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Re: Base tunnels
Author: Dave Smith
Date: 10-29-2007 - 19:33
Ernest H. Robl Wrote:
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>
> The problem with very long tunnels and diesel
> operations (in the U.S.) is, of course,
> ventilation. The longest U.S. rail tunnels --
> Cascade, Flathead, Moffat -- are somewhat at the
> limits of what can be ventilated reasonably
> efficiently. And even there, the ventilation
> process is a substantial capacity inhibitor.
>
> In Europe, of course, the predominant form of
> railroad motive power is electric. The new base
> tunnels are all twin-bore, with directional
> running in the bores, which makes them somewhat
> self-ventilating, though there is usually some
> provision for supplemental ventilation.
Regarding twin bores (or drilling second bores parallel to present tunnels), I had a thought that a new second tunnel should have the opposite grade profile of the present tunnel. That would allow both directional running within the tunnels but also allow each one to act as a drift tunnel, wherein the consists could just coast downhill within the tunnel. That would eliminate the need for either fancy ventilation systems or electrification, e.g. it would fit perfectly for the diesel generation.
That's an idea that might work for the Stevens Pass line, although a new bore with an opposite grade profile would need to be at least twice as long as the present Cascade Tunnel with an east portal somewhere near Merrit or Nason Creek.
Another tunnel that comes to mind regarding a new parallel bore with an opposite grade profile would be Mullan Tunnel on the MRL in Montana.
But of course such an idea wouldn't work for Stampede, since it is such a weirdly shaped thing.
Just more random thoughts.
-------------------------------------------------------
>
> The problem with very long tunnels and diesel
> operations (in the U.S.) is, of course,
> ventilation. The longest U.S. rail tunnels --
> Cascade, Flathead, Moffat -- are somewhat at the
> limits of what can be ventilated reasonably
> efficiently. And even there, the ventilation
> process is a substantial capacity inhibitor.
>
> In Europe, of course, the predominant form of
> railroad motive power is electric. The new base
> tunnels are all twin-bore, with directional
> running in the bores, which makes them somewhat
> self-ventilating, though there is usually some
> provision for supplemental ventilation.
Regarding twin bores (or drilling second bores parallel to present tunnels), I had a thought that a new second tunnel should have the opposite grade profile of the present tunnel. That would allow both directional running within the tunnels but also allow each one to act as a drift tunnel, wherein the consists could just coast downhill within the tunnel. That would eliminate the need for either fancy ventilation systems or electrification, e.g. it would fit perfectly for the diesel generation.
That's an idea that might work for the Stevens Pass line, although a new bore with an opposite grade profile would need to be at least twice as long as the present Cascade Tunnel with an east portal somewhere near Merrit or Nason Creek.
Another tunnel that comes to mind regarding a new parallel bore with an opposite grade profile would be Mullan Tunnel on the MRL in Montana.
But of course such an idea wouldn't work for Stampede, since it is such a weirdly shaped thing.
Just more random thoughts.
