458


3. Check whether measured deflections are within the following limits:

 0.56 < D1 or D < 2.92 mil

 0.27 < D < 2.07 mil

 0.15 < D4 < 1.50 mil

 0.05 < D5 < 1.00 mil

 and also the following criteria are met:

 0.09 < D0 + 02 203 < 0.85 mil

 0.12 < D3 D4 < 0.57 mil.

 These criteria conform approximately to the following range of layer

 moduli and thicknesses:

 65.0 < E < 400 ksi 1.5 < t1 < 8.5 in.

 26.0 < E < 130 ksi 6.0 < t < 24.0 in.

 18.0 < E3 < 90.0 ksi 12.0 < t3 < 36.0 in.

 5.0 < E < 105 ksi t4 = semi-infinite

 Note that for the prediction equations, Ei is in ksi, ti in inches,

 and Di in mils. Also extremely high or low Ds values, outside the

 stipulated range, may be used for estimates of E4 from 1.0 to 200

 ksi.

4. If the above conditions are satisfied, proceed to step 5. If not,

 check deflection measurements and then go to step 3. If the checked

 deflections do not meet conditions in step 3, proceed to step 5

 considering that the predictions may be approximate or significantly

 in error.

 5. Obtain pavement layer thicknesses from construction drawings or by

 coring.