<< Click to Display Table of Contents >> Navigation:  Pavement Concepts > ESAL

ESAL stands for Equivalent Standard Axle Load. The term is synonymous with E80, which stands for 80 kilo newton equivalent. The purpose of the above is to convert number of axle-loads of various magnitudes into a number of standard axle-loads that have the same damaging effect on the pavement. Standard axle load is an axle load of 80 kN; this corresponds, approximately, to an axle mass of 8.2 t.

 

The conversion formula is:

 

ESAL (= E80) = (A /8.2)b

 

where

 

A      axle load in metric tons

b      damage exponent

 

The value of the damage exponent is usually taken as b = 4.5 for concrete pavements, and b = 4.2 for flexible pavements.

 

One should realize that the mechanistic design implemented in the cncPAVE program is based on the actual damage caused by individual axle loads rather than the number of standard load equivalents. The program evaluates and reports ESALs (E80s) for information purposes only. However, should you wish to design using the E80 method do the following:

 

On the Axle Loads Page, choose an appropriate traffic situation. Look at the value of E80/HV printed at the end of the 3rd line of the graph footnote. If the value correctly reflects your E80 loading, go to the Control Page and Run the process. If not, by trial and error, enter various adjustment factors into the k-factor box above the graph. The graph will be updated as the k-factor value is saved. Check the new value of E80/HV printed below the graph. Repeat the above steps until you get the value that correctly reflects your E80 loading. After this, run the program again.