AASHTO Journal, 4 March 2016
Several states battled rock slides in recent weeks, sometimes after rains or snow melt saturated and destabilized area slopes. The incidents blocked major roadways and left state departments of transportation facing steep repair costs while drivers take long detours.
The Tennessee DOT closed part of north-south Interstate 75 Feb. 26 when boulders came down a hillside near Pioneer, about 35 miles north of Knoxville. Reports said the detour put long lines of backed-up traffic on local mountain roads.
Idaho slide aftermath.TDOT on Feb. 29 awarded a $2.9 million emergency contract to remove the debris, stabilize the slope and repair damage to I-75, but the work will take a while before the lanes begin to reopen in phases.
“The contract also stipulates the southbound lanes of I-75 will be reopened within 14 days and one lane on the northbound side will be reopened within 21 days,” TDOT said. “The entire repair project is scheduled to be complete on or before April 15.
A Feb. 18 landslide along Idaho’s SH 14 for a while cut off the small town of Elk City, until the Forest Service cleared one of its roads of snow to serve as a detour. An Idaho Transportation Department worker was on the scene for part of the slide, and captured the dramatic footage shown below.
Gov. Butch Otter issued a state disaster declaration so the event could qualify for the Federal Highway Administration’s emergency relief funding, saying the debris was up to 60 feet deep and covered 500 feet of roadway.
News reports said it would cost $1.5 million to clear. The FHWA on Feb. 29 made $500,000 available to the ITD in “quick release” funds from its emergency relief account.
That same day the FHWA provided the Colorado DOT with $1 million to help pay the costs of clearing and repairing damage to I-70 from a major rock slide Feb. 15.
The FHWA said CDOT closed I-70 in both directions immediately afterward, then began efforts to stabilize the slope, install fencing along the barrier walls and remove damaged walls and guardrails.
On a daily average, the FHWA said, about 17,000 drivers use that route through Glenwood Canyon, including an estimated 2,100 trucks. The interstate closure required them to detour through Steamboat Springs about 150 miles away.
CDOT was able to restore two-way traffic through the canyon on Feb. 25, but as recently as March 3 it was interrupting road traffic to allow for helicopter operations there to hang “rockfall” netting.
Here is the ITD video of the Idaho slide.
