Timber Road was closed indefinitely between Strassel and Cochran roads after we detected that a slow-moving landslide near the S curves was increasing in activity. Movement, including substantial pavement settlement, created potential for significant damage should the landslide movement continue to intensify.
Local access is allowed outside of the landslide site. Timber Road is closed to all traffic at the landslide site. A long-term road closure plan is in place, including permanent barriers around the landslide site.
It may take up to two years to begin construction on a repair. Due to the severity of the slide, an interim repair may not be possible.
10/17/2023: We have completed an initial geotechnical evaluation and are evaluating repair options.
The work defined the shape, location and movement of the landslide. Using that information, our consultant has developed three possible project concepts to stabilize the landslide. See the project concepts:
A shear key would involve excavating soft earth under the landslide down to the stable ground and replacing it with a stronger rockfill to improve stability. Our consultant developed two shear key concepts:
- Replacing earth under the road and in the downslope embankment
- Replacing earth entirely in the downslope embankment
The Mechanically Stabilized Earth Wall concept would involve excavating the earth directly under the road, down to stable ground. It would be replaced with stronger fill materials supported by a retaining wall on the outer edge of the road.
Each of the options has advantages and disadvantages. Our staff are working to weigh the costs and benefits of the project concepts. Once we decide on a concept, our consultant will complete additional geotechnical and engineering analysis before designing the project. We cannot estimate a construction and reopening timeline until we decide on a project concept and funding source.