30 June 2001
d. Example 4.
(1) The design curves may be used to design an airfield pavement for a mix of aircraft traffic.
This example will demonstrate the procedure for an Air Force airfield using the aircraft, gross weights,
and pass levels shown in Table 10-1. The subgrade has a CBR of 6 and the traffic area is type B.
(2) The procedure is demonstrated as follows using Table 10-1 as an example.
Column 1. List aircraft to be considered in design.
Column 2. List pavement design curve figure no. for respective aircraft.
Column 3. List gross weight of aircraft at which they will operate on pavement.
Column 4. List number of passes anticipated at indicated gross weight.
(e) Column 5. Select the thickness required for each aircraft at the pass level and gross
weight shown from the appropriate design curve (Figures 10-1 to 10-32).
(f) Column 6. Determine the pass level permissible for each aircraft for the greatest
thickness in column 4. The C-141 and the F-15 both require 635 millimeters (25 inches) of total
thickness. In this case, the larger aircraft would normally be selected for comparisons, although it may
be necessary to check design in terms of both aircraft. The C-141 is therefore selected for comparisons.
The design curves are entered with the subgrade CBR of 6, then move downward to intersection with
the aircraft gross weight curve, then horizontally to intersection with the 635-millimeter (25-inch)
thickness line. The pass level occurring at this intersection should be recorded in column 6.
(g) Column 7. Divide the passes in column 6 by the passes permissible at
635 millimeters (25 inches) for the C-141 (1,000) and enter in column 7. Column 7 gives the equivalent
passes on a 635-millimeter (25-inch) pavement by each aircraft in terms of one pass of the C-141. That
is, one pass of the C-141 is equivalent to 1.2 passes of the B-52 or is equivalent to 7.5 passes of the
(h) Column 8. Divide the number of passes in column 4 by the equivalencies in
column 6 to determine the design passes in terms of the C-141 and record in column 8. The total
equivalent passes of all aircraft in terms of the C-141 is 2,910. Figure 12-31 is entered with the
subgrade CBR of 6, the C-141 gross weight of 145,150 kilograms (320 kips,) and the equivalent pass
level of 2,910 to select the required thickness of pavement of 711 millimeters (28 inches). The thickness
of the individual layers will then be determined in the conventional manner using the minimum
thicknesses of pavement and base for the C-141.
7. STABILIZED PAVEMENT SECTIONS. Stabilized layers may be incorporated in the pavement
sections to make use of locally available materials which cannot otherwise meet the criteria for base
course or subbase course. The major factor in deciding whether or not to use a stabilized layer is
usually economic. Additional factors include moderate reduction of the overall pavement section and
increased design options. The strength and durability of the stabilized courses must be in accordance
with requirements of Chapter 9. For Air Force and Army, see requirements in TM 5-822-14/
AFJMAN 32-1019. For Air Force design, stabilized subbase may not be used without a stabilized base
unless the base course has adequate drainage. (Approval from Air Force major command is required
when use of stabilized components is contemplated.)