the above attemps to illustrate the blocks for crossover tracks between between 2 double track mainlines. (please ignore the gray crossover and packet tracks)
my question is are the blocks in different colors correct for the signals as indicated
i'll leave it at that to avoid stating what i believe is obvious.
signals not only depends on block occupancy, but switch settings, so STOP signals are indicated whereever a switch is not aligned for a train to proceed.
blocks will be reported as occupied even when a train is only occupying a portion of the block
an approach signal would simply be indicated whereever a switch is aligned for a diverging route
greg - Philadelphia & Reading / Reading
gregcthe above attempts to illustrate the blocks for crossover tracks between between 2 double track mainlines.
Are they double track, i.e. rule 251 current of traffic, or are they CTC, or is this a big interlocking?
Are you asking about the signal's physical locations? The answer depends on my first question.
Just looking at it, it doesn't seem to be "prototypical" but it seems probably adequate for a model. You generally don't get diverging approach signals in rule 251. In 251, the dispatcher doesn't generally line switches or signals, if the dispatcher is lining switches or signals, it's generally CTC or an interlocking, which is a different set of signal locations and aspects.
Dave H. Painted side goes up. My website : wnbranch.com
thanks
yes, double track mainlines (B&O and western maryland)
don't know the difference between 251, ctc and big interlocking
actually asking what the blocks should be for block detection to support ?? signaling
dehusmanif the dispatcher is lining switches or signals, it's generally CTC or an interlocking, which is a different set of signal locations and aspects.
there's a tower
what would the differences be? (what would i need to understand)
Are those powered switches intended to be part of an interlocking, or all hand thrown?
If powered, you left out 9 or 10 more interlocking signals which should be there...
Rule 251 current of traffic, double track is ABS in one direction on each track. No signals on the other track. All the switches are hand operated (not lined by a dispatcher or control operator) and the signals are driven by switch postion and track occupancy. At train that wants to go on diverging route needs to stop, establish protection on the opposing track, manually line the switches and then proceed. After transiting the route, they have to stop, linea nd lock the switches for normal behind them.
With CTC or an interlocking, a dispatcher or control operator lines the route and clears the route prior to the trains arrival, the train transit's the route on signal indication.
Also repmenber that since it is two railroads, its two routes, totally separate, two dispatchers, totally separate, if it's CTC or an interlocking, it's two CTC systems or two interlockings, totally separate.
The top CTC or interlocking would see the top two mains, and maybe the first switch in the two yellow tracks in the connection. The bottom CTC or interlocking would see the bottom two mains and the siding and maybe the bottom switch in the two yellow tracks in the connection. The bottom dispatcher can't see anything on the two mains on the top, the top dispatcher can't see anything on the bottom two mains or siding on the bottom.
If it's rule 251 the dispatcher can't see anything, there is no display screen or control panel.
dehusmanAlso repmenber that since it is two railroads, its two routes, totally separate, two dispatchers, totally separate, if it's CTC or an interlocking, it's two CTC systems or two interlockings, totally separate.
Not necesarily. There's plenty of places where 2 railroads can cross over at an interlocking - but only one RR controls the entire thing. I use one regularly. Even if we go from our track to our track, the other RR controls the signals/switches.
Since Greg says there's a tower - I'm assuming they control the interlocking. That case, there'd prob be at least pot/dwarf signals for running against current of traffic in 251.
But back to the original post - what's with the double yellow section? Seems like that would be a single track if the whole thing is one interlocking.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
my question is really only about understanding where to put gaps for block detection, although understanding signalling is also interesting
i'm working on lighting up signals on a 17 year old club layout. after reblocking some of the track, we're left with a dead section of track that i need to rewire and trying to figure out the best way to do.
the club is using PSX circuit breakers which also have block detectors to separately power each of the colored blocks in the original diagram. i believe i need to add an additional circuit breaker for the yellow section of track. it is currently wired together with the green block
if there's nothing seriously wrong with the blocks i've illustrated, i'm curious about is how a train going thru the above route will partially occupy two other blocks (blue, pink) and if this is common?
Prototype answer is that it doesn't "share" blocks, those little pieces of pink and blue are their own blocks.
now i'm getting curious.
in the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC.
the following diagram is from Classic Railway Signal Tower : New Haven Railroad S. S. 44/Berk. it illustrates the devices (including derails) controlled by the tower and the sequence they need to be changed for one case
wouldn't something similar be done to handle that crossover in the case i describe? signals would be controlled by the tower, not by block occupancy.
and is this what is meant by rule 251?
gregcin the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC.
Nope. CTC and interlockings have essentially the same requirements and rules. Interlockings only control to the home signals of the interlocking and CTC typically (but not always) extends out to the surrounding mains.
gregcwouldn't something similar be done to handle that crossover in the case i describe? signals would be controlled by the tower, not by block occupancy.
What you have shhown is an INTERLOCKING. What your model railroad has built is an INTERLOCKING. What signals you drew in your diagram were for Rule 251. An interlocking has over twice as many signals as what you have drawn.
gregcand is this what is meant by rule 251?
NO. Imagine two main tracks extending 200 miles. On the north track there are ABS signals for movement west. There are NO signals for eastward movement. On the south track there are ABS signals for eastward movement. There are NO signals for westward movement on that track.
A train gets on the north track and goes west. A train gets on the south track and goes east. Repeat as many times as you like. There are no towers, there are no train orders, there is no control panel. The dispatcher can't "see" where the trains are. The operators along the line OS the trains to the dispatcher.
That is rule 251 and it was the most common way to operate double track in the US and Canada.
Part of the issue is you are looking at it as a model railroader so you see a "crossover".
A real railroad would not. Especially if it were two different railroads. It would be a junction or an interchange, but not a crossover.
I received a question about what's the difference between CTC, "tower" and interlocking operation.
First there is no real "tower" operation. In most cases a "tower" is associated with an interlocking, so in most cases a "tower" = interlocking.
A tower facilitates seeing over one track to what's going on on another track. There is no rule that a interlocking has to have a tower. Generally towers were built back in the day when they were manually operated by a mechanical or pnuematic system and trains had to be visually identified. Once they went to better detection, control and communication systems, they didn't need towers and didn't need to be manned locally. In the 1960's and 1970's radio became common and better detection was installed and manned towers were changed to remotely operated from hundreds or thousands of miles away.
The difference between CTC and interlockings is more in the scope of control. CTC tends to cover miles of railroad, while interlockings are more of a "point solution" covering one location. The operating rules for CTC and interlockings are very similar. Many interlocking towers were made part of the CTC system.
ok, it's not a "crossover"
dehusman gregc in the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC. Nope. CTC and interlockings have essentially the same requirements and rules. Interlockings only control to the home signals of the interlocking and CTC typically (but not always) extends out to the surrounding mains.
gregc in the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC.
nope?
this comment suggests that tower had/needed electrical block detection just as CTC does.
This tower existed long before CTC existed. It was replaced in the 1990s and of course the tracks needed electrical block detection before being placed under CTC.
my understanding of towers is they typically aligned the track and -- set signals as a last step -- for scheduled trains to proceed thru the interlock.
however, in this case, the tower also needed to support trains stopping, pusher engines being uncoupled and returning or being located on pocket track.
track panel from the B&O Sandpatch Tower
would like that phone call
The engines in your pictures are modern engines. Are you modeling 1890 or 1990? Era makes a difference. If it's 1890 then there wouldn't be any detection. If you are modeling 1990 then the detection would be virtually the same.
Part of the problem is that the people reading only have the information provided. It wasn't until several posts later that we learned that it was two different railroads (makes a HUGE difference in how the trackage is configured). It wasn't until several posts later that the yellow connecting tracks were described as "interchange" tracks (that makes a HUGE difference in how those tracks are configured).
Every time additional information is added, it can change what was originally suggested.
Since it's two railroads, it would be two different routes, two different dispatchers, two different interlockings, one for the B&O, one for the WM. If you are modeling post Chessie, it might be one railroad but it would still be two different routes, two different dispatchers, two different interlockings.
If those yellow tracks are just interchange tracks where each railroad sets out a cut of cars for the other then they are not "main tracks" and probably wouldn't have any detection at all, they would be the same as the grey tracks. The operator might control the switch in the main track into the yellow area but the inside yellow switches might be hand operated and not controlled by the operator.
You have signals for right hand running. If its an interlocking then there has to be signals for every entrance into the limits. That means you need a whole set of signals as if you were left hand running, that's why several people have told you you only have half the signals.
gregcdehusmangregcin the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC. Nope. CTC and interlockings have essentially the same requirements and rules. Interlockings only control to the home signals of the interlocking and CTC typically (but not always) extends out to the surrounding mains.nope? this comment suggests that tower had/needed electrical block detection just as CTC does. This tower existed long before CTC existed.
dehusmangregcin the days of towers, i assume the track under control of and visible to the tower may not be electrically blocked as it might need to be for CTC. Nope. CTC and interlockings have essentially the same requirements and rules. Interlockings only control to the home signals of the interlocking and CTC typically (but not always) extends out to the surrounding mains.
this comment suggests that tower had/needed electrical block detection just as CTC does. This tower existed long before CTC existed.
dehusmanAre you modeling 1890 or 1990? Era makes a difference.
sorry if i wasn't clearer, but i don't understand why current operating era is relevant to clarify if electrically detected blocks were needed for a tower that operated before CTC
... phone call?
it's not a question about signals