Table 12. Estimated mean top of the subgrade
temperatures (C) from FROST.
Subgrade
Air
Interstate
Rural
January
8.2
0.2
1.2
February
10.4
1.5
3.0
March
1.3
0.5
1.0
April
5.0
1.9
2.2
May
15.1
11.0
13.2
June
18.1
18.5
21.4
July
21.4
21.6
24.9
August
19.9
18.6
21.7
September
14.5
18.8
20.4
October
8.0
12.7
13.1
November
4.0
8.8
8.7
December
6.5
2.0
0.7
Table 13. Temperatures for selecting subgrade modu-
lus.
Temperature (C)
Months
Interstate
Secondary
January
0.5
1.5
February
1.5
3.0
March
1.0 & 0.1
3 & 0
April
0.5 & 4
0&3
May
11
13
June
18
21
July
22
25
August
19
22
September
19
20
October
13
13
November
9
9
December
2
2&0
19
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