Fostoria signal question

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Fostoria signal question

Unread postby DaveO » Fri Oct 25, 2019 11:38 am

Watching Railstream this morning on their youtube freeview.

I watched as a westbound CSX train crossed the NS.
It had a green over red (clear) which dropped to red over red (stop)
After it had gone several hundred feet past the NS diamonds, the signal went red over lunar (restricting). This struck me as weird. After some thought, I do understand the use as the route across the diamond was still lined for CSX usage.
As the train proceeded west, the signal went yellow over red (approach) and then finally to green over red (clear) just in time for the next train.

So that got me wondering about this...
When they closed F tower, did they do any modification to the signal layout? Did they remove some and simplifying the layout? Maybe they added some or moved some?
Just curious.
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Re: Fostoria signal question

Unread postby trainjunkie47 » Fri Oct 25, 2019 9:34 pm

I could be wrong, but I don't think anything changed. I think it was just a case of the first train hitting the next two blocks before the second train arrived? The next block going westbound is a set of crossovers. Possibly the first train took the crossover, or the second train was lined to take the crossover after the first train cleared. Several possibilities.
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Re: Fostoria signal question

Unread postby Saturnalia » Fri Oct 25, 2019 10:54 pm

Probably seeing more restricting now if the dispatchers are using automated computer-line ups and fleeting more often than perhaps the tower operator used to. Perhaps in the past the tower operators didn't line up trains quite as fast as the remotes and their computer overlords do now.

Which begs the question, to what extent is CSX's dispatching automated these days? Are dispatchers still clearing every signal and making the line-ups themselves or babysitting the computer?
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Re: Fostoria signal question

Unread postby DaveO » Sat Oct 26, 2019 9:15 am

I think Saturnalia is on the right track saying that the F Tower Operators were more in control of the movements than a remote dispatcher will ever be able to.
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Re: Fostoria signal question

Unread postby Typhoon » Sat Oct 26, 2019 7:05 pm

DaveO wrote:I think Saturnalia is on the right track saying that the F Tower Operators were more in control of the movements than a remote dispatcher will ever be able to.



You can think that but you would be wrong, as he is.
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Re: Fostoria signal question

Unread postby Typhoon » Sat Oct 26, 2019 7:08 pm

Saturnalia wrote:Probably seeing more restricting now if the dispatchers are using automated computer-line ups and fleeting more often than perhaps the tower operator used to. Perhaps in the past the tower operators didn't line up trains quite as fast as the remotes and their computer overlords do now.

Which begs the question, to what extent is CSX's dispatching automated these days?


On the western half of the railroad? Zero.
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Re: Fostoria signal question

Unread postby LakeATCS » Sun Oct 27, 2019 5:06 am

Only changes were some stuff on the NS side.
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Re: Fostoria signal question

Unread postby JoJames » Sun Oct 27, 2019 8:37 pm

Dispatcher clicked the mouse twice for a through route at wood street. Pretty common move with a train following another.
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Re: Fostoria signal question

Unread postby Saturnalia » Sun Oct 27, 2019 8:56 pm

Typhoon wrote:
Saturnalia wrote:Which begs the question, to what extent is CSX's dispatching automated these days?

On the western half of the railroad? Zero.

Are they in the process of trying anything out?
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Re: Fostoria signal question

Unread postby AndyW » Wed Nov 20, 2019 9:54 am

Hope you don't mind me tagging onto this thread as my first post. I'm a Brit who's been watching the Fostoria railcams quite a bit over the last few weeks, partly because it's a busy location and partly because there are signals in view.

I'm fairly new to US signalling practise, and although I've done some background reading it's always interesting to see the reality on the ground. Like the original poster I've also seen red over lunar at the CSX/NS diamond for a westbound train which was close behind another one. I assume the route has already been set for the second train and the signalling system is clearing the signals in rear of the first train automatically as that train clears the blocks ahead.

With this in mind I'm curious about how far the first train must go before the signal in rear will clear to red over lunar? Obviously for yellow over red the first train must clear the whole block ahead, but how does it work for red over lunar?

I also have a second question, which might relate to the first one. Does US signalling have the concept of what in Britain we'd call an "overlap"? In other words does the whole of a train not just have to clear a signal before a second train is allowed to approach that signal, but the first train have to clear a specific distance *beyond* a signal before a second train is allowed to approach that signal?

Part of the reason I ask this is because the westbound signals at the CSX/NS diamond seem pretty close to the actual crossing itself, and thus there doesn't seem to be much distance (or overlap) between the signals themselves and what we'd call the "fouling point", i.e. the point at which a train slipping past a red signal could potentially cause a collision. I've not actually seen a train approach any of the westbound signals at red, so I'm wondering whether this is even allowed at Fostoria?

And are the numerous road crossings a factor in the signalling design here, i.e. would the system be designed to hold trains further back rather than have them stand near the junction and block the road(s) for some unpredictable amount of time?
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Re: Fostoria signal question

Unread postby Saturnalia » Wed Nov 20, 2019 10:03 am

In US practice, an absolute signal can show a restricting as soon as the previous train physically clears the signal. Basically as soon as the track circuit leading to the signal is unoccupied, another signal can be coded to show up at something other than stop. As you said, it’ll upgrade to approach or equivalent “stop at next signal” once the track between the signal and the next one is unoccupied, the system’s way of saying the next block is protected.

Signals are sometimes designed to allow for holdout but it’s usually just based on moving the signals to where they’re easily visible to the desired hold point. For instance trains know if they don’t have better than approach coming up to the last signal before Fostoria that they won’t be clear all the way over the diamond, so they’ll hold at that signal and wait for it to upgrade. This is generally the practice to keep clear of as much stuff as possible but obviously varies by location and even train crew preference, but sometimes is also codified into the timetable for that particular subdivision.
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Re: Fostoria signal question

Unread postby JoJames » Wed Nov 20, 2019 8:46 pm

AndyW wrote:Hope you don't mind me tagging onto this thread as my first post. I'm a Brit who's been watching the Fostoria railcams quite a bit over the last few weeks, partly because it's a busy location and partly because there are signals in view.

I'm fairly new to US signalling practise, and although I've done some background reading it's always interesting to see the reality on the ground. Like the original poster I've also seen red over lunar at the CSX/NS diamond for a westbound train which was close behind another one. I assume the route has already been set for the second train and the signalling system is clearing the signals in rear of the first train automatically as that train clears the blocks ahead.

With this in mind I'm curious about how far the first train must go before the signal in rear will clear to red over lunar? Obviously for yellow over red the first train must clear the whole block ahead, but how does it work for red over lunar?

I also have a second question, which might relate to the first one. Does US signalling have the concept of what in Britain we'd call an "overlap"? In other words does the whole of a train not just have to clear a signal before a second train is allowed to approach that signal, but the first train have to clear a specific distance *beyond* a signal before a second train is allowed to approach that signal?

Part of the reason I ask this is because the westbound signals at the CSX/NS diamond seem pretty close to the actual crossing itself, and thus there doesn't seem to be much distance (or overlap) between the signals themselves and what we'd call the "fouling point", i.e. the point at which a train slipping past a red signal could potentially cause a collision. I've not actually seen a train approach any of the westbound signals at red, so I'm wondering whether this is even allowed at Fostoria?

And are the numerous road crossings a factor in the signalling design here, i.e. would the system be designed to hold trains further back rather than have them stand near the junction and block the road(s) for some unpredictable amount of time?



Road crossings have nothing to do with how signal system is set up.
Train crew is responsible for knowing the territory and where they should park and not park.
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Re: Fostoria signal question

Unread postby AndyW » Sat Nov 23, 2019 8:53 am

Thanks for the replies.

A couple more questions if I may. Firstly, I've seen a couple of trains go west on the CSX line with yellow over flashing green and, as far as I could tell, with nothing preceding them for a while. Is it possible to make any deduction from this, such as the train is likely to be switching tracks at the crossovers a couple of miles west of Fostoria? Obviously I'm not sure the line speed over those crossovers, which I'd assume is a factor in the signal aspects for trains that use them.

And secondly, I'm guessing from what I've read that the line west of Fostoria is bi-directionally signalled once you're out of the town, and away from the junctions. Notwithstanding this, would trains normally run on the right-hand track unless there was some reason for them not to?
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Re: Fostoria signal question

Unread postby JoJames » Sun Nov 24, 2019 8:57 pm

AndyW wrote:Thanks for the replies.

A couple more questions if I may. Firstly, I've seen a couple of trains go west on the CSX line with yellow over flashing green and, as far as I could tell, with nothing preceding them for a while. Is it possible to make any deduction from this, such as the train is likely to be switching tracks at the crossovers a couple of miles west of Fostoria? Obviously I'm not sure the line speed over those crossovers, which I'd assume is a factor in the signal aspects for trains that use them.

And secondly, I'm guessing from what I've read that the line west of Fostoria is bi-directionally signalled once you're out of the town, and away from the junctions. Notwithstanding this, would trains normally run on the right-hand track unless there was some reason for them not to?



Approach limited is the signal indication your seeing. This would mean limited clear at Godsend crossovers if nothing is preceding. Limited clear is red over flashing green and would only be seen wear crossover moves can be made at 45 mph.
All the former B&O is bi directional running and this was done for the ConRail split.
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