The fight for U.S. 41: It's man vs. mountain, and the mountain is winning

photo A northbound car on U.S. Highway 41 encounters uneven pavement as Aetna Mountain continues to push the road toward the Tennessee River in Marion County. The pavement breakdown is 10 miles from Interstate 24 at Lookout Valley.

SOIL NAILING: HOW IT WORKSSoil nailing is an on-site soil reinforcement technique in which metal tubes are put in the ground at intervals of three to six feet to increase the strength of the soil beneath the roadbed. As the bars are being drilled, grout is inserted into the hole to make sure the soil nail stays put. Solid bars are usually installed into pre-drilled holes and then grouted into place using a separate grout line, whereas hollow bars may be drilled and grouted simultaneously by the use of a sacrificial drill bit and by pumping grout down the hollow bar as drilling progresses.