Traffic Load Analysis, ESAL + Truck Factor & Asphalt Institute
This is the role of the Pavement Engineer and involves determining the loading on the road to be carried forward to the Pavement Design. The role of the pavement engineer is to provide an adequate thickness of pavement to carry the expected loads without deterioration of the network during the design life.
The estimated or projected magnitude and occurrence of the various traffic loading are converted to the total number of passes of equivalent standard axle loading (ESAL), usually the equivalent 80KN (18kips) single axle load.
The total no. of ESAL is used as the traffic loading input for design of pavement structure.
Determination of cumulative equivalent standard Axle (Road Note 31).
The steps are as follows;
Total volume of traffic expected during the design period
Estimate the percentage of total trick traffic expected to use the design lane, the design lane is the lane expected to receive the most sever service.
Multiplying number of axles in each weight class, by an appropriate load eq factors.
Summing for the various weight classes dividing the sum by total no of vehicles involved.