ForConstructionPros.com

It wasn't the size of the 11,000 ton asphalt project that made paving the Eisenhower-Johnson Memorial Tunnel difficult. It was the myriad details and obstacles with this unique application that posed the challenges. From the tunnels' low clearance and pavement's specified mix design to the weather and trucking issues, Pavetec Inc., of Silverthorne, CO adapted well to the many twists and turns it faced.

Simply the altitude and ambient conditions of the tunnels, located just outside of Denver, made for difficult paving. Perched at more than 11,000 feet above sea level, the two, 1.7-mile long lanes of the westbound and eastbound bores are the highest vehicular tunnels in the world. "When paving at this height, you have to make sure your equipment is in top operating condition," says Mitch Olson, project coordinator for Pavetec.

Steep seven percent grade approaches and an average snowfall of 312 inches between November and April significantly wreak havoc on the pavement's surface. "When the snow flies in Colorado, the tire chains are put on," says Alan Adams, president of Pavetec. "Abrasion from the chains really affects the service life of the road."

The last complete overlay of the tunnel roads was in 1997, less than 10 years ago. "We design the surface for a 10-year life, but in this environment — heavy truck traffic, weather, salt and chains — we are satisfied with a seven- or eight-year life," explains Ina Zisman, resident engineer for the Colorado Department of Transportation (CDOT).

Low clearance

The tunnel itself forced the contractor to alter typical paving practices. A low, 15-foot clearance and maximum truck height of 13 feet 6 inches to compensate for message boards and signs hanging from the ceiling eliminated the prospect of using end-dump trucks. "We secured live-bottom trucks for this project," says Rusty Evans, transportation manager for Pavetec.