Twin Tunnels Catchment Structure
From Oregon Hikers Field Guide
- Hikes including this location:
- Mosier Twin Tunnels Hike (TH | <— —> | LOG)
- Weather forecast: NWS/NOAA
- Maps: Oregon Hikers Maps Google Maps
- Latitude, Longitude: 45.68466, -121.42427
- Elevation: 400 feet
Description
In 1995, when the decision was made to reopen the Mosier Twin Tunnels for tourist use, there was immediately a question of safety. The area was always prone to rockfall, but times have changed since the highway was built in the 1920s. If the state was going to bring the public into a rockfall zone in the 1990s, they had to be able to guarantee their safety to a level unknown in 1921.
The tunnels could be shored up with a new lining, but about 700 feet of trail just west of the tunnels was still going to be dangerous. In places, in the 40 odd years since the highway had been closed, over 15 feet of rock rubble had fallen from the cliffs to the road. The first thought was to build a shed that would force the rocks farther over the side. Unfortunately, there's a railroad immediately under the trail, and the Union Pacific wasn't big on the idea of catching rocks.
The solution was to build the catchment structure shown here. The catchment structure is designed to catch rocks, rather than letting them hit the trail or bounce over the side. Above the roof slabs is a level of foam and pea gravel. The structure was designed to handle a rock that weighed 5,000 pounds falling 200 feet. The structure was tinted dark on purpose to help blend in to the rock visually.
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Contributors
- Stevefromdodge (creator)