Monday, October 23, 2017

Tunnel No. 7

From: "Andy Payne"

... While going through some material I came across a little note that said Tunnel 7 was originally a tunnel, but then the Southern Pacific daylighted it; later found out they needed a snowshed there because of winter. Would like to know when the tunnel was daylighted and when the snowshed was built. ...

—Andy Payne


Anonymous Anonymous said...

From: "Wendell Huffman"

The September 1967 SP Bulletin has an article about enlarging the tunnels. In describing the work of lowering the floor of tunnel no. 6, it states that all other tunnels were enlarged by raising the crowns.

As we know from the profile appended to John Gilliss’s 1869 report of the CPRR tunnels, there was at the greatest depth only about 20 feet of material above tunnel 7, so raising the ceiling would have left only a very thin layer of material above it. I suspect that this thin natural roof was the reason for replacing tunnel 7’s natural roof with the existing concrete roof.

The [Southern Pacific] Bulletin article goes on to say that tunnel 7 was "daylighted with a single, carefully planned blast." And that "It will be re-roofed with pre-cast concrete slabs. As this issue of the Bulletin goes to press, the concrete foundation on which the roof panels will rest is nearing completion."

10/24/2017 11:37 AM  
Blogger Unknown said...

Thank you Wendell!

10/28/2017 8:01 PM  

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