Little River Road Rockfall Mitigation, Glide, Oregon
A 900-foot segment of Little River Road, at MP 24.6 east of Glide, Oregon, has a history of rockfall activity from a 150-foot-tall rock cut slope that's adjacent to the road. The rockfall causes both a safety risk to the traveling public and increased maintenance efforts for Douglas County engineering & maintenance personnel. This section of Little River Road was blocked by a large rockfall event in 2012 that contained rock blocks up to 20 feet in size, damaging the pavement surface and destroying segments of the guardrail. Portions of one travel-lane remained closed for eight years until construction was completed in 2020. Another large-scale rockfall event occurred in June 2017, necessitating the permanent closure of one-lane of the roadway. 

In September 2017, CCI-LT was retained by the Western Federal Lands Highway Division (WFLHD) to provide a preliminary geotechnical design report, 30% conceptual level mitigation plans, and an engineer’s estimate to reduce the risk of rockfall entering the roadway. The Unstable Slope Management Program (USMP) developed by CCI-LT was used to rate the slope and identify the highest rated slope segments.

Project Highlights
In November 2017, another slope failure occurred, this time 10 to 15 cubic yards of rock debris less than 2-feet in diameter impacted the one outboard travel-lane. CCI-LT quickly mobilized to the site to perform an emergency response reconnaissance using rope access techniques. Our team assessed the rockfall hazards and provided interim rockfall mitigation measures to keep the road open. Our recommendations included removal of hazard trees, slope scaling, and installation of a concrete barrier with a 6-foot-tall fence extension along a 200-foot-long section of the roadway.
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WFLHD subsequently retained our team to provide final design and development of PS&E for rockfall stabilization and protection measures. We also assisted WFLHD with engineering support during construction. Mitigation measures included 1,600 individual scaling hours, 7,800 linear feet of rock bolt and dowel installations (up to 35 feet in length), 3,000 linear feet of unlined drain holes, 59,200 square feet of draped mesh, and 29,700 square feet of 15-foot-tall mid-slope attenuator fencing. Our rope access team worked on the slope alongside the contractor to direct and test all the installed mitigation measures. 

Crews installing draped mesh to control the descent of rockfall and prevent it from reaching the roadway.

Owner: Western Federal Lands Highway Division
​More Information: KPIC: Little River Rock Slide An Unwelcome Surprise

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