The design procedure recommended by the American Association of State Highway and Transportation Officials Important Variables used in AASHTO Design Method
1- Pavement Serviceability Index
2- Reliability
3- Standard Deviation
4- Resilient Modulus
5- Drainage Coefficient
6- Layer Coefficient
7- Equivalent Single Axle Load
8- Structural Number
Pavement Serviceability Index (ΔPSI) Serviceability: the ability at time of observation of a pavement to serve traffic (autos and trucks); which use the facility. Based upon Present Serviceability Rating (PSR) Subjective rating by individual/panel Initial/post-construction Various time after construction 3. 4. PSR < ~2.5: Unacceptable 0 < PSR < 5 Trend of serviceability with load application measured by (PSI) present serviceability index. ΔPSI (use in the design equation) = Pi - Pt
