If you remember, an effective pavement management program requires three things, the size of the pavement area, the age of the pavement, and a repeatable, objective rating methodology which identifies pavement distress type, severity level, and amount of distress. With this information, we can plot the Figure above. It shows the amount of pavement area within seven age groupings (the blue bars). The gold squares are the average PCI for each group and connected with a thick blue line to help define a trend. Zimmer has data on thousands of pavement management units and the thin blue line with small, black diamond is the average PCI by age group of this data.
The pavement being evaluated for a Zimmer Report is compared to the Zimmer national average. For this example, the slightly subject pavements are performing at or slightly below the national average. The two outliers are the new pavements less than two years old and the greater than 25-year-old pavement. The oldest pavement is likely a Portland cement concrete pad or truck court. The new pavement is probably a simple, thin asphalt concrete overlay where the damage in the original pavement layer has worked up through the overlay.
When combined with a knowledge of the maintenance & rehabilitation techniques used on earlier restoration projects, the engineer can determine an approach to use for future programs.
Figure from Zimmer Consultants.