Supervisors approve application for rubberized paving grant

The Board of Supervisors approved the application for a state grant to use rubberized asphalt concrete for paving on county roads.

The 4-0 vote January 5, with Supervisor Greg Cox in Washington for the National Association of Counties meeting, authorizes the application to the California Integrated Waste Management Board and the acceptance of the grant if offered. If the grant is awarded, the project will return to the supervisors for authorization to advertise and award a construction contract.

In 1993 the State of California banned the disposal of whole tires in landfills, and since then the state has developed programs to increase the recycling of tires. One such program is the rubberized asphalt concrete resurfacing program, which uses recycled tire material.

In addition to the landfill diversion benefits, rubberized asphalt concrete has also shown to have roadway benefits. Although rubberized asphalt concrete is approximately ten percent more expensive than

ordinary asphalt concrete, it has proven to be more durable than normal asphalt concrete.

“What they’re finding is the repaving recurrence is less frequent with rubberized AC than with normal AC,” said Eric Swanson, a senior civil engineer for the Transportation Division of the county’s

Department of Public Works.

The studies in California and Arizona determined that overall costs for a lifecycle of 20 to 30 years were lower with rubberized asphalt concrete.

The County of San Diego has used some rubberized asphalt concrete paving in recent years on a trial basis. The results found that in San Diego County the rubberized paving was feasible not only in terms of maintenance but also for sound reduction. “It has significant positive characteristics on that as well,” Swanson said of the sound reduction of rubberized asphalt concrete.

Rubberized asphalt concrete reduces noise by four to six decibels over the long term. “Usually there’s a great reduction early on,” Swanson said.

That sound reduction is not as significant during the later period of the rubberized paving. “Still there is a net reduction of noise,” Swanson said.

Rubberized asphalt concrete material currently costs between $50 and $60 per ton. “It is more expensive,” Swanson said. “There is a higher up-front cost than with regular AC.”

The competitive grant would offset $2.50 per ton if awarded. The maximum amount of the grant is $50,000, or partial reimbursement for 20,000 tons. Projects must use crumb rubber materials derived from California waste tires and must use at least 2,500 tons of rubberized asphalt concrete.

Department of Public Works staff is identifying road segments where the use of rubberized asphalt concrete will provide optimum benefit; in addition to focusing on roads which are currently in need of repaving the benefit is maximized on roads with high traffic volumes which are close to residential areas.

The supervisors’ action to approve the construction contract process would include a list of targeted road segments. The list of roads and the contract process will likely be brought to the supervisors in Spring 2005.