Cascade Tunnel an Engineering Mistake (?)

[beaulieu]

In a discussion on the Trainorders forum, a former Chief Dispatcher for BN who was in charge of the line through the Cascade Tunnel said that the Tunnel Ventilation issue being a limiting factor on line capacity is a bunch of Horsefeathers. If it was a problem, then adding a mid-tunnel door like the Mount MacDonald Tunnel on CP has would solve the problem at a reasonable cost. The problem is the gradient through the tunnel and the distance between the sidings at either end. If the freight trains were the length of the Empire Builder and powered the same amount, you could operate a lot more trains per day through the tunnel. Where some problems with ventilating occur, they happen because the Dispatcher doesn't begin the ventilation promptly. This can happen because the Dispatcher is distracted by things happening elsewhere on his district, or if he (she) just isn't paying attention. And then there is the need for MOW to have track time, not just on the tunnel itself, but also anywhere between Skykomish and Wenatchee.

[Bruce Kelly]

The story begins falling apart with the sentence, "Because the sun directly strikes south-facing  peaks, they're susceptible to avalanches in the spring." Every study I have read on avalanches from the Rockies to the Cascades concludes that the main causes (to describe here in the most simple of terms) are periods of heavy snowfall followed by rain and/or sudden warming, often after cycles in which layers of ice or crusted snow have formed between larger snow slabs. None of these studies have ever mentioned exposure to sunlight. In fact, history says the 1910 Wellington avalanche cited in the story happened during rainfall, with thunder reported as a possible trigger.

The worst avalanche zone on the Stevens Pass route, for the railroad anyway, was the stretch between Wellington and Scenic on the loops which were abandoned in 1929. But the route proposed in this story would not protect trains from avalanches, as the author claims. Between Scenic and Wellington alone, his proposed route would take trains through 13 documented avalanche chutes, half of which are rated as "high" to "frequent" for slide potential. To say nothing of the large slide zone west of Deception Creek.

Before claiming the old Cascade Tunnel would afford BNSF greater capacity than the current Cascade Tunnel, there needs to be a more thorough comparison of the two. (I trust RWM and PDN will crunch the numbers against speed, emissions, etc., and give us the results.)

Old Cascade Tunnel: 2.63 miles long, 1.75 percent grade eastward, 3375-foot summit at east end.

New Cascade Tunnel: 7.79 miles long, 1.57 percent grade eastward, 2883-foot summit at east end.

20 minutes to clear fumes from new tunnel. How long to clear from old tunnel?

It seems to me the biggest shortcoming of both tunnels is their steep grade within, resulting in more exhaust build-up than should have been for a summit tunnel. Closest counterparts at Snoqualmie Pass and Stampede Pass have minimal grades within.

The story's comparison to Donner is like comparing apples to avacados. Donner in its day had two main lines over/through the summit. The most cursory look at their topography shows how CP (later SP) was able to follow ridgelines and hilltops, avoiding most avalanche areas, whereas GN through the Cascades had few such options.

 And please don't pluralize Sierra Nevada with an "s". Call them the Sierras, maybe.

[zardoz]

Paul_D_North_Jr

Also, as an isolated electric operation, the electrics would have to be added on and taken off before and after going through the tunnel; otherwise, as a run-through the motive power districts and utilization would get all messed up.  On the other hand, as compared to the current wait for the bore to clear out, maybe that delay would be acceptable, or no worse.  Also, if a train has to wait for either an opposing or preceding move to clear through the tunnel, the connect and disconnect operations might not take all that much additional time anyway.

Much would depend on the weather. If it is above 50 degrees, then yes, the add-ons would usually not take much extra time.  However, if the train has just bashed through numerous deck-high or greater snowdrifts and the locomotives are encrusted with packed snow and ice, and/or if the temperature has dropped well below freezing, then the add-on/take-off operation would frequently be unworkable.

[Paul_D_North_Jr]

Murphy Siding

  [snip]  Related subject:  We keep discussing electrification.  Wouldn't the Cascade Tunnel be a prime candidate for it? 

Yes, from a 'need' perspective; but probably not from any other.

Clearances there are so close with a double-stack that overhead catenary is not possible to install.  See the photo at:

 http://www.flickr.com/photos/9131426@N06/4141586631/ 

However, I wonder if a 600 volt 3rd rail installation could be fit in at the lower side of the tunnel - see the photos at:

http://media-2.web.britannica.com/eb-media/45/124945-004-B7B379EA.jpg and

 http://www.railpictures.net/viewphoto.php?id=282858 

as in the New York City operations.  That could power either dedicated electrics for there only, or pick-up shoes on a western mountain version of the old New Haven dual-power FL-9's and whatever the Amtrak/ Metro-North current replacement is called - I believe it is P32AC-DM - see:

http://en.wikipedia.org/wiki/GE_Genesis

http://en.wikipedia.org/wiki/File:MNR_P32_Tremont.JPG and

 http://www.railpictures.net/viewphoto.php?id=265278 

Also, as an isolated electric operation, the electrics would have to be added on and taken off before and after going through the tunnel; otherwise, as a run-through the motive power districts and utilization would get all messed up.  On the other hand, as compared to the current wait for the bore to clear out, maybe that delay would be acceptable, or no worse.  Also, if a train has to wait for either an opposing or preceding move to clear through the tunnel, the connect and disconnect operations might not take all that much additional time anyway.

As much as I like electrification, I also have to wonder if this problem cannot be solved more economically by installing a souped-up ventilating system, and/or drilling a couple of ventilating shafts down from the top of the mountain, and installing high-power exhaust fans.

- Paul North.

 

[schlimm]

 I wouldn't assume all the decisions made by corporate are the right ones for their company, much less society.  The classic economist, Adam Smith, is always held up as the paragon of the virtues ofmarket capitalism:  "The Invisible Hand."   Turns out he is often misquoted and thought decisions by big capitalists were often quite wrong for the public.

Today's Most Mischievous Misquotation - 98.03

[creepycrank]

The new Cascade tunnel was electrified but GN couldn't ride of all that equipment fast enough after system wide dieselization. There are a couple of Columbia River hydro dams near Wenatchee at the bottom of the hill too. The electricity must have cost next to nothing. I've never seen an adequate explanation why this was done.

[Murphy Siding]

     That's the title of an article in the current (Jan. 2010) Trains Magazine.  In a nutshell, the author, who worked for GN/BN/BNSF from 1963 to 1999, says that GN made a mistake in 1929 with its new tunnel and alignment.  He feels, that GN could have kept the old tunnel, and moved the west approach to the south side of the valley, and (?) stretch out the rise on the west side.  I'm skeptical.  His propsal seems to make sense to a know-nothing like me.  

      What I can't agree with, is his idea that GN goofed,  when the answer was so much simpler and less expensive.  He suggests that Ralph Budd pushed it through to have a showpiece tunnel engineering project on his railroad.  I believe, that even back in 1929, railroads had engineering and finance people on board who could help make the right decision.  Did they miss something?

    Related subject:  We keep discussing electrification.  Wouldn't the Cascade Tunnel be a prime candidate for it?