Tuesday, July 24, 2018

Restoring UP/Southern Pacific 1926 Tunnel #11

UP (source)
What does it mean to dig "by hand?" It does sound like they dug it out with spade shovels. But that is inconsistent with the photo showing them spraying high-pressure water near the top of the tunnel. I've seen them hose demolition work to control the dust. But shoveling wet dirt does not create dust. So are they using some sort of sluicing operation to remove the dirt? Or maybe they are knocking the dirt of the steel channels they drove in to stabilize the top so that they can then dig out that dirt.

The tunnel...collapsed before crews could finish a routine lining replacement. No one was inside.
Prior to the collapse, crews were finishing the last six feet of a routine tunnel lining replacement when water started flowing in. “As soon you see water, you get out,” Hill said. “Safety protocol is to back out, let it happen, then once it’s safe, start mucking it out. That safety protocol paid off. Everyone was out of the tunnel when it collapsed; no one got hurt.” [UP]
Crews installed metal frames and steel channels to stabilize the tunnel. After 23 days of around-the-clock work, the team completed the project injury-free.
"The tunnel is now hardened with a nearly impenetrable steel and concrete lining, and Union Pacific is working with the National Forest Service to establish a natural slope to prevent future water erosion." [UP]

I wonder how high the mountain is above the tunnel. Given the cost of the labor and materials to fix it, it must be rather high because with modern excavation equipment I thought they would just daylight it.

Is it this one?
Or this one?
If you click the "Satellite link" so that you can see the image without the line, I believe you see a  snowshed on the southeast end.
Actually, there are a lot of tunnels and some serious loop backs on this route. I quit illustrating each tunnel. I did this one because it is particularly long and curved. I wonder if all of these tunnels are through dirt and loose rocks instead of solid rock.

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