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108 Guidebook for Conducting Airport User Surveys Similarly, departing passengers who are visitors to the area may be able to recall information about greeters who met them on their arrival, but they may not know how long those greeters spent at the airport or whether they used any airport services or concessions while waiting. Departing passengers who are residents of the area are less likely to be able to provide informa- tion about greeters who will meet them on their return, because this has yet to take place. Therefore, it may be desirable to survey greeters and well-wishers themselves in non-secure parts of the airport. This is especially true if it would be useful to have information on their use and satis- faction with the facilities, services, and concessions, or to obtain their suggestions. Because it will not always be obvious who are passengers and who are greeters or well-wishers without asking them, information on greeters and well-wishers will generally be obtained as part of a survey that includes passengers as well, but using separate questionnaires or separate questions on a common question- naire. These surveys are typically performed at the various groundside locations. The problems with sampling bias are more acute with greeter and well-wisher surveys than passenger surveys. Well-wishers will often not want to take the time to participate in a survey during the short period they have with the passengers, and they will typically not remain in the terminal long after the passengers proceed though security. Greeters are usually easier to inter- view as they wait for the passenger to arrive, but the sample will be biased towards greeters who spend a longer time at the airport, especially for delayed flights. This bias can result in biased esti- mates of characteristics such as the time spent in the terminal, the time their vehicle is parked, and the amount spent at the concessions. Care must be taken to ensure that greeters and well-wishers are not double-counted when ana- lyzing the results of surveys of air passengers in which multiple responses may be received from a given air travel party. Greeters and well-wishers will usually be at the airport to see off all mem- bers of the air travel party, which must be taken into account when tallying the numbers of greeters and well-wishers per passenger. There will often be more than one greeter or well-wisher meeting or seeing off an air travel party, but only one survey response will be obtained from each group. Thus the number of greeters or well-wishers in the group should be collected, as well as the size of the air travel party they are meeting or seeing off. Care should also be taken in express- ing the results to account for air travel parties that do not have greeters or well-wishers. In the case of well-wishers, this information can be obtained from air passenger surveys. However, esti- mating the number of arriving air parties that are not met is more difficult. The total number of greeters and well-wishers can be estimated by comparing the reported use of short-term park- ing by greeters and well-wishers with statistics on exits from short-term parking by duration. 5.9 Groundside Surveys Groundside surveys form a special type of air passenger survey that can be used to obtain detailed information for planning airport groundside facilities. Groundside surveys are charac- terized by two key factors: first, the survey sample is typically not a controlled random sample of the target population; and second, the interview process is directed at the occupants of a vehicle rather than individual travelers. In the absence of a structured sample plan from which to derive weight factors for each interview, it is necessary to obtain ancillary data in order to calculate appropriate weights for the survey responses. 5.9.1 Purpose Groundside surveys are used to gather information on vehicle use patterns by air passengers and associated greeters and well-wishers to plan future groundside facilities or to create and cal- ibrate a ground transportation model that will be used in future planning studies.

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Air Passenger Surveys 109 The vehicle trips associated with the passengers on a single flight place loads in time and space on the groundside facilities. The sum of these loads for all flights in a planning period gives the varying load on all groundside facilities, which determines the resulting level of service provided by those facilities. Groundside surveys are designed to collect complete information on the vehicle trips serving arriving and departing air passengers, including the characteristics of the well-wishers and greeters that accompany those passengers. This information enables the development of four time curves associated with air passenger departure and arrival activity: The time before flight departure that air passengers and any accompanying well-wishers arrive at the airport. The time well-wishers leave the airport, either before or after the flight departure. The time that greeters arrive at the airport with respect to the arrival time of the flight they are meeting. The time that air passengers and any accompanying greeters leave the airport after the flight arrival. 5.9.2 Ancillary Data To handle the sampling rates of this type of survey during the analysis, it is necessary to ensure the survey population is well defined. Groundside interviews will yield air passenger informa- tion linked to specific flights. Therefore, to know how each interview should be factored so that the survey results represent the characteristics of all O/D air passengers, passenger counts should be obtained for each flight. In the case of through flights, it will be necessary to obtain counts of both the terminating and originating passengers. If passenger loads on each flight are not available from the airlines or the airport, they must be estimated using an alternative data source. The airline schedule for the airport can be obtained prior to the survey for the survey period from the OAG or similar sources. This dataset will pro- vide scheduled arrival and departure times, along with aircraft type, from which the number of seats can be estimated. Recent data from the airlines can be used to apply load factors to each flight, by flight sector, to generate estimates of enplaned and deplaned passengers. Since connect- ing passengers do not use the groundside facilities, they must be subtracted to obtain estimates of O/D passengers.24 A key aspect of groundside surveys is that the interview is directed at the occupants of vehi- cles, rather than a group of air passengers. With this in mind, the survey planning team must be able to supplement the interview process with data from traffic counts, possibly in combination with other data sources. The factoring process, involving vehicles as the base unit, requires data from a variety of sources so that the interviews of the occupants of each vehicle can be made rep- resentative of the population. These data sources include the following: Parking ticket data--to factor the interviews at the parking lots. Curb activity--to factor the interviews at the curbside, including both the public vehicle area and taxi queues.25 24 Quarterly data on connecting passengers by airline and flight sector can be estimated from the U.S. Department of Trans- portation Bureau of Transportation Statistics airline Origin/Destination Survey database. 25 Information on conducting curb activity surveys can be found in the documentation for the 2005 Groundside Survey at Toronto Pearson International Airport (see the Bibliography).

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110 Guidebook for Conducting Airport User Surveys Rental car activity--to factor interviews in the rental car area, both pick-up and drop-off. Hotel courtesy vehicles, rapid transit, and other public modes--possibly obtained from AVI systems. 5.9.3 Staff Requirements Temporary staff requirements always drive the cost of an interview survey. With groundside surveys there is considerably more latitude in defining these requirements, although the required sample size remains a governing aspect. Whether the survey is covering the entire airport for a short period or covering well-defined segments at different times over a longer period (as discussed in Section 5.9.4), the requirements will be about the same in terms of the total number of interviewer-days. While the calculation of the survey sample size, discussed in Section 5.3, is a key considera- tion, interviewer requirements are also determined by the number of locations that need to be surveyed to ensure representative results. This need for enough interviewers to cover all loca- tions may result in a higher number of survey responses from some locations than is required to meet the minimum requirements for desired statistical confidence. The following interviewer staffing guidelines are based on an extensive groundside survey at Toronto Pearson International Airport in 2005: Curb area: Three interviewers per terminal door for a single multi-use curb. Two interviewers per terminal door for a public use (inner or outer)26 curb area. One interviewer for each taxi queue (arrivals area). One interviewer for each of four designated stops for local bus or other services (shared- ride taxi, shuttle services, hotel courtesy, etc.) in arrivals area. Parking areas: One interviewer per ticket spitter entrance area for a parking lot, or Two interviewers per "pay on foot" parking payment machine area. Rental car and remote parking: One interviewer per pick-up area, where the rental vehicle is picked up adjacent to the terminal. One interviewer per drop-off area, where the rental vehicle is dropped off adjacent to the terminal. One interviewer for each shuttle pick-up area for remote locations where air passengers are picked up adjacent to the terminal by a shuttle service that takes them to a remote or off- airport car rental agency or parking facility. (Where shuttle service for remote or off-air- port vehicle drop-off or parking is provided, the interview coverage is typically provided by the curb interviewers.) Supervision requirements will vary with the airport configuration and experience of the inter- view staff and should be included in estimating staffing levels. These guidelines should be used in conjunction with the requirements for sample size and the information in Table 5-4 showing the approximate number of responses per interviewer expected under different conditions. 26 Inner curb areas are adjacent to the terminal and, at Toronto Pearson International Airport, are reserved for taxis, limou- sines and the like, while outer curb areas are dedicated to public use.

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Air Passenger Surveys 111 Table 5-4. Number of responses expected per interviewer by groundside location. Estimated Number Area Conditions of Interviews per Eight-Hour Shift Curb--public and taxi Constant high volume of activity throughout the survey 150 drop-off period, first door of the terminal Curb--public and taxi Constant high volume of activity throughout the survey 125 drop-off, public pick-up period, second and subsequent doors of the terminal One peak period of activity and lower volumes during the 100 shift Curb--taxi waiting queue As long as there are passengers waiting in the queue 150 Curb--shuttle stops N/A 80 Parking--ticket spitter Primary entrance to the parking lot; when traffic is heavy, 125 the proportion of vehicles interviewed will be lower Parking--"pay on foot" As long as there are passengers waiting in the queue 150 Rental car--pick-up Single lobby area for multiple agencies, or interviewers 100 move between agencies during shift Rental car--drop-off Common drop-off area for all agencies, or interviewers 100 move between drop-off areas Rental car or remote Pick-up area for service to remote area; rate assumes a lower 50 parking--shuttle service volume of activity than in rental car lobby area These estimates are based on the use of well-trained interviewers who can approach a vehicle, engage the party in the interview, and then complete a 20-question interview (including some observation entries) in less than two minutes. 5.9.4 Time and Space Considerations Large international airports have multiple terminals and groundside facilities. Groundside sur- veys must be conducted at numerous locations and across the whole day of airport activity, from 6:00 a.m. (or earlier) to 11:00 p.m. (or later). This time span calls for at least two shifts per day of interviewers. The groundside survey design, however, will not necessarily require that all terminals and all areas be covered at the same time. For medium- to large-sized airports, such a requirement would take an enormous and unwieldy number of interviewers for short periods of time. Instead, the airport or terminal can be subdivided in time and space to make the survey more manageable. For this subdivision process, the survey design must maintain the link to the ancillary data so that the weighting can be completed for the analysis. Air passenger volumes will naturally divide into departing and arriving segments, as well as by terminal, and these volumes can be deter- mined independently. In the analysis, it will then be possible to generate a weighting factor for each interview with a departing passenger as a function of the number of originating passengers. Similarly, the groundside curb areas are often divided into separate arrival and departure areas. Under these conditions it is possible to design a groundside survey that segments the pop- ulation into distinct groups, each of which can be surveyed independently. As an example, consider the following survey plan for a single terminal with an upper level departures area and a lower level arrivals area. The departures level has a single curb, while the arrivals level has an inner and outer curb with taxis and buses at the inner curb and the general public at the outer curb. In addition, there are "pay on foot" parking payment machines at two locations in the terminal, a single lobby for the rental car agencies, no off-site remote service, and a common drop-off location for all rental car agencies. Table 5-4 shows the expected interview

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112 Guidebook for Conducting Airport User Surveys completion rates per eight-hour shift for very short, focused interviews conducted by efficient interviewers. Note that completion rates depend on the length of the questionnaire, traffic vol- umes and flows, and the method used to conduct the interviews and, in some cases, may be sig- nificantly less than the rates shown. Actual completion rates will vary over the day, as traffic volumes vary. Table 5-5 shows the corresponding interviewer staffing requirement for this example. Note that fewer interviewers are required for the departures area than the arrivals area, which is quite common. With the interviewer resources established for each area, it is then a matter of making up a schedule of at least two shifts per day, so that the arrivals and departures areas are surveyed an appropriate number of times during the survey period. Based on the required number of inter- views, the number of shifts and therefore the number of days required for the survey can be cal- culated. The shift plan will also have to cover each direction for each day of the week, so that, for example, an early shift for arrivals on each day of the week and an early shift for departures on each day are both included in the survey design, and likewise for the late shift. The survey design should also ensure that staff assigned to a late-night shift are not assigned to the next early-morning shift. It is assumed that week-to-week differences in the traffic pattern will be negligible. With this plan in effect for a terminal with an adequate volume of traffic throughout the day from 6:00 a.m. to 11:00 p.m., each shift of interviewers will perform 1,500 to 2,000 interviews. This example demonstrates why the sample size is less of a concern than the coverage in time and space and the correct weighting of responses. When the survey is conducted over a week or more, the numbers of responses at each individual survey location are usually sufficient for detailed planning purposes. 5.9.5 Questionnaire A generic groundside interview form should be developed first, to lay out the specific ques- tions and establish the overall flow of the form. This form will then be modified to suit each of the interview locations for the survey. Experience has shown that interviewers have difficulties with a generic form that covers both activities that have already occurred and those that are yet to occur. Arriving passengers did some things in the past that departing passengers will do in the future. Keeping the past and future verb tenses in a logical order on a generic form is not easy. Therefore, it is preferable to design forms for each survey location and air passenger direction. The first part of the form will contain observation information that the interviewer can complete as the target vehicle is approached. This information includes the interviewer, interview number, Table 5-5. Example of number of interviewers required. Area Interviewers Departures Area Departures curb--3 doors into terminal 9 Bus and shuttle drop-off 3 Rental car drop-off 1 Arrivals Area Arrivals curb--inner area, 12 stops, plus 2 taxi queues 5 Arrivals curb--outer area, 3 doors 6 Parking payment machines 4 Rental car pick-up lobby 1

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Air Passenger Surveys 113 time, location, vehicle type, number of occupants, and number of pieces of baggage (where bag- gage is visible). Standard rules for counting people and baggage must be defined, such as: Any child over the age of two is counted. All baggage is counted, except purses. After a short introduction, the first question should always be: Have you been interviewed at the airport today? This question has several purposes: to remove undue survey burden on the airport users, to elim- inate duplicate information, and to count the number of vehicles that go to two groundside facil- ities in one airport trip. For departure trips visits to two groundside facilities could involve a stop at the curb followed by entry to the parking lot. For arrival trips it could involve the opposite, with exit from the parking lot followed by a stop at the curb to pick up passengers and baggage. One section of the form will deal with the purpose of the vehicle trip: dropping off air passen- gers, picking up air passengers, or other activities (e.g., buying tickets, using airport concessions, or checking baggage for a later flight). While there will be several response options on the generic form, the number of responses on the form for each survey location may be reduced to a few or only one. For example, at the taxi drop-off or taxi queue areas, there are usually only air passen- gers; therefore, response options that greeters or well-wishers could choose would not appear on the survey form for those locations. Another section will deal with the trip origin or destination within the local area. At departure locations this section typically appears early on the form, whereas with arrival locations this section should be later. These questions will include the type of trip origin or destination and a geographical location, as discussed in Section 5.4. Another section will cover the air trip, which includes the number of air passengers (in this vehicle) as well as the baggage that was (or will be) checked. Experience has shown that air passen- gers usually do not know their flight number, but they do know the airline, where they are coming from or going to, and the approximate time of arrival or departure. A question about whether there will be a transfer en route to the final destination is normally required. This information is usually sufficient to identify the flight on which the air passengers are departing or arriving. A final question will ask whether the air passengers are residents of the area served by the air- port or are visitors to the area. Asking air passengers for their city and zip code (postal code) of residence can allow responses to be classified appropriately without relying on the respondent to decide whether they consider themselves a resident or a visitor, and can provide useful addi- tional information to resolve ambiguous cases. A sample set of groundside interview forms that were used in the 2005 Groundside Survey at Toronto Pearson International Airport is provided in Appendix G. 5.9.6 Calculating Response Weighting Factors Each groundside survey interview will have a number of different response weights attached to it at the time of analysis. These weights will all be calculated from the proportion of interviews to a given population. During the analysis, the appropriate weights can then be applied to the responses. Following is a partial list of weighting factors and the source data that are required to calcu- late the corresponding weights: Vehicle counts, possibly by mode. Given the total number of private vehicles that stopped at the departures curb and the number of vehicle occupant interviews in a specific time period,