Hamilton County road workers are back on the W Road this week, working to put a permanent fix on a portion of the road that slowly has been sinking and washing toward the valley below.

"Hopefully this will stop that sinking," said Hamilton County Highway Department Director Harold Austin, describing the new ductile iron pipe the crews will install under the road in coming days. "We closed the road through 4:30 p.m. Thursday."

In mid-October, road crews performed exploratory work on about 50 feet of the bluff-side lane just below the W switchbacks.

Thousands of motorists use the W Road up and down Signal Mountain every day.

After peeling up several inches of pavement and sending a camera robot into the original 1890s storm drain, they put a temporary patch on the road and went to work devising a way to save the road.

The 120-year-old, 24-inch concrete pipe had crumbled after decades of carrying stormwater beneath the road and out through an opening in the rock retaining walls of the historic road. A gaping tear now is allowing the rain swells to scour away earth beneath the road, according to Hamilton County Wastewater Treatment Authority Michael McNair.

In the year since concerned W Road travelers began calling the county about an ever-widening crack, the crescent-shaped sink area has dropped about 10 inches. During that year, road crews have patched the area several times, keeping the road drivable.

Austin said engineers and contractors decided trying to slip a liner into the vintage pipe would not work.

Instead, the original pipe will be replaced.

"We'll be putting it in exactly the same place, because we don't want to cut into the wall again," Austin said.

The upper portion of the rock wall-lined road is on the National Register of Historic Places.

The W originally was part of a pioneer toll road, Anderson Pike, but the rock walls were built by the Works Progress Administration in the 1930s.

Contact Pam Sohn at psohn@timesfreepress.com or 423-757-6346.