Preliminary Rockfall Evaluation for the Historic Columbia River Highway State Trail, Segment E

The Historic Columbia River Highway (HCRH) is America’s first scenic highway and was constructed between 1913 and 1922. During the 1940’s and 50’s many sections of the HCRH were removed and/or abandoned due to construction of a route closer to the elevation of the Columbia River, which would eventually become I-84. Since 1987, the Oregon Department of Transportation has been working with stakeholders to restore the HCRH as a bike and pedestrian trail. Segment E includes a 2.7-mile section of the trail approximately 50 miles east of Portland, OR that is currently under design and awaiting additional funding to construct. Segment E is subdivided into seven rockfall reaches, where the trail alignment runs along the base of slopes with slope between 80 and 280 feet. All slopes are composed of flows of the Columbia River Basalt (CRB) Group, exposed by the Missoula Floods of the late Pleistocene and have a history of frequent rockfall activity. Preliminary rockfall evaluations for the seven slopes in Segment E included surface reconnaissance, on-slope (rope-accessed) reconnaissance and geologic mapping, kinematic analysis, rockfall simulations, and development of preliminary rockfall risk reduction measures. Preliminary rockfall risk reduction measures were required to meet specific rock retainment criteria for the trail and I-84 while limiting impacts to the aesthetic qualities of the Columbia River Gorge. This paper discusses the preliminary rockfall evaluations for all seven slopes, but focuses on the design challenges encountered at two specific slopes within Segment E.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References; Tables;
  • Pagination: 20p
  • Monograph Title: Proceedings of the 70th Highway Geology Symposium (HGS 2019)

Subject/Index Terms

Filing Info

  • Accession Number: 01735579
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 2 2020 9:42AM