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TRANSPORTATION RESEARCH BOARD 2011 EXECUTIVE COMMITTEE*Ībbreviations used without definition in TRB Publications: AAAE AASHO AASHTO ACI–NA ACRP ADA APTA ASCE ASME ASTM ATA ATA CTAA CTBSSP DHS DOE EPA FAA FHWA FMCSA FRA FTA IEEE ISTEA ITE NASA NASAO NCFRP NCHRP NHTSA NTSB SAE SAFETY-LU NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Trade-Off Considerations in Highway Geometric Design t b = T sb - t s92+ pages Perfect Bind with SPINE COPY = 14 pts From this we can find out the value of t b. Repeat the above procedure again, from the CBR value of base course and from traffic intensity value read the value of thickness of pavement which is above the base course (t s). Therefore, thickness of sub base course t sb =T – Tsb Calculation of base course thickness (t b): Which is highlighted by circle in the below fig. Now, from the given CBR value of subgrade soil read the total thickness (T) with respect to selected curve.īy using the above chart, for give CBR value of sub base course material and for traffic intensity value read the thickness of pavement which is above the soil sub base. In this step, firstly for the given value of traffic intensity select appropriate curve from classification table which is shown in the below chart. Based on this we will find out the layers thicknesses. In this method, the chart contains several curves (A, B, C, D, E, F, and G) which represents the different levels of traffic intensities. Therefore all the values of pavement are known and cross section of pavement is as follows.ĬBR method recommended by IRC (Indian road congress):

Similar to the above procedure, from the CBR value of base course and wheel load read the value of thickness of pavement which is above the base course (t s). Therefore, thickness of sub base course t sb =T – Tsb Calculation of base course thickness (t b ): Wheel load is classified into three groups based on traffic conditions.įlexible Pavement Design Procedure: Calculation of total thickness (T):įrom the below chart for given CBR value of soil subgrade and Wheel load value select appropriate thick curve value of “combined thickness of surface, base and sub-base line” which will give the total thickness of pavement.Ĭalculation of sub base course thickness (t sb):īy using the above chart, for give CBR value of sub base course material and for wheel load read the thickness of pavement which is above the soil sub base.