Signalling and ways of tracks

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Signalling and ways of tracks

Postby Fearguy1234 » Sat Aug 22, 2015 10:18 pm

Is it possible, to have a railroad completely outfitted with 2 railroad tracks, 1 on the right going one way and the other going the other way, like regular cars do on roads? And single tracks can only go one way? Would it be economical or make sense or are there better ways to do it? (Railroad signals only face 1 way the direction the train is coming in, not 2 ways.)
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Re: Signalling and ways of tracks

Postby DutchRailnut » Sun Aug 23, 2015 3:43 pm

Why would you reduce the capacity by nearly 50% compared to bi directional signalling and why would you tie up your railroad when maintenance were to be done on one track ?
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Re: Signalling and ways of tracks

Postby Greg Moore » Mon Aug 24, 2015 12:41 pm

An experienced railroader can weigh in and correct my terminology but:

Essentially what you're describing is the way that many railroads used to operate, trains, except in rare situations always ran in the same direction on the same tracks.
What this meant though was that you were limited in how many trains you could run in either direction (imagine a situation say where commuter trains are running into a city. Outbound trains in the morning may be infrequent, but inbound may be frequent. However, since you have multiple stops, express trains would get held behind the stopped trains. By permitting both tracks to be used in either direction, you can easily have express tracks on the left hand tracks and locals on the right hand. Then reverse things in the evening.)

Note that even with this, it was always possible to operate "against" the direction with specific train orders.

As for one-way tracks. Sometimes you see this with freight lines, especially where two railroads have merged. What formally may have been a bidirectional single track may be used in one direction only due to its grade (i.e. heavy loads taking the longer, but less steep grade up to the top, and other loads coming down on the steeper track.)
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Re: Signalling and ways of tracks

Postby Backshophoss » Mon Aug 24, 2015 7:43 pm

BNSF has directional running between Pueblo Co and Amarillo Tx,using the former BN(C&S/FW&D) in 1 direction,
the former ATSF route in the other direction,this is done for unit coal trains from/to the Powder River Basin.
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Re: Signalling and ways of tracks

Postby BR&P » Tue Aug 25, 2015 11:27 pm

There are multiple reasons why it would not e desirable to have an "absolute" 1-direction only track (as opposed to one which is USUALLY operated directionally but retains the capability for bi-directional running). But one factor would be that not all trains run at the same speed, nor do all trains stop at the same places.

For example, train A may be experiencing power problems and is only ably to limp along at 30 mph. Or maybe train A has a car in the consist which is limited to a certain speed. Train B may be a hotshot, lots of power, important cargo - do you want THAT train to have to poke along behind train A, or go around and be on its way fast?

Likewise a train may have some cars to be set out at an industry or an intermediate yard. Absolute 1-way tracks would require all trains behind it to sit and wait while the first one does its work.

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Re: Signalling and ways of tracks

Postby BostonUrbEx » Sun Sep 06, 2015 12:13 am

What you're describing is known on NORAC railroads as Rule 251 territory. Running against the signaling is possible via track warrant (in NORAC the warrant is called a Form D). However, it is still a capacity reducer and really costs time if things go wrong.

I know 251 territory exists on the MBTA in Massachusetts in some locations, but it is dwindling for good reasons. One spot is the Haverhill Line between the Fells interlocking (Malden/Melrose line) and Reading.
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Re: Signalling and ways of tracks

Postby ctclark1 » Sat Nov 07, 2015 8:34 pm

I know at least as recently as 2008, NS operated nearly 40 miles of the Southern Tier line from BD (Binghamton) to WAVERLY as 251, as well as a short section from CP-DRAW through Tift Yard to BLASDELL (just north of the old Buffalo Line flyover). The latter section is relatively slow running however as EB trains tend to stack waiting to cross CP-DRAW and WB trains are just starting out through Tift Yard heading down the Lake Erie District line. The former section noted was run as 251 by Conrail all the way to the Portage Bridge before being single tracked.
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