2.2.1 The Airport Population and Surface Access Users
Four categories of people who use the airport surface access system can be seen to exist, each of which has its own specific characteristics. They are:
Originating and terminating passengers;
Employees;
Supply, delivery and other commercial vehicles, and;
• Visitors to the airport. Transit and transfer passengers also exist and form part of the
“airport population” but do not use the access system as they arrive at and depart the airport by air. (Humphreys, 1996, Ashford et al, 1997, Kazda and Caves, 2000, de Neufville and Odoni, 2003)
Kazda and Caves (2000) state that at medium and large airports, the number of employees who commute to the airport represents between one quarter and one half of the daily number of airline passengers. They add that visitors to the airport, also referred to as “accompanying persons” or “meeters and greeters” account for five to ten percent of total journeys. The definition of what a “visitor” is can dramatically affect the importance of this category. In a report by the Committee on Transportation to and from Airports of the Technical Council on Urban Transportation (1969), the category “visitors” includes groups such as sightseers, salesmen and service and repair personnel while de Neufville and Odoni (2003) do not consider the category “visitors” in their assessment of the surface access market at all. They state that the split between the other three categories in terms of total trips to the airport is at least 20 percent for each category. This potentially leaves a further 40 percent unaccounted for. Ashford et al (1997) separate “senders and greeters” from visitors. They also appear to discard suppliers as being less important although de Neufville and Odoni state that they generate a comparable number of trips to passengers and employees. All of the varying accounts highlight that there can be considerable variations within each category attributable to local conditions and characteristics.
Table 2.1: Proportion of Passengers, Employees, Visitors and Senders/Greeters at Selected Airports
Table 2.1 details the split of the airport population for a number of international airports.
Although dated, the figures highlight how the size of each category can vary widely between airports.
Airport Passengers Senders and
Source: Ashford et al (1997, p.413)
The airport “population” differs to the number of “access trips” made to and from the airport. In a day, each passenger generally accounts for a trip to or from the airport whereas employees and visitors account for a trip to and from the airport. Suppliers and visitors will also typically make a trip to and from the airport. As each employee, visitor or supplier accounts for two access trips, their importance in the access system is more pronounced than it is when looking at the airport population. (Committee on Transportation to and from Airports of the Technical Council on Urban Transportation, 1969)
The proportion of trips that each category of surface access user contributes to the total number of surface access trips depends on the local conditions present. For example, the proportion of surface access trips made by passengers may be reduced at large airports where there are more transfer passengers and the proportion of surface access trips by employees may be greater when an airline maintenance or training base is located at an airport. (Humphreys, 1996, de Neufville and Odoni, 2003)
Generally, as the usage of an airport increases, the rate of ground access vehicle trips decreases. Research carried out at airports in California highlights this and is shown in Table 2.2. Airport usage can be defined as the number of passengers boarding aircraft or million annual passengers. Further studies at other U.S. airports supports the trend that the largest airports generate the fewest vehicle trips per passenger, while the smallest generate the most
vehicle trips per hour. The figures in Table 2.2 only relate to passenger trips. Extra trips are also generated by employees and the movement of goods. At large cargo handling hubs, such as Los Angeles and San Francisco in the California study, an extra 40 percent of trips can be generated by these two categories. (Higgins, 1994)
Table 2.2: Million Annual Passengers and Passenger Vehicle Trips per Day at Californian Airports
Airport Million Annual Passengers Passenger Vehicle Trips per Day
Los Angeles 45.81 1.36
Source: Adapted from Higgins (1994, p. 104)
2.2.2 The Employee Surface Access Market
Passengers are only part of the airport access problem and there is often a misplaced focus on this segment of the market. This misplaced focus is often because of the large numbers of air passengers using the airport relative to the population of the urban area served by the airport. At the same time the relative number of employees is low, typically less than 0.8 workers per 1000 passengers (de Neufville and Odoni, 2003). This is shown in Table 2.3 which relates to U.S. airports. Table 2.3 also includes the average daily number of employees as a percentage of daily passengers. This column highlights the differences which exist at airports. For example at San Diego the proportion of employees is low at 6.2 percent while at San Francisco/Oakland it is high at 41.6 percent. The majority of the airports lie within 12 and 30 percent range although this still gives scope for considerable variation.
Table 2.3: Sample Data on the Number of Employees at U.S. Airports
Airport Average
St. Louis/Lambert 19,000 0.66 24.1
Source: Adapted from de Neufville and Odoni (2003, p.698)
A different perspective is offered by Bonnet (1980) who suggests that the number of employees required at an airport is a function of the number of passengers using the airport and that as the number of passengers increases, the relative number of employees decreases.
While this may be true for passenger terminal operations it does not consider that the number of employees also varies depending on the local conditions at the airport, for example as stated earlier if an airline has a maintenance base or there is a large cargo facility.
Although the share of the airport population accounted for by employees is generally less than 30 percent of the number of passengers it is important to consider the frequency of travel when looking at the airport surface access market. Each originating or terminating passenger only makes one surface access journey and the average number of journeys per passenger is usually less than one because people share car journeys to the airport. For example, a family of four will travel to the airport together meaning that each of the passengers only accounts for 0.25 journeys. Employees, however, make at least one round trip every day which accounts for approximately 500 trips per employee per year. The frequency of employee trips compensates for the low number and therefore makes it the same order of magnitude as passenger traffic. For example an airport with ten million passengers annually will have between seven and nine million passengers making trips to and from the airport because some passengers will be transferring and not making use of the surface access system. This implies approximately 20,000 – 25,000 passenger trips to and from the airport each day. If 5,000 people work at the airport every day, which is consistent with a ratio of about 0.5 employees per thousand passengers as shown in Table 2.3, then the
number of employee trips accounts for 10,000 a day on average. This highlights the importance of employee access journeys. (de Neufville and Odoni, 2003)
The importance of the employee in surface access terms is stated by Caves and Gosling (1999, p.161) in that, “Much of the local traffic generated by an airport is associated with the workers rather than the passengers…” but they also recognise that airports tend to focus on passengers where surface access is concerned, “…but the competitive nature of airports requires attention to the passengers’ quality of service.”