UFC 3-260-03
15 Apr 01
c. Drainage and Ground-Water Conditions. First, the general surface-drainage system for the area
should be ascertained. The natural drainage pattern can be established from contour maps published by
the U.S. Geological Survey, the National Oceanic and Atmospheric Administration, or the National
Imagery and Mapping Agency (NIMA). Detailed information will be collected concerning drainage at the
airfield, including descriptions of any drainage installations and shoulder slopes, and whether excessive
vegetation or soil has built up along the pavement edges sufficiently to pond water on the pavements. The
depths to ground-water tables in the vicinity and at the airfield property should be determined, and the
presence of any perched water tables in the airfield subgrade will be noted. Information concerning
ground-water tables can be obtained from well logs, cuts, or borings in the vicinity, and the location of
springs and seeps. Subsurface drainage systems must also be identified and evaluated.
d. Climatic Data. Information on climatic data can be extracted from routine National Weather
Service publications and from records of the airfield weather station. For the period of record, the climatic
data should include average daily maximum and minimum temperatures for each month, average annual
rainfall, freezing index, average humidity, and description of the prevailing winds.
e. Maintenance. Detailed information should be obtained on the maintenance performed on each
facility. The dates when application of such items as seal coats, surface treatments, and patches should
will be ascertained, and the reason for performing the work should be explained in all possible detail.
Files of the Facilities Engineer, Base Civil Engineer, or responsible construction office should contain this
information.
f. Current Condition of Pavements. A detailed survey should be made of the pavement surface on
all facilities. Procedures for condition surveys of existing pavements are presented in ASTM D 5340.
g. Airfield Traffic Data. For a pavement evaluation to be meaningful, it is essential to have some
measure of normal and expected traffic in terms of repetitions and loading characteristics. Thus, the
traffic data collected must include the type of aircraft, gross weight, and typical operating weights of each
type aircraft regularly using the airfield on a day-to-day basis.
5.
OPERATIONAL CONSIDERATIONS.
a. Intensity and Repetition of Load. The primary factors influencing the load-carrying capability of
an airfield pavement are the thickness and strength of the pavement layers, distribution of the induced
loading (gear configuration and tire pressure), and number of repetitions of loads by the aircraft. Airfield
pavements may be evaluated to:
(1) Determine the number of repetitions of an aircraft that can use a pavement at a designated
gross weight.
(2) Determine the allowable gross weight of an aircraft that can use a pavement for a given
number of repetitions.
(3)
Determine what effect past aircraft operations have had on pavement life.
(4)
Determine PCN for the day-to-day traffic or for specified standard traffic.
b. Aircraft Grouping for Air Force Evaluation. To reduce calculations and simplify the evaluation
procedure, operational aircraft have been divided into 14 aircraft groups designated by an Aircraft Group
Index for Air Force evaluations as shown in table 2-1. As noted, the table contains a listing of all appro-
priate operational aircraft that may be expected to use Air Force airfields for various purposes. A con-
trolling aircraft (aircraft having the most severe loading) was selected for each landing assembly
2-4
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