UFC 3-260-02
30 June 2001
monthly traffic periods should be adequate. For design purposes, it is best to use the long-term
averages such as the 30-year averages given in the annual summary. The determination of the design
pavement temperatures for 254-millimeter (10-inch) bituminous pavement can be demonstrated by
considering the climatological data for Jackson, MS. For the month of August, the average daily mean
temperature is 27.5 degrees Celsius (81.5 degrees Fahrenheit) and the average daily maximum is
33.6 degrees Celsius (92.5 degrees Fahrenheit); therefore, the design air temperature for consideration
of the subgrade strain is 30.5 degrees Celsius (87 degrees Fahrenheit), and the design pavement
temperature (determined from Figure 11-1) would be approximately 37.8 degrees Celsius (100 degrees
Fahrenheit). For consideration of bituminous fatigue, the design air temperature for August in Jackson is
27.5 degrees Celsius (81.5 degrees Fahrenheit), resulting in a design pavement temperature of
approximately 33.3 degrees Celsius (92 degrees Fahrenheit). These design pavement temperatures are
determined for each of the traffic periods. Temperature data for Jackson (from "Local Climatological
Data Annual Summary with Comparative Data, Jackson, Mississippi") are shown in Table 11-1.
Table 11-1
Temperature Data for Jackson, Mississippi
Temperature, degrees C (degrees F)
Month
Average Daily Maximum
Average Daily Mean
January
14.7 (58.4)
8.4 (47.1)
February
16.5 (61.7)
9.9 (49.8)
March
20.4 (68.7)
13.4 (56.1)
April
25.7 (78.2)
18.7 (65.7)
May
29.4 (85.0)
22.6 (72.7)
June
32.8 (91.0)
26.3 (79.4)
July
33.7 (92.7)
27.6 (81.7)
August
33.6 (92.5)
27.5 (81.5)
September
31.1 (88.0)
24.4 (76.0)
October
26.7 (80.1)
18.8 (65.8)
November
20.3 (68.5)
12.9 (55.3)
December
15.8 (60.5)
9.4 (48.9)
(2) Thaw periods. The effects of temperature on subgrade materials are considered only with
regard to frost penetration. The basic requirement of frost protection is given in Chapter 20. If the
pavement is to be designed for a weakened subgrade condition, the design must consider a period of
time during which the subgrade will be in a weakened condition.
(3) Subgrade moisture content for material characterization. In most design situations,
pavement design will be predicated on the assumption that the moisture content of the subgrade will
approach saturation. If sufficient data are available that indicate the subgrade will not reach saturation,
then the design may be based on a lower moisture content. Sufficient data for basing the design on a
11-2
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