I have a question about the authority of trains leaving a spur entering the main track under an ABS/APB signal system. I’m setting up a signal system on my layout, and I’m curious about this. With ABS/APB with Track Warrants, what are the rules for, let’s say a single locomotive with 2 cars, pulling out of a 1/2 mile spur onto the main track. Do they open the switch (align it for the spur) and just proceed or do they open the switch and wait 5 minutes or so before proceeding onto the main? With many spur tracks, there are no signals to govern movement from the spur onto the main. Do they rely only on dispatcher approval? The only indication is the switch stand with the markers on top indicating switch position. I realize that once you open the switch, it will drop the signals at both ends of that block to red, but what prevents a train in the spur from pulling onto the main in front of a train on the main already moving through at full speed within that block? Sidings normally have leave siding signals, but what about spurs without any signals?
Going back to an older set of operating rules in Canada, first of all the train would have had to already have some form of operating authority, usually in their sheaf of “train orders”. By the switch you would find a “block occupancy indicator” (BOI) which would show red in some form if there was another train already on the main. I’m not sure how far back the circuits would extend, probably two signals. Assuming the BOI was clear, they would throw the switch, and then still wait the five minutes to protect against a train passing the first signal at that very instant.
Today with direct radio communication with the dispatcher, if he/she gives them unconditional authority to occupy that piece of track they can just turn the switch and go.
Yeah, the only thing is that the NS line I live by doesn’t have any form of block occupancy indicator for spur tracks to move onto the main (at least none that I know of). It has an APB (ABS) signal system, but the ground throws only indicate whether they’re open or closed by the red and white target on top. Normally, if a train were to arrive to set out some cars, they would arrive, do their work, and then they would leave all on one authority. However, what I’m curious of is when they arrive and set a locomotive and a couple of cars off, go home, leave it there while several other trains pass (and their authority ends), and then the next day they decide to move the train to another location. The only thing I could be missing is if there might be an occupancy indicator located somewhere inside the signal bungalow. I’ve never seen them move a train onto the main after it’s been there for a while to know whether they just throw the switch or go by some indicator on the signal box. This block occupancy indicator that you mentioned, exactly where is it located most of the time?
You were right , you line the switch and wait for a conflicting movement. Usually your authority was the timetable, no other authority was needed unless you were an extra train in timetable days . Without a timetable your authority is a track warrant to either work or proceed on main track.
Throwing a main track switch in ABS with the block occupied is not usually possible , most have electric locks ,spur or siding, its still a main track switch.
Nobody occupies a Main Track without the Dispatchers authority…conveyed either by verbal means or signal indication.
Not always true in ABS. The train dispatcher didn’t control the signals. In the old days your authority was the timetable schedule. The dispatcher was expecting your train and it was up to you to depart on time in order to keep your timetable rights.
I don’t know if the ones through here have electric locks, because all I’ve ever seen are padlocks that keep the switch from being opened. If they do have electric locks, do they physically prevent a conductor from throwing the switch lever or can he still throw it but it just won’t re-align it? I looked through a 2000 timetable to this NS line, and it mentions electric US&S switches, but it doesn’t specify that they’re all like that or if any are like that. If they do have electric locks, they must not have that big of an impact because there’s this one switch located close to the end of a block with signals located several feet behind it, and I’ve seen locomotives pull up, leave several cars on the main in the block with the switch, pull into the next block just a few feet to clear the switch, throw it open, pull in get some more cars of a spur, pull out, immediately throw the switch again, and back up to get the rest of the train on the main.
I located some pictures of switch stands from rrpicturearchives.net that will hopefully demonstrate what I’m talking about. They’re pictures of the infamous switch at Graniteville, SC that caused the big derailment about 5 years, but they’re the same ones as what NS uses through here. I wish I knew where some better pictures were located, but these are the best I can come up with (I remember seeing them a few months ago when I looked at pictures of the derailment). Here’s the link to them: http://www.rrpicturearchives.net/showPicture.aspx?id=1868856 and http://www.rrpicturearchives.net/showPicture.aspx?id=216426
I think you are confusing a couple of concepts, authority to occupy the main track, and the five minute rule.
Authority to occupy the main track in the past came from either the timetable, for regular trains or from train orders for extra trains. The dispatcher created the authority for extra trains with and by the train order “Extra 123 run from here to there”. Today it comes from track warrants in dark territory or ABS and the track warrant has a line that says “proceed from here to there”. That is the authority to occupy the main track.
If a train is switching a spur, the usual course is to leave some of the train on the main track. In ABS that keeps the signals red. If there is no train then leave the switch open to maintain occupancy. In these cases the five minute rule do
So basically the five minute rule is what they go by. That’s what I thought, but I didn’t know if there was some hidden feature of the system that would affect a move from the spur/siding to the main. So, if you were moving off a side track onto the main and you had no leave siding signal, after receiving a track warrant, you would basically open the switch and stay there for five minutes to see if a train on the main comes roaring through. Most of the time there wouldn’t be a train coming through, but in the rare case that one does, you would immediately close the switch for the main track. Is this a correct understanding of this?
The block signals themselves can be used to determine if the 5 minute wait is needed. If it can be determined that no movement from either direction is approaching, you don’t have to wait.
All rule books have a rule that deals with this situation. The one I’m most familiar with is the General Code and it’s rule 9.17, Entering a main track at a hand operated or spring switch. Finding a copy of this, or other rule books will spell out when the wait isn’t required.
Jeff
The block occupancy indicators became redundant and were usually removed once the operating method in ABS territory changed from train orders and timetable to a manual block system where the authority to occupy a specific piece of track was issued directly to the train by the dispatcher. It eliminated a maintenance chore. (The manual block system has several names depending on the rule book used.)
The ABS signals are retained primarily for broken rail and non-aligned switch protection, and of course make it easier to fleet trains in the same direction. Just as train crews on very rare occasions don’t notice red signals, they have also been known to forget the limits of their current authority and continue on, and the ABS signals can help there too.
The electric lock that another post referred to was found in CTC territory. It had to be released by the dispatcher from his control panel, and I think usually there had to be a track occupancy by a stopped train in very close proximity.
John
Yes with qualifications. “Side track” is imprecise language and an indication of imprecise thinking. If you mean siding, a track auxilary to the main track to meet or pass trains, you are making the signal portion of it more complicated and the authority issue less complicated than it is.
In the ABS I am most familiar with, the Northern Pacific in eastern Washington State, there was no leaving signal. At the end of each siding there were two signals both beyond the switch, one in each direction. This is in contrast with a typical CTC installation which has three signals, one outside the switch usually two headed, top head for the main and bottom for the siding. There are two signals in the leaving direction, one for the main and one for the siding. All of these signals are absolute signals and an indication more favorable than stop conveys authority to occupy the main track to the next absolute signal.
Today in ABS if the dispatcher wants to make a meet at Somewhere, one trains has a warrant to Proceed from There to Somewhere, and a box checked ahead of a preprinted line that says “Hold the main track.” That box gives him authority to proceed on the main track beyond the first siding switc
For the signals to be used as you suggest…they must be visible. In many more cases where ‘industrial spurs’ or branch lines connect to the Main tracks, signals are not visible. The rules require opening the switch and waiting the required amount of time. If you want to spend some time in street clothes, just open up and go when the weed weasels see it.
Note - Electric locked switches are required on switches connecting to the Main track at points where Trains can clear the Main and the Main track normal speed is greater than 20 MPH.
Yes, there are places where you can’t see block signals in each direction and that exception wouldn’t apply. That’s why I said if.
The requirement for electric locks on hand throw switches where trains/engines can clear the main track and speed is greater than 20mph is found in our CTC rules. The main tracks I am familiar with that only have ABS don’t have electric locks on hand throw switches.
Even in CTC territory, leaving signals can be substitutted for electric locks. Almost all our hand throw switches in CTC territory have leaving signals instead. Even a spurs that are only a few cars long.
Jeff
O.k., I’ve been reading all of these posts, and while they’re all very helpful, they’re also kind of confusing and I think it’s because all of the railroads do things a little differently. Basically, this is what I’ve concluded from all of the posts on here and the timetable that I’ve read through for the NS line that goes through here: With the ABS system through here, there can’t be any electric locks because I have never seen them used and have no idea where they would be located if they were on this line. I have heard about and seen electric locks used in interlocking towers that basically prevent the signalman from lining up the switch improperly. I don’t know if that’s what some are talking about or not, but the timetable I have does mention US&S electric locks. From what I understand from these posts, it seems that the evidence is largely in favor of the idea that these electric locks are only for CTC. The timetable I have does mention US&S electric locks, but it includes not only this line, but also the Rathole line, plus some others, which I believe are CTC. The instructions for them are listed in the systemwide section, and it doesn’t say that all of switches are like that. The way it’s worded implies that some are like that and some aren’t. Therefore, I am going to conclude that on most TWC with ABS signal routes, the 5 minute rule is in effect when you leave a spur and enter the main after your warrant to go to the spur is voided and a new one to leave the spur is issued. All of the sidings through here have leave siding signals, and in the rare case that a train on the main stops, you have to push a button to start the timer for 5 minutes before you’ll get a diverging clear/approach depending on the next block’s occupancy. I believe the main signals also go to red during this time to bring any trains moving on the main to a stop. This 5 minute rule seems to be almost universal. Now, there is a coal junction about 30 miles from my
Here’s the website that I’ve been referring to that has helped me understand signal systems: http://www.lundsten.dk/us_signaling/
I’m posting a picture of the switch stand that is in question. I think a picture is worth a thousand words and is much easier to understand that me trying to explain this. Here’s a link to a picture of the switch stand that I’m talking about: http://www.rrpicturearchives.net/showPicture.aspx?id=2244909 The closest signals are about 1 mile away in each direction. The turnout goes to a side track that goes about 1/4 of a mile before it diverges back into the main. It is not a passing siding (I suppose it could be used for one) but instead goes to a local lumber business that receives a car of lumber about once every two months. They also use it to store maintenance of way equipment on when they’re doing track work. Does anyone have an idea of what would happen if a train sat on this side track for a day or two and then received permission to enter the main and proceed to another location? I know there would be a track warrant, but what about the signal rules? Is it simply the 5 minute rule like we think, or is there likely an electric lock or some sort of mechanism inside the metal bungalow box in the picture? I hope that posting this picture will take away some of the confusion of what I’m talking about exactly.
That’s a signal interlock/switch , not an electric lock,.