TRN-24

Pavement condition rating

PCR = 100 − wr ur − wc uc − wi IRI. A linear distress deduction from 100.

Reading speed

PavementPCR

Governing equation

\mathrm{PCR}=100-w_r u_r-w_c u_c-w_I\,\mathrm{IRI}

$IRI \in \left[0.5, 8\right]$

where

u_r: Rut depth (mm)
u_c: Cracked area (%)
IRI: IRI (m/km)
w_r: Rut weight (1/mm)
w_c: Crack weight (1/%)
w_I: IRI weight (km/m)
PCR: Condition rating (—)

The figure, part by part

Each numbered marker wears the color of its card. Hover a card to light the marker. Tap a marker to jump to that card. The slider walks a red point along the curve; Animate drawing traces it like a pen.

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①

Governing law — red

\mathrm{PCR}=100-w_r u_r-w_c u_c-w_I\,\mathrm{IRI}

$IRI \in \left[0.5, 8\right]$

$IRI = 0.5$ $PCR = 84.4$

Along the curve

②

Domain of the variable — blue

IRI_{\min} = 0.5,\quad IRI_{\max} = 8

$IRI \in \left[0.5, 8\right]$

$IRI = 0.5$ $IRI = 0.5$

Along the curve

③

Response curve — green

\mathrm{PCR}=100-w_r u_r-w_c u_c-w_I\,\mathrm{IRI}

$IRI \in \left[0.5, 8\right]$

$IRI = 0.5$ $PCR = 84.4$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}PCR}{\mathrm{d}IRI}

$IRI \in \left[0.5, 8\right]$

$IRI = 0.547$ $PCR^{\prime} = -4$

Along the curve

Lecture brief

Historical brief

Highway and traffic theory crystallized with Greenshields’ 1935 speed–density line, then AASHTO stopping sight and equivalent axles. The lab is that operational arithmetic of flow, braking and pavement load. This sheet (TRN-24 — Pavement condition rating) is the form associated with PCR. Working symbols: $u_r$ , $u_c$ , $IRI$ , $w_r$ , $w_c$ , $w_I$ $\rightarrow$ $PCR$ . Condition surveys convert rut, crack and roughness into a 0–100 score used for remaining life and overlay warrants.

Purpose

Purpose: compute

PCR

from

u_r

u_c

IRI

w_r

w_c

w_I

in Transport via

\mathrm{PCR}=100-w_r u_r-w_c u_c-w_I\,\mathrm{IRI}

PCR = 100 − wr ur − wc uc − wi IRI. A linear distress deduction from 100. Use it when a real transport question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

u_r = 8.000\,\mathrm{mm}

u_c = 5.000\,\mathrm{%}

IRI = 2.500\,\mathrm{m/km}

w_r = 1.200\,\mathrm{1/mm}

w_c = 0.800\,\mathrm{1/%}

w_I = 4.000\,\mathrm{km/m}

, the governing relation

\mathrm{PCR}=100-w_r u_r-w_c u_c-w_I\,\mathrm{IRI}

yields

PCR = 76.4\,\mathrm{—}

. Three distress sliders, a falling PCR. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Rut depth u_r8 mmCracked area u_c5 %IRI IRI2.5 m/kmRut weight w_r1.2 1/mmCrack weight w_c0.8 1/%IRI weight w_I4 km/m

Outputs

Condition rating PCR76.4 —

Reading speed

Watch on YouTube

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Narration of this film

Three distress sliders, a falling PCR.

Condition surveys convert rut, crack and roughness into a 0–100 score used for remaining life and overlay warrants.

Reading speed

Watch on YouTube