Nine years after it spent $9.7 million to "superpave" a stretch of Interstate 70 through the heart of Washington County, the Pennsylvania Department of Transportation is going to resurface the highway again.

The work covering 10 miles between Kammerer Interchange and the I-79 South Junction is to run from July 13 until October.

This time, PennDOT will spend $11.6 million for milling and paving alone and does not cover a new concrete barrier and other improvements made in 1999.

The contract does include the cost of salvaging about 100,000 tons of existing asphalt which, once milled to a depth of 4 inches, will be stockpiled and recycled to pave about an extra 40 miles of secondary roads in Washington, Westmoreland, Fayette and Greene counties next year.

PennDOT was planning to pave the same stretch of I-70 about two or three years from now, but engineers determined they couldn't wait much longer.

"The pavement has been there since the 1950s and 1960s and has gone through many paving cycles," PennDOT District 12 Executive Joe Szczur said. "Starting in January, our folks started noticing severe deterioration along the joints and edges. Then we started to see the pavement delaminate. We became concerned that the road wouldn't make it through another winter."

The stretch of limited-access highway between Washington and Greensburg was conceived as an economic development stimulus project in the 1950s. Although it was never built to interstate standards and it was designed for far less truck traffic at a time when the maximum gross vehicle weight was 28 tons, the highway was nonetheless incorporated into the interstate program.

"It's an old, aging, very functionally deficient corridor," Mr. Szczur said. "That's why we have to mill so deep, because of the stress and the strain on the overall road structure."

About 35,000 vehicles a day travel the 10-mile stretch, many of them large trucks on the way to and from the New Stanton Interchange of the Pennsylvania Turnpike. The traffic volume swells in summer because of vacation travel.

Most of the work will be done on weekday nights and weekends because of the heavy use. The contractor, Lindy Paving, of New Castle, must have all four lanes open by 8 a.m. or be penalized $20,300 per incident.

PennDOT has another penalty stipulation of $10,150 every time lanes are closed between 8 a.m. and 8 p.m. Sunday. Because of how it plans to sequence the work, Lindy apparently figured it's cheaper to pay the penalty and keep working on as many as four Sundays, starting July 13.

"We were fortunate to get the money to do this work," Mr. Szczur said. "We were able to get some interstate maintenance funds in advance," whereby 80 percent of the cost will come from the Federal Highway Administration.

Work is tentatively scheduled to start in the eastbound direction. At some points, lanes will be restricted in both directions, leaving only one lane open for travel.

At the same time, PennDOT will replace reflectors that have fallen off or been dislodged from the concrete median barrier, an aid to nighttime and bad-weather driving.

"A lot are missing," Mr. Szczur conceded, "but that's not unusual on I-70 because of the tightness between the travel portion of the road and the barriers, oversized loads, snow removal and other factors."