A Standard of Good Practice
WAC 136-70 requires Washington State Counties to implement a pavement management system in order to be eligible for the County Arterial Preservation Program (CAPP), assuring that paved county arterial roads data is available to evaluate regionally.
What is a Pavement Management System?
Pavement Management System (PMS) is a methodology for maintaining road surfaces by systematically analyzing pavement life cycles and pavement ratings to determine timing of a pavement preservation, as well as the most cost effective pavement rehabilitation type. In addition, a PMS assists in developing pavement rehabilitation budgets that will prevent major road deterioration.
The roadway and pavement information is in the County Road Log, and updated annually as part of the Road Log update process. The Mobility PMS uses the Road Log information directly; counties using another PMS program have a routine to transfer the current Road Log information to their program.
There are three levels of work on pavements:
- Routine maintenance (pothole repair, patching, crack sealing, etc), done on an as-needed basis.
- Preservation or rehabilitation (installing a new wearing surface, a seal coat or overlay), done on a cyclic basis.
- Reconstruction (remove and replace the pavement and base structure), done when the road has failed or needs widening or realigning.
There are three phases in the life of a pavement:
- When the pavement is in good or better condition and does not need a preservation (PSC above 60).
- When a pavement preservation is cost effective (PSC between 60 and 40).
- When the pavement is in such a poor condition that a pavement preservation is no longer cost effective (PSC less than 40), reconstruction is needed.
l or statewide arterial preservation and rehabilitation needs.
Mobility's Pavement Management System - MPMS
The year the pavement reaches the should and must levels is critical. The "should" level is the PSC level where a rehabilitation should be considered. If the PSC is above the should level, there is still life available in the pavement, and rehabilitation is not yet cost effective. If PSC is below the "must" level, the pavement is in such a deteriorated condition that the road should be rebuilt and a surface rehabilitation will not be adequate to restore the road to its original condition. The should and must levels are selected by the user. Typically the should level is a PSC of 60 (representing a 40% drop in quality) and the must level is a PSC of 40.
By knowing when pavement preservation is cost effective, the county can spend their limited pavement preservation funds on the most cost-effective rehabilitations. By properly preserving their pavements, they reduce the need for and cost of routine pavement maintenance.
The results of the PMS program are not the final answer. The PMS results are but one of the items that must be considered during the engineering analysis of the proposed pavement preservation program. Each proposed project needs to be reviewed to make sure it is the right thing to do.
The PMS strategy applied in Mobility Pavement Management System consists of four major parts:
1. Surface Conditions – Recording visible distresses on the pavement surfaces, which are calculated into a Pavement Structural Condition (PSC) score. Alligator Cracking and Patching have the highest deductions. The top 4 core structural pavement defects are – Transverse cracking, Longitudinal cracking, Alligator cracking, and patching. At a minimum, counties are required to rate their Paved Arterial network (Arterial and Collector roads) every two years.
2. Generate Project File - Define a road system as a rational set of projects.
3. When Analysis - Formulate a Pavement Performance Curve to predict the PSC score for each project segment.
4. What Analysis - Define and apply a budget and strategy, comparing the results of multiple iterations to determine the best course of action.
Download the report that describes the four major parts of the MPMS strategy in detail.