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Design Hour Determination Model
Analysis Techniques
The design hour for passengers historically has had a number of definitions. One approach is
to define the design hour as the 90th (or 95th) percentile busiest hour of the year. Determining
this hour requires keeping track of all of the enplaning and deplaning passengers for every flight
during the year, and then ranking these by hour (usually a clock hour) to find the level of activ-
ity that accounts for 90% of the annual traffic. While used by some non-U.S. airports, it is a very
data-intensive approach for which data is not available for the vast majority of U.S. airports.
In the United States, peak hour passengers are typically defined as peak houraverage
daypeak month passengers and are also often referred to as the "design hour passengers." This
User's Guide will use the term "design hour passengers" for consistency. The design hour mea-
sures the number of enplaned and deplaned passengers departing or arriving on aircraft in an
elapsed hour of a typically busy (design) day. The design hour typically does not correspond
exactly to a clock hour such as 7:007:59 but usually overlaps two clock hours (e.g., 7:208:19),
reflecting airline scheduling patterns.
Design Hour Demand
The design hour is not the absolute peak level of activity, nor is it equal to the number of per-
sons occupying the terminal at a given time. It is, however, a level of activity, which the industry
has traditionally used to size many terminal facilities. The total number of people in the termi-
nal during peak periods, including visitors and employees, is also typically related to design hour
passengers.
The focus of the Design Hour Determination model is on scheduled seats. These can easily be
converted to passengers with the use of an assumed average load factor (percentage of seats
filled). The model sets up the determination of the design hour in such a way that most segments
of interest can be determined at the same time (i.e., Domestic/International, Air Carrier/Regional,
and Arriving/Departing/Total).
The peak month is described in the model as a percentage of annual passengers based on his-
torical patterns. This percentage may be modified for future years based on local trends and/or
anticipated changes in air service patterns. The peak month may be different for enplaned and
deplaned passengers, domestic and international, and so forth. Depending on the number of
days in the month, an average day is calculated.
An alternative to using the average day of the month is to use an average weekday. This is often
done at airports where domestic service is the predominant activity and weekend activity is less
9
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10 Airport Passenger Terminal Planning and Design
than weekday activity. Airport records on monthly and daily passenger volumes (as recorded by
the airlines) is the best source for determining whether an average day or an average weekday is the
appropriate (design) day for the design hour.
If a flight schedule is not being developed, the design hour is estimated as a percentage of
daily activity. These percentages (enplaned and deplaned) should be based on actual passenger
activity data collected from the airlines for a typical week. As with the peak month, percentages
may be modified for the future based on local trends and/or anticipated changes in air service
patterns.
The Design Hour Determination model is driven by actual passenger traffic data to systemat-
ically calculate the planning factors that could be used later, in the absence of a design day sched-
ule, to estimate design hour activity. The model's structure takes the user through each required
step with simple instructions and directions for when to go to the next step. Each tab of the
spreadsheet has a blue instruction box with step numbers corresponding to the numbered areas
requiring an action in the worksheet. The user must still gather the necessary data for each step,
but the process should be simple to follow by doing the actions in the right order.
Figure 7 shows the tab structure for the Design Hour Determination model. The user has com-
mand buttons in each tab that when clicked will jump to the next tab in the right order or the
user can just click on the worksheet tabs at the bottom of the screen and follow them in order
from 1 to 7.
Figure 8 is a screen print of the first tab of the Design Hour Determination spreadsheet. The
user gathers monthly enplanement data and enters it into the input cells, and the normal peak
month is determined. The spreadsheet functions can be seen in the light green calculated cells to
observe the processes that are being used. The process is not difficult, and the spreadsheet is
doing some of the work automatically for the user. Once the peak month is determined, an aver-
age week from Sunday to Saturday needs to be selected. The user should select a week that does
not contain holidays or other anomalies.
Operations and scheduled seats data from the average week of the peak month is then gath-
ered and entered into the input cells on Tab 2 (Figure 9), which helps determine an average day
during the peak month. The user must determine the actual day of the month for the selected
average week, typically choosing Sunday as the start of the week. Enter that day into cell B9. All
of the steps for Tab 2 are again listed in the blue instruction box and the action areas are high-
lighted with corresponding numbers. The user can observe the percent difference or variation in
Step 4 to help in choosing the design day, which will provide the data for the peak hour deter-
mination in the following steps. Although the model is set up to use scheduled seats, actual pas-
senger and operations data for the week would be preferable if it is available.
After determining a design day (normally a Wednesday or Thursday) that most closely
resembles the peak month average week's daily average, a complete schedule of arriving and depart-
ing seats for the design day during the peak month is needed for the next step, which will gen-
erate 10-minute buckets that will be used to create rolling hours throughout the day. The
actual design rolling hour is then determined automatically and traffic charts are generated on
TAB 6 with the corresponding data to better describe the chart activity. The complete schedule
can be acquired from recent airport data or from the Official Airline Guide (OAG). The OAG
data will be actual seats flown or scheduled seats to be flown if the peak month average day is
very near in the future.
Figure 7. Tab structure of the Design Hour Determination model.
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Design Hour Determination Model 11
Figure 8. Tab 1 example of the Design Hour Determination model.
Figure 9. Tab 2 example of the Design Hour Determination model.
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12 Airport Passenger Terminal Planning and Design
Tabs 3 and 4 are set up to be simple for the user to input the airport or OAG data into the input
blocks starting at Row 5 in Column A. Copy and paste the schedule data, as is, into these columns
and then update the Pivot Table, if there are international markets that need to be identified. The
instructions for these tabs stress the need for the time of departure or arrival to be in the 24-hour
format. This format is normally the default time setting, but if not, it will need to be adjusted for
the model to work properly.
The determination of international and domestic markets was not automated so that in the
cases of preclearance efforts, those markets could be treated as each individual airport sees fit. If
no markets are selected as international, then there will be no design hour international segment
identified. In Tabs 3 and 4, there is a section that is titled "Designation Table for Dom/Int"; this
section has a built-in Excel Pivot Table. The section will become populated with a summary of
each destination or origin airport when the Update Pivot Table button is clicked. This button
was added so that when the international and domestic segments were truly desired, the user
would only have to select each international market once instead of going through what may be
a lengthy list and checking for multiple listings. Figure 10 shows Step 5 where "D" or "I" will be
selected from a drop down list, and Figure 11 shows the populated table from when Step 3 is
completed.
Certain airport markets may have a unique mix of regional aircraft, and the appropriate desig-
nation as either air carrier or regional may not always follow the FAA guidelines, which use 60 seats
as the threshold between air carrier and regional. Cell F3 uses 60 seats as the default, which resets
when all the inputs are reset, but allows the user to choose the level that best fits the mix of local
aircraft and how that mix is interpreted. By adjusting the Regional Level Factor (Step 4) as pointed
out in Figure 12, the user can control which aircraft will be considered regional and air carrier.
The arrival and departure data that is entered into Tabs 3 and 4 will automatically be orga-
nized into 10-minute buckets and rolling hours on Tab 5, which is basically an organized sum-
mary sheet that displays the design hour for arriving, departing, and total seats, as shown in
Figure 13. With specific knowledge of the operations at local airports, the determined design
hours should be within the expected range based on personal experience of the user.
The model highlights the peak bucket and rolling hour period in each section with yellow and
red markings (Figure 14). In addition, the percentage of the design day that the design hour rep-
resents is also calculated within this tab and will be displayed on Tab 7, Design Hour Forecast.
Figure 14 also shows the top of the table on Tab 5 where Row 7 contains the percentage of daily
activity that the design hour--for arriving, departing, and total seats--represents.
Figure 10. Tab 3, Step 5, example of the Design Hour Determination model.
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Design Hour Determination Model 13
Figure 11. Tab 3, Step 3, example of the Design Hour Determination model.
Figure 12. Tab 4 example of the Design Hour Determination model.
