‘Big Slow Movers’ plague Cowee Mountain route
It’s easy to spot the unstable embankments as you drive over Cowee Mountain between Macon and Jackson counties.
Rocks and dirt slowly tumble from the mountain onto the shoulder of U.S. 441, and on occasion, into the roadway. Some of the slides push up under the road, causing the pavement to rise up and make the drive bumpy. While these visuals may cause some concern for drivers, the North Carolina Department of Transportation Geological Unit is aware of these trouble areas and keeps a close eye on the mountain’s movement.
One slide area in particular — located on the right-hand side heading down the mountain on the Macon County side — has been very visible lately due to heavy rains throughout the winter months along with a constant freezing and thawing pattern.
Jack Morgan, planning director for Macon County, said that one area as you come around the last deep curve on U.S. 441 was classified by DOT as a BSM — Big Slow Mover — several years ago when the division mapped out all the slide areas in Macon County.
“BSM stands for Big Slow Mover, and is an area recognized that is not small and is constantly moving but very slowly,” Morgan said. “The DOT monitors this location, occasionally taking correct measures as needed, and would be responsible for any cleanup or repair cause by movement of this mass.”
While the DOT said it is aware of that location, District Engineer Wesley Grindstaff said the area is not currently being monitored on an ongoing basis by the DOT’s geological unit. He said the rock embankment on this particular area was stable on a global scale and the broad shoulder on the road provides plenty of space to contain debris coming off the mountain from smaller slides.
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“This shallow rock slide was likely a result of extremely wet winter combined with the effects of freezing and thawing,” Grindstaff said.
There are other slide areas along U.S. 441 where monitoring and deep rotational failures are taking place. Grindstaff said these areas show up as humps or bumps mostly in the roadway shoulders. Dealing with these kinds of problems has been commonplace since the roadway was completed in May of 1980.
“These deep failures act as if a giant ice cream scoop was being used in the embankments above the roadway,” he said.
The most obvious location is near the intersection with Watauga Road where maintenance crews recently removed a large mass of material that had heaved up in the shoulder and outside the travel lane. Because of this particular failure, NCDOT had to purchase additional right-of-way and a house structure in the early 1980s after acceptance of the highway project.
“These failures are slow-moving, not sudden and catastrophic, and therefore pose little risk to roadway users,” Grindstaff said. “The best fix is simply to remove the heaved material from the shoulders every few years or as needed. These types of situations occur where complicated and unusual geology exist — particularly in silty soils with a high mica content.”
The DOT is also monitoring an area just below the runaway truck ramp heading southbound on the Macon County side, another on the west side of Macon County near Winding Stair Gap and one more on the Jackson County side of the mountain.
