest that the reasons still hold true. Such findings are, however, mirrored by more recent research by Humphreys and Ison (2005) who state that a complex situation exists in terms of changing employee parking behaviour because of dispersed origins and destinations, shift patterns which are incompatible with public transport timetables and the fact that at some airports as few as seven percent of employees may work for the airport company itself, thus making it difficult for the airport to persuade workers of tenant companies to change their travel behaviour.
As long as such circumstances exist, there is unlikely to be any significant reduction in the use of the private car by employees. The research by Bonnet (1980), however, only focuses on public transport as an alternative to the private car. It does not consider measures which may encourage a more efficient use of the car, such as car sharing, or initiatives such as home-working and teleworking. The idea of staggering work schedules is briefly mentioned but without much foundation. While altering work schedules may have the impact of relieving some road congestion it may also reduce the number of employees who make use of public transport, thus generating more road based traffic at other times.
Price is considered to be a more important factor for employees than passengers as they make round trips every day (Bonnet, 1980) although de Neufville and Odoni (2003) state that price considerations tilt both passengers and employees to use the private car to access the airport. This comment would, however, appear to some extent to contradict a statement by the authors that cost is generally a secondary concern for passengers.
Considering other modes of access, Humphreys (1996) discusses the use of demand responsive transport, where buses vary their routes to accommodate passengers who request to use the service. Such a scheme could be adopted by employers who could either provide
“in-house” demand responsive transport for their employees or promote existing schemes.
This is similar to the concept of car sharing. Ashford et al (1997, p.427) state “Rail links seldom attract large percentages of airport employees. Because of the size of airports, employees’ destinations on the airport can be a long way from the passenger terminal; also employees will not necessarily select a residential location that gives a good public transport link to the airport.” The effectiveness of rail will be dependent on the size of the network
and on the location of stations at either end of the journey. National rail is likely to be unsuitable for employees but local and regional rail networks, such as the London Underground at Heathrow or the Tyne and Wear Metro at Newcastle International Airport in the UK may be more suitable for employees as they serve a wider area including the suburbs and they link into other transport networks well. The attractiveness of rail timetables and their relationship to shift patterns can also make them a viable or unviable option. Similar arguments can be applied to buses. Their usage by employees will be largely dependent on the location of the bus terminal at the airport and the coverage of the network.