Zimmer Consultants uses the widely accepted Pavement Condition Index (PCI) pavement rating methodology. The PCI was developed by the United States Army Corps of Engineers’ Construction Engineering Research Laboratory under the direction of Dr. Mo Shahin. The original uses were the US Army and Air Force. They use the PCI to determine optional maintenance & rehabilitation programs. In the early 1980’s the American Public Works Association brought the PCI to the public works sector. Zimmer has used the PCI since 1988.
Distress In Asphalt Pavements
During the field condition surveys and validation of the PCI, several questions were commonly asked regarding the identification and measurement of some of the distresses. The answers to these questions are included under the section titles “How to Measure” for each distress.
For convenience, however, items that are frequently referenced are listed below:
- If alligator cracking and rutting occur in the same area, each is recorded separately at its respective severity level.
- If bleeding is counted, polished aggregate is not counted in the same area.
- Bumps and sags are measured in units of linear feet.
- If a crack occurs at the ridge or edge of a bump, the crack and bumps are recorded separately.
- If any distress (including cracking and potholes) is found in a patched area, it is not recorded; its effect on the patch, however, is considered in determining the severity level of the patch.
- A significant amount of polished aggregate should be present before it is counted.
- Potholes are measured by the number of holes having a certain diameter, not in units of square feet.
The above is not intended to be a complete list. To properly measure each distress type, the inspector must be familiar with its individual measurement criteria.
Nineteen distress types for asphalt-surfaced pavements are listed alphabetically.
Ride Quality must be evaluated in order to establish a severity level for the following distress types:
- Railroad Crossing
To determine the effect these distresses have on ride quality, the inspector should use the following severity-level definitions of ride quality:
- L (low). Vehicle vibrations (e.g., from corrugation) are noticeable, but no reduction in speed is necessary for comfort or safety, and/or individual bumps or settlements cause the vehicle to bounce slightly, but create little discomfort.
- M (medium). Vehicle vibrations are significant, and some reduction in speed is necessary for safety and comfort, and/or individual bumps or settlements cause the vehicle to bounce significantly, creating some discomfort.
- H (high). Vehicle vibrations are so excessive that speed must be reduced considerably for safety and comfort, and/or individual bumps or settlements cause the vehicle to bounce excessively, creating substantial discomfort, and/or a safety and/or high potential vehicle damage.
Ride quality is determined by riding in a standard-sized automobile over the pavement section at the posted speed limit. Pavement sections near stop signs should be rated at the normal declarations speed used when approaching the sign.
Distress In Jointed Concrete Pavements
Nineteen distress types for jointed concrete pavements are listed alphabetically. Distress definitions apply to both plain and reinforced jointed concrete pavements, with the exception of linear cracking distress, which is defined separately for plain reinforced jointed concrete.
During the field condition surveys and validation of the PCI, several questions were often asked regarding the identification and counting method of some of the distresses. The answers to these questions are included under the section titled “How to count” for each distress. For convenience, however, items that are frequently referenced are listed below.
- Faulting is counted only at joints. Faulting associated with cracks is not counted separately since faulting is incorporated into the severity-level definitions of cracks. Crack definitions are also in defining corner breaks and divided slabs.
- Joint seal damage is not counted on a slab-by-slab basis. Instead, a severity level is assigned based on the overall condition of the joint seal in the area.
- Cracks in reinforced concrete slabs that are less than 1/8 in. wide are counted as shrinkage cracks. Shrinkage cracks should not be counted to determine if the slab is broken into four or more pieces.
- If the original distress of a patch is more severe than the patch, the original distress is the distress type recorded.
- Low-severity scaling (i.e., crazing) should only be counted if there is evidence that future scaling is likely to occur.
- The severity level of blow-up and railroad distress in jointed concrete pavements is rated according tot he distress’ effect on ride quality.
The above is not intended to be a complete list. To properly measure each distress type, the inspector must be familiar with its individual criteria.