log E3 =


4.970 + 0.1773(t1) 1.6966 log(t ) 0.1069(D4)

+ 0.2552(D7) 2.6546 log(D1) 3.9906 log(D3)

+ 1.8241 log(D ) + 3.5092 log(D2 D5)


 Eqn. 6.13

 R2 = 0.887 and N = 22



 Error analysis indicated that one pavement (SR 15B) had -34.6

percent prediction error. The actual E value was 50.0 ksi, while

the predicted value was 32.7 ksi. Others had prediction errors

generally less than 15 percent.

 Equation 6.13 for the prediction of E3 applies to a slightly

wider range of variables than Equation 4.24 which was selected from

the theoretical analysis. However, the latter is more simplified

and contains fewer variables than Equation 6.13. Also, since the

R2 value is greater, Equation 4.24 should be used for E3 predic-

tions.


 6.7.3.2.4 Subgrade modulus, E4. Regression

against either D or D or both resulted in the

tions:


 E = 53.697(D )-1.041
 4 6


(R2 = 0.997 and N = 22)


E = 39.690(D )1.004
4


(R2 = 0.999 and N = 22)


analyses of E4

following equa-




 Eqn. 6.14


Eqn. 6.15