It’s summer again, which means that the Midwest and outlying and coastal states are out in force to repair the damage caused by winter potholes and wear-and-tear on local roads.
Before patching or resurfacing, many communities will consult the Pavement Condition Index. Mohamed Shahin, in his book, “Pavement Management for Airports, Roads and Parking Lots” defines PCI as “a numerical rating of the pavement condition that ranges from 0 to 100, with 0 being the worst possible condition and 100 being the best possible condition.” The pavement can be distressed by cracks, construction deficiencies, surface weathering, environmental issues or an amalgamation thereof.
A 2011 report, “Street Condition Ratings: Their Use Among North Carolina Cities” by David Ammons and T. Dwight Brinson, noted that “more than two dozen different systems exist, with labels such as Pavement Condition Index, Pavement Condition Rating, International Roughness Index, Pavement Distress Index, Pavement Serviceability Rating and Surface Distress. Not only that, but they observed that some cities did not rate their pavement at all, citing insufficient staff time or capacity as part of the reason for their decision. Some also mentioned the expense of such ratings.”
However, the Pavement Condition Index is still widely used by local government agencies, airports and other smaller agencies responsible for managing pavements, according to Hari Kalla, P.E., director of the Office of Asset Management, Pavement and Construction of the Federal Highway Administration.
“Its advantage is that the system has great documentation and is relatively low-cost to implement. The disadvantage is that it is labor-intensive for large systems and lacks the sophistication of the larger systems used by state agencies,” he noted.
“Pavement management systems provide decision makers with information about the financial obligations of owning and operating roadways. PCI is one of the methods to quantify existing pavement conditions that can be later used to estimate how long the pavements will last and how much funding will be needed to keep them in satisfactory condition. It also provides agencies with an understanding of how well alternatives, such as preservation programs, will work in the local community.”
Whether alternate methods should be used for evaluating pavement depends on the community.
“What is critical is to capture the most accurate and objective view of actual pavement conditions,” said Kalla. “When properly employed, PCI can do that. There are a number of alternate methods that also work very well, each with its own specific issues, costs and labor requirements.”
In addition, Kalla referred to the FHWA Guidance on Highway Preservation and Maintenance document published Feb. 25 for the following definitions:
PRESERVATION consists of work that is planned and performed to improve or sustain the condition of the transportation facility in a state of good repair. Preservation activities generally do not add capacity or structural value, but do restore the overall condition of the transportation facility.
MAINTENANCE describes work that is performed to maintain the condition of the transportation system or to respond to specific conditions or events that restore the highway system to a functional state of operation. Maintenance is a critical component of an agency’s asset management plan and is comprised of both routine and preventive maintenance.
ROUTINE MAINTENANCE encompasses work that is performed in reaction to an event, season or overall deterioration of the transportation asset. This work requires regular, recurring attention.
PREVENTIVE MAINTENANCE is a cost-effective means of extending the useful life of the federal-aid highway. Some examples of emergency pavement maintenance include tending to washouts, rigid pavement blowups, pumping and water seepage, buckling, freeze-thaw damage and anything that poses a safety hazard.
Other factors affecting pavement performance include subgrade soil, pavement material attributes, moisture and temperature.
Shahin noted that standard practice is to evaluate roads and parking lots with PCI surveys. “The PCI provides a measure of the present condition of the pavement based on the distress observed on the surface of the pavement, which also indicates the structural integrity and surface operational condition — the localized roughness and safety.”
The Kentucky Transportation Cabinet has three asset collection vehicles in its fleet. These vehicles collect data automatically, on an annual basis, of the interstate and NHS routes; and on a two-year cycle for all non-NHS routes. Average yearly collection, according to the website, is 35,000 lane miles. This data collection includes automated pavement distress, rutting, cross slope, IRI, faulting, curve and grade, GPS data and roadway images. In addition to network testing, the KYTC also performs IRI acceptance testing for new construction.
Kentucky, however, is not a PCI user, according to Tracy Nowaczyk, operations and pavement management branch manager.
“Kentucky does not use PCI as defined by ASTM methodology. Kentucky uses a pavement priority score that was developed by the University of Louisville to assign a single score to pavement sections and prioritize pavement projects,” said Nowaczyk.
“The pavement priority score combines pavement metrics such as cracking distress measures, roughness, rutting and faulting with individual weights.”
As far as size of a city making a difference in PCI’s usefulness, Nowaczyk continued, “Any region faced with deteriorating pavement networks and restricted funding would benefit from a system of prioritization based on objective pavement condition data and a defined process to select and prioritize projects.”