A one-year-old pilot project involving local and state agencies that recycles tear-off shingles for use in hot mix asphalt for road paving is showing promise, according to project participants.

The Shingles in Paving Demonstration Project is the first in the state to use recycled asphalt shingles to pave a public road. Eleven other states already use recycled asphalt shingles in asphalt pavements.

Every year, an estimated 23,000 tons of tear-off asphalt shingles from roofing projects in King County go to a landfill. Using them could reduce the costs of paving due to the high quantity of oil in the shingles. By re-capturing the oil, less new oil needs to be purchased.

The project is a collaboration between King County Solid Waste Division’s LinkUp Program, King County Road Services Division, WSDOT and Seattle Public Utilities.

In September 2009, a 2-mi-long stretch of Southeast 416th Street was overlaid with a 2-in.-thick layer of asphalt paving materials, in test sections with and without recycled asphalt shingles.

Staff from King County and the WSDOT recently surveyed the test sections and found no difference in performance.

The county will continue to monitor the structural performance through 2012, at which time it will consider recommendations for the continued use of recycled asphalt shingles on public roadways.