(
Bridge Hunter;
Satellite, North (Railroad East) Portal and ventilation equipment)
This tunnel was paid for by the US Army Corps of Engineering because their
Libby Dam submerged Great Northern's route along the Kootenay [also spelled Kootenai] River. The Feb 2021 issue of
Trains has an article about the tunnel. At 7.1 miles, this tunnel is second in the US to the
7.8 mile Cascade Tunnel. (The
Moffat Tunnel is 6.21 miles long.)
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Loco Steve Flickr via Bridge Hunter, License: Creative Commons Attribution (CC BY)
This is the south end (west end on the railroad) of BNSF Railway's Flathead Tunnel. It is the third-longest railroad tunnel in North America, and second longest in the United States, measuring 7 miles in length. |
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Loco Steve commented on his Flickr photo
This it the other end as we exit... |
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Great Northern Railway Historical Society posted
This date in Great Northern Railway History: November 7th 1970:
The Flathead Tunnel opens.
Cole Allen: On occasion, I do wonder - why did GN have a goat on their logo?
Dave Hahn: Cole Allen http://www.gngoat.org/rocky.htm |
The ventilation system can clear the tunnel in 10 minutes after a westbound train goes through and 20-30 minutes after an east bound train passes. [spwolfmtn comment in
TrainOrders] As part of an improvement effort in 2018, BNSF installed a 2,000-kilowatt backup generator to maintain normal power levels. Before that upgrade, it could take twice as long to flush the tunnel. The tunnel handles about 50 freight and 2 Amtrak Empire Builder trains each day. [
FlatheadBeacon]
The 70 [7, not 70] mile Flathead Tunnel, located in the central Salish Mountains of northwestern Montana, was constructed between 1966 and 1969. With the contract awarded April 19. 1966, drill and blast tunnel excavation began September 30, 1966, and was completed June 21, 1968, in 488 tunnel-driving days. Peak advance was 66 feet per day. On June 27, 1969, all tunnel concrete lining was completed. Average wall and arch concrete placing rates exceeded 1,700 cubic yards daily, with nearly half of the concrete placed during a severe winter season. Major cost savings in concrete tunnel lining were achieved through a value engineering clause in the contract. Achieving consistent results and high rates of placement in concrete lining ranked equal to ground control in overall tunnel problems. Ground control problems exceeded expectations and were of continual concern throughout excavation. One support collapse in the tunnel and one portal slide condition developed during construction. Critical surface geologic exposures were largely obscured; only a portion could be accurately projected underground. An instrumentation program to gather basic data on rock deformation near the heading face for support purposes was a pioneering effort. The Flathead Tunnel was placed in service on November 7, 1970. [trid]
A comment on a Moffat Tunnel
post:
Stevie Knox: The Flathead tunnel uses a duct that parallels the tunnel to carry compressed air from the east portal to the center of the tunnel thus pushing exhaust gasses out both ends.
They did not use a tunnel boring machine. They drilled, blasted and mucked. But they had a travelling frame that held floors at various levels at the heading.
The travelling frame also had two sets of tracks that allowed empty muck cars to go around loaded muck cars near the heading.
Even though they installed steel supports after mucking out the heading, they had problems.
They used cut-and-cover to start the bore.
It looks like they cut quite a ways into the mountain.
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