W Road: Signal Mountain highway in fine shape for its age, engineers say (with video)

W Road: Signal Mountain highway in fine shape for its age, engineers say (with video)

May 4th, 2013 by Louie Brogdon in Local Regional News

A crew with GeoStabilization International works to prepare the W Road for a predicted rainy weekend. The road is closed to all uses until further notice.

A crew with GeoStabilization International works to prepare...

Photo by Tim Barber /Times Free Press.

Even though about 250 feet of the W Road have tumbled down the side of Signal Mountain, engineers say the 120-year-old road is in pretty fine shape.

"The last major construction of this scale on the W Road was in 1892," Hamilton County Director of Engineering John Agan said Friday while standing in front of a 100-foot span that was washed out by heavy rain last week.

Engineers have been working on the historic road since early April, when large stress cracks appeared on a newly paved portion. The road was closed. Two segments of the road were partially excavated, leaving gaps, but Mother Nature cleared the rest.

Agan said given the age of the road -- which was built with horse-drawn wagons in mind -- it's in relatively good condition despite being closed for emergency repairs.

"I don't know if there was any expectation [by the road's builders] of vehicle traffic or this volume," Agan said.

Modern roads typically are designed to last 75 years, according to Nate Beard, regional director of GeoStabilization International, the company completing the repairs. But the W Road has outlasted that by nearly half a century.

Beard said he was especially surprised by the craftsmanship of the original rock wall that supports the road.

Initially, Beard said he expected to reinforce parts of the wall, but upon closer examination, there was no need.

"It's 6 feet wide at the base. We drilled into it [to test the wall's stability] and it didn't even unravel. It's solid," Beard said.

The road washed out, he said, because of a number of "voids" found in the earth beneath it. Since the road is so old, there's no way to tell whether the voids were caused by drainage, geographic settling or road pressure, Beard said.

"The only thing we can be sure of is before we leave here, all of these voids will be stabilized and filled," Beard said.

Two sections of road have been cleared so Beard's company can rebuild them using stabilizing rods and soil anchors. On Friday, workers cleared more earth away from the work sites in expectation of more rain this weekend.

Despite weather setbacks, the road still is slated to be in use in nine weeks, Beard said Friday.

Agan said the county will continue to monitor other portions of the road, but the two segments being repaired are the only serious problem areas.

In the meantime, Agan is urging residents to stay off the W Road -- even pedestrians and cyclists. Until the road is repaired completely, it is not entirely stable.

"We'd much rather have this inconvenience than see a catastrophic failure," Agan said.