# Flexible Pavement Design Structural Number Calculator

The strength of the pavement structure and pavement layers is characterized by a number in engineering is called as the Structural Number (SN). It is a number that says about a pavementâ€™s required structural strength. This online flexible pavement design structural number calculator helps you to calculate the indexing number called SN which is necessary for pavement design.

### Example:

Calculate the flexible pavement structural number given that,

a1=Layer coefficient for asphalt = 8

ta=Asphalt layer thickness = 8

b1=Layer coefficient of base = 7

tb=Base layer thickness = 7

c1=Layer coefficient of sub-base = 5

tsb=Sub-base layer thickness = 6

d1=Layer coefficient of additional layer = 9

tad=Thickness of additional layer = 4

#### Solution:

Flexible Pavement Structural Number (L) = 8 x 8 + 7 x 7 + 5 x 6 + 9 x 4

= 64 + 49 + 30 + 36

= 179