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Bi-Directional Signaling

You are here: Home > Forum > Miscellaneous > The real thing (signalling) > Bi-Directional Signaling

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Bi-Directional Signaling 12/03/2015 at 13:20 #69971
Ron_J
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In the early hours of this morning an infrastructure monitoring train developed a fuel leak, which caused the Down and Up lines into and out of Glasgow Queen Street station to become contaminated with diesel. For the first 60 chains the Up and Down lines run through a single bore tunnel at a gradient of 1 in 45 gradient; both lines are fully bi-directionally signalled as far as Cadder (4 miles away).

The first Up train of the morning didn't make it up the hill because of extremely low railhead adhesion caused by the diesel contamination. The Down line was less badly affected so for the first couple of hours of the morning peak all Up traffic ran over the Down line and Down traffic ran over the Up line, crossing over to the correct line at Cowlairs South Jn.

See, we can do it in this country!

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The following user said thank you: Hawk777
Bi-Directional Signaling 12/03/2015 at 13:58 #69972
Muzer
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Is it just me, or is it worse to have poor adhesion when you're going down a hill due to the potential inability to stop? I suppose they probably had some special arrangement whereby the signaller had to give the driver a completely clear road or something? Or is the affected area so small it doesn't matter much?
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Bi-Directional Signaling 12/03/2015 at 17:13 #69978
Hawk777
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I guess one might invoke the quantum observer effect: the infrastructure monitoring train tried to observe the infrastructure and, in doing so, altered that which it was observing
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Bi-Directional Signaling 13/03/2015 at 02:12 #69998
TylerE
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" said:
Is it just me, or is it worse to have poor adhesion when you're going down a hill due to the potential inability to stop?
All axles braked vs only a couple of axles powered.

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The following user said thank you: Muzer
Bi-Directional Signaling 13/03/2015 at 02:34 #69999
Muzer
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Point.
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Bi-Directional Signaling 13/03/2015 at 11:01 #70001
Danny252
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Does that apply to most modern DMUs? I was under the impression that they tended to be all axles powered.
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Bi-Directional Signaling 13/03/2015 at 11:05 #70002
jc92
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" said:
Does that apply to most modern DMUs? I was under the impression that they tended to be all axles powered.
158's and 156's are definetely only powered on one bogie per vehicle, not sure about 170's.

"We don't stop camborne wednesdays"
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Bi-Directional Signaling 13/03/2015 at 11:10 #70003
Ron_J
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Scotrail 170s have four powered axles out of twelve and struggle with wheelspin under accelaration at the best of times.
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Bi-Directional Signaling 13/03/2015 at 17:38 #70006
GW43125
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495 posts
" said:
" said:
Is it just me, or is it worse to have poor adhesion when you're going down a hill due to the potential inability to stop?
All axles braked vs only a couple of axles powered.
Still. I'd have thought they'd not risk it. There was a SPAD at Broughty Ferry some years ago where the line was shut for emergency services, the leaves on the line made the adhesion so low that despite the driver braking in plenty of time, the train slid through the signal and station at 60-70mph and overran the signal by a mile.

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