Residual

Residual Design Life — FWD Flowchart & Quick Tool

Interactive flowchart to visualize steps + a calculator to estimate remaining service life from FWD data (fatigue & rutting)

Process Flowchart

Click a node

Node details & equations appear here. Use the calculator tab below to try sample computations.

Select a flowchart block to see: purpose, required inputs, typical equations, and recommended references (IRC / M-E formulas).

View Overview Calculator Equations Quick Reference

Quick Calculator

Enter your in-situ moduli / strains & traffic to estimate residual life (simple M-E approach).

Asphalt Modulus E_a (MPa)

Base Modulus E_b (MPa)

Subgrade Modulus E_s (MPa)

Tensile Strain ε_t (microstrain)

Compressive Strain ε_c (microstrain)

Past ESALs (million)

Annual ESALs (million/yr)

Growth Rate (%/yr)

Allowable load repetitions (est.)

Fatigue N_f (million)

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Based on tensile strain

Rutting N_r (million)

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Based on compressive strain

Remaining ESALs (million)

—

Min(Nf, Nr) − Past ESALs

Residual Design Life (years)

—

Remaining ESALs ÷ Annual ESALs

Equations & notes (click)

This calculator uses the following simplified M-E forms (user-specified constants below can be edited in script):

Fatigue: Nf = A_f * (1/εt)^B_f * (1/Ea)^C_f Rutting: Nr = A_r * (1/εc)^B_r Note: ε are in microstrain; N are in millions of axle repetitions. Constants A_f, B_f, C_f, A_r, B_r are adjustable in the code for calibration.

Built for quick assessment — For final design, run full M-E pavement software and professional judgement.