When it comes to my railfan knowledge, signaling and train dispatiching is my “Achilles heel.” As such, I have several rather basic questions:
1.) What are ABS, CTC, and DTC, how do they differ from standard signal blocks, and how do they work?
2.) Why do railroads use Track Warrants, instead of just standard timetables and train orders like they used to, telling trains where to go and when?
3.) Why did railroads switch in the first place?
4.) How do railroads keep track of their massive fleets of cars and locomotives?
These may seem like very basic questions, but I am truly in the dark in this area of railroading. Any help you could give me would be most appreciated.
ABS is Automatic Block System. CTC is Centralized Traffic Control. The dispatcher can control the positions of some switches and can clear signals over those switches. The signals between the controlled points are basically ABS. DTC is Direct Traffic Control is not a signal system. It is a method of granting track authority verbally. It is a modern version of manual block control (more or less). DTC can be used on a territory with ABS.
Track warrants, DTC and Form D’s allow main track authority to be granted verbally and are much easier to issue and understand.
see Q2.
Computers. Its not like they can wander off. AEI helps.
Dave - I am really impressed however… what is a Neophyte and what do those signals look like
Also, Dave… you should add your E-mail Etc to your profile, because if people have REALLY stupid questions they can e-mail you seeing as you have a very good bank of knowledge
Authority is required to occupy the main track. Your questions all revolve around authority.
The timetable is one way to grant authority. Train orders are another.
In CTC any absolute signal indication other than stop grants authority to the end of the system or the next absolute signal.
DTC and track warrants are used in non CTC territory to grant authority. While they seem quite a bit different at first they really are not in a logical sense. The difference is in how you designate track segments. In DTC it is by blocks. With warrants it is from station to station or between stations. I think DTC is a bit more intuitive and easier to use on a busy territory but to my knowledge only SP used it. Track warrants may be given by radio and copied by the crew, but there is more “stuff” on them than was used in DTC.
ABS signals do not convey authority. ABS signals are usually identified by a number plate. Controlled signals (in CTC do convey authority) to not have a number plate. In the past some railroads marked these as “A” (absolute) signals. You absolutely can not pass them at stop, where most block signals you can stop and then go on at restricted speed.
This is not a complete discussion of authority. The authority rules are very basic to safe operation and they are “just so” rules, meaning that the proceedures involved with them must be done “just so.”
Daniel: Mac and Dave have done an outstanding job of providing concise yet accurate answers for you, not at all easy given the great complexity of the questions asked you asked. I would highly recommend you search in Google for GCOR (General Code of Operating Rules). You can find it as a pdf, but expect to print out a few hundred pages. It has a list of definitions at the end which will answer some of your questions and explain stuff that we can’t get into here, unless we want to retype the whole thing!
I dispatched extensively in DTC territory at Kansas City Southern, and learned TWC at BNSF, so I think I can add a few things to Dave and Mac. SP was a major user of DTC, but as far as I know UP has by now converted all SP DTC territory to TWC. KCS continues to use DTC. Of interest, KCS DTC is actually a manual block authority, which allows trains faster maximum speeds. Normally, “dark” (unsignalled) territory is limited to 49 mph for freight, but if you have manual blocks you can exceed that.
Originally, all railroads dispatched by timetable and train order. The timetable established authority for every scheduled train, designating meeting points and the exact time a train left a station – the train could run behind its timetable time, but NEVER early. The timetable stated a hierarchy of precedence: eastward trains (usually) had rights over westward, first class over second, second over third. If all goes perfectly, every train can run entirely by the timetable and a watch, needing only a clearance card from the dispatcher to leave its originating station. You can even run an “extra” train – a train which has no timetable authority whatsoever, and not even need a train order to grant you authority, assuming the railroad is not too busy. All the engineer and conductor have to do is run against the authority of the scheduled trains, that is, inbetween their times, ducking out of the way into a siding when a scheduled train becomes due.
Kevin,
Neophyte signal are the signals given by brand new conductors and switchmen.
Usually ignored by old head engineers, thank god!
Stay Frosty,
Ed[swg]
I listen regularly to radio traffic on the Montreal Secondary - Syracuse to Massena, NY. Mark’s comments on tracking locos are reinforced every time I hear a NORAC “Form D” given out. The only question the NE dispatcher ever has for the crew is which unit is in the lead, most often on the locals, as they can get turned around.
The “Form D’s” I hear usually refer to specific landmarks (those little signs along the side of the track - KALB, RIVER, RICE), although I do hear an occasion reference to a milepost, usually for the locals, and the south end of a siding that is the location of many meets. (Random thought - they should name it something. “South end siding Philadelpia” is a bit wordy compared to the examples above.)
The track usually given a train by the DS ranges from one section (between two adjacent landmarks), to the entire line (from current location to terminus of that train). It all depends on traffic at the time. If there is a lot of traffic, the DS will ask the crew to “Give me BRAD (or whatever) when you can” so he can give that block to a following train.
While I’ve seen references to “Form B” in the forums, I’m pretty sure that I hear the track foreman getting Form D’s if they take a section of track out of service. If the track is capable of handling a train during the maintenance window, the train crew must clear it with the foreman who has the Form D.
Scott: I think I am correct in not inferring that you said I said DTC was foolproof. I only said that it’s perceived to have certain safety advantages over TWC.
“After arrival of” provisions have been stripped out of TWC on some railroads as well. I can think of at least 10 recent collisions, some fatal, mostly between trains and maintenance-of-way equipment, due to failure to wait for the train specified in the “After arrival of” line. There’s nothing inherently unsafe with that aspect of the rules so long as people obey the rules. If they don’t … God help them.
OK, so people seem to get the After arrival of feature wrong. But stripping it out isn’t a perfect solution, either. Without that line, you force two authorities instead of one onto the dispatcher and train crew: one to get the train to a meeting point, and a second at some later time to get the train out of the meeting point. That slows everything down, and doubles the opportunity for a missed repeat.
I am baffled how “dispatcher error” could have any inclusion in the cause of the accident you discuss, based on the information you provide. I read the NTSB report you linked (which is only a summary, unfortunately). All dispatcher transmissions are taped. He or she either issued a valid DTC authority, or they issued an invalid DTC authority. The crew said one thing, or they said another thing. Period. There’s no room for argument here in the example you cite. DTC authorities are created on a computer, which has built in logic-checks that prevent lapping authorities. You cannot override the machine and create a lap. However, you CAN read one thing on the screen, and tell the crew another thing – and I know of instances of it, both accidental and believe it or not, intentional. But that would show up on the tapes, because the DTC computer records every key stroke and display. If it showed one thing, and you said another thing, you are pulled from service on the spot, and in this case, probably fired.
Dear everyone,
I would like to express my greatest gratitude for all you have taught me. I have learned more about how railroads operate in the past half hour reading your responses than I have learned in the past five years.
However, what you have taught me has raised two new questions in my mind. Please forgive me if I missed something in what you have written that already answered these. Firstly, what if anything is the difference between ABS and manual blocks? Secondly, if TWC systems are designed to prevent lapping, why does TWC territory have signals? If I have misunderstood what you have been telling me, then I am quite sorry.
A good question. I’m not sure I can explain it satisfactorily (can someone else?). At this point, you really need a rule book to go into this kind of detail.
I have to partially start over to try to answer it. An ABS – automatic block signal system – does not convey authority to occupy the main track. It merely advises of track conditions ahead. The following things will turn an ABS signal red: a broken rail (most of the time), an open switch, and a train in the block. This gives you a higher degree of safety than no signal protection, and the FRA (and before that the ICC) allow you a higher maximum track speed as a result. Since an ABS system conveys no authority, you must have something that gives it: a train order, track warrant, DTC authority, yard limits, timetable, signal indication from an absolute controlled signal – one of these. These signals are called automatic because they respond to track conditions entirely on their own. They are not controlled by anyone.
A manual block is merely a paper system that divides the railroad into blocks. It’s called manual because a human assigns the block. The block limits are established and fixed, but they only exist on paper (and a signpost at their entrance). Unlike an ABS, they do not automatically clear themselves or assign themselves. And unlike an ABS, they DO convey authority but DO NOT tell you anything about track conditions.
In manual block, by rule you cannot have two trains in the same block at the same time unless both are at restricted speed (prepared to stop in half the limit of vision short of train, engine, red signal, men and equipment, and open switch, keeping a sharp eye out for a broken rail and not to exceed 20 mph). In ABS-TWC, there are no blocks per se, only “signaling blocks” which have no authority attached to them at all. TWC rules allow you can have two trains in the same signalling block at the same time without both being at restricted speed, so long as train
maybe i can help clear the mud to just dark water .
In abs system it is a signaling system that tells track condition only. nothing more nothing less. A block is the section of track between to signals governing movement in the same direction. and a absolute block is a section of track that can only be occupied by 1 train or engine at a time.
TWC - track warrent controll can be in abs or dark territory . you can have trains overlapping in twc in dark territory following each other but you must have the rule 99 flag protection not required for following trains . ( it gets worse but hang in there) if i am running in dark territory with a train following we stay in radio contact knowing where each person is and knowing train size helps. if i am at milepost 5 and i am 1 mile long my rear just cleared mile post 6. the train at mile post 10 is 4 miles behind and safe. if i go into emergency i must announce this over the radio and the following train will stop. this keeps me from having the conductor get off the train run 2 1/2 miles back to flag stop the train behind . rule 99 says we dont haft to flag the train.
the other way it is done in same circumstance is the dispatcher will give a warrent to the following train only to my last “os” I might get a warrent from mile post 20 to mile post 0 a procede with a rule 99 checked. in 10 min the dispatcher might ask for my location . this is a must not lie or strecth the truth ever. if i am at mile post 17 dont tell him 12. cause they will “os” ( last location) of rear of train 3miles ( mile post going down 20-19-18 etc.) back. so he says i am clear of the 15mp.( remeber i said i was at the 12 when i am realy at the 17 we stopped for icecream) and at mp 16 we go into emergency. train “B” has a warrent to the place i said i was clear of 15 and hits the rear of my train at the 17mp ( remeber this is dark territory no signals.) this is the reason for good communications and absolute blocks.
Wabash, Everyhting you said was perfectly Clear, Except that paragraph above. I might be looking at htis like a dumb Idiot, But up here, apssing Absolute signals is a no no, unless I get a 567 from the disspatcher.
Thats never happened, and doesnt happen often, But I don’t see how a 567 would affect Absolute signals and the movement of trains and the ability to pass them, however the 567 is what we need to be able to pass an absolute signal… Someone know how these two corrilate?
[quote]
QUOTE:
567 JOINT WORK AUTHORITY TRAINS AND ENGINES
(a) More than one train and/or engine may be given joint work authority which permits movement in either direction within the specified limits. Each crew requesting such authority will communicate with the RTC. Such communication must include the occupation and name of the crew member, the train or engine designation, the location, the required limits and the track or tracks to be used. Each such train or engine must be instructed:
‘Protecting against each other.’ When so instructed, and protection other than that prescribed by Rule 99 is to be provided, the conductor and locomotive engineer of each train or engine must first have a thorough understanding in writing with resp
Under the GCOR trains stopped at a Stop signal (absolute stop signal, no number plate) are to attempt to contact the dispatcher. If they cannot, and have authority past the signal, they pull 100 feet past the signal, wait 10 minutes then proceed at restricted speed.
I do not find the provision you are quoting in my GCOR.
Rule 9.12.1 and 9.12.2 provide for dispatcher or control operator to talk a train by Stop indications in CTC and Manual Interlockings respectively. That is only way by an absolute stop signal that I know of.
9.12.4 A.
On a main track, after stopping, a train authorized beyond signal must comply with one of the following procedures:
If authority beyond the signal is joint with other trains or employees, proceed at restricted speed.
or
Proceed at restricted speed when crew member has contacted the train dispatcher and recieved permission to pass the Stop indication. However if the train dispatcher cannot be contacted, move 100 feet pest the signal, wait 5 minutes, then proceed at restricted speed.
What i was saying is that in track warrent territory with abs signals this is the way it is done. EXcept ( i didnt put this in as not to confuse anyone) at interlockings . the dispatcher wont have controll of the interlockings in abs territory.
In other words as long as i have a warrent to proceed past the absolute signal and i cant get radio contact with the dispatcher provisions allow me to go 100ft past signal wait 10 min then proceed at restricted speed. dont mix ctc with abs they are 2 differant critters.
In the senerio i gave the absolute would be at the end of another siding .
mac and kevin in ctc territory the absolute are differant than in abs. to understand track warrents( this is what i was trying to clear up) just think of them as a ticket to go from point “a” to point “D” . On the ns are track warrents are only 1 small page with 12 boxes. the BNSF has at least 25 i know of… less is better. the way the ns likes it is give all the info in the smallest amount of words. but back to the lesson in twc once granted and the ik time is recieved the only way this warrent is no good is if i give it up. it cant be changed or altered. so if the dispatcher made me mad i can run slow and hold up the railroad and there is nothing he can do about it. in ctc he can take a signal back ( if you are not close and no chance of running a stop) and hold you for a opposing train. with out telling you. this is why in abs and track warrent territory you can pass a stop with out being fired as long as you have athority to go further.