Traffic Index Calculator

Calculate pavement Traffic Index from cumulative ESALs and lane distribution factor, or estimate TI using AADT, truck share, growth, and design life.

TI from ESAL

TI from Traffic Inputs

Enter any 2 values to calculate the missing variable

Number of Cumulative 18‑kip Equivalent Single Axel Loads Over the Design Life of the Pavement Structure

Lane Distribution Factor Preset LDF by Lanes in One Direction (optional) Traffic Index (TI)

Traffic Index Formula

The following two example problems outline the steps and information needed to calculate the Traffic Index.

TI = 9.0*(ESAL * LDF / 10^6) ^ .119

Variables:

TI is the Traffic Index ( )
ESAL is the number of cumulative 18-kip equivalent single axel loads over the design life of the pavement structure
LDF is the lane distribution factor

The following steps outline how to calculate the Traffic Index.

First, determine the number of cumulative 18-kip equivalent single axel loads over the design life of the pavement structure.
Next, determine the lane distribution factor.
Next, gather the formula from above = TI = 9.0*(ESAL * LDF / 10^6) ^ .119.
Finally, calculate the Traffic Index.
After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

number of cumulative 18-kip equivalent single axel loads over the design life of the pavement structure = 35,000,000

lane distribution factor = .75

TI = 9.0*(ESAL * LDF / 10^6) ^ .119 = ?