Andy Tullis / The Bulletin file photoEmployees of Deschutes County Road Department, chip seal the surface of NE 17th St near the intersection of NE Wilcox Ave in Terrebonne in June.

The high cost of asphalt, a petroleum-based material used to construct and maintain roads, is one of the reasons the costs for street maintenance in the city of Bend and throughout Deschutes County have skyrocketed over the last several years.

Bend officials are looking at $80 million in repairs to maintain a healthier overall road system. The deficit has spurred talk of a local gas tax, which city councilors plan to put on the March ballot for residents to decide.

The Bend and county governments gauge costs by lane mile. Each lane is 12 feet wide. Paving companies are contracted by the city and county to complete the work.

The cost of placing new asphalt over existing asphalt for a maintenance overlay has nearly quadrupled for the city since 2004, according to David Abbas, the city’s streets and operations director.

“What we’ve seen as the main challenge is the cost of doing business far outpaces the revenues,” said Abbas.

Abbas said he recalls an asphalt overlay contract costing $22,000 per lane mile in 2004. A recent 2015 contract cost the city $84,000 per lane mile.

One of the biggest revenue factors is the city’s reliance on the state gas tax, which is 30 cents per gallon. The city’s street department receives about 48 percent of its budget from the state tax.

“It’s a good portion of our budget, and every penny pretty much goes to maintenance,” said Abbas.

The revenue has been stagnant if not declining because of more fuel-efficient vehicles and residents in larger Oregon cities using better public transit options, Abbas noted.

The Deschutes County road department has also been hit with the high cost of asphalt when trying to maintain its road system, which encompasses about 900 miles.

Chris Doty, the county road department director, said an asphalt overlay per lane mile in 2002 cost the county $34,500. In 2015, that same amount of road is costing the county $77,000.

Doty said demand for asphalt was high leading up to the Great Recession in 2007 and translated into high costs. But those costs haven’t dropped in correlation with falling oil prices.

“We’ve seen oil come down quite a bit, but asphalt hasn’t come down much at all,” said Doty.

Part of the reason, he said, is asphalt for paving roads requires a heavier crude oil, which is extracted primarily from the Middle East. Shale oil retrieved by hydraulic fracturing, or “fracking,” in the United States is much lighter and not useful for asphalt, Doty said.

“It doesn’t produce the same type of paving oil,” he said.

The city has 840 lane miles to maintain. About 72 percent of city roads are local residential streets, according to Abbas.

The current grade for city streets is about 68 out of 100 based on the pavement condition index, a federal assessment tool used to judge the condition of city streets.

Abbas said the goal is to get the city’s index score up to the high 70s or low 80s. If the number continues to drop, it will end up costing the city more in the long run to rehabilitate the roads, he said.

— Reporter: 541-617-7820, tshorack@bendbulletin.com