tree68 BaltACD Maximum speed for a hi-rail on CSX is 40 MPH - I have seen photographs of what happens when higher speeds are attempted on curves - it isn't pretty. We won't discuss switches... I've never dumped a hirail on a switch, but I've seen it done.
BaltACD Maximum speed for a hi-rail on CSX is 40 MPH - I have seen photographs of what happens when higher speeds are attempted on curves - it isn't pretty.
We won't discuss switches...
I've never dumped a hirail on a switch, but I've seen it done.
Excess speed on a curve
Never too old to have a happy childhood!
BaltACDMaximum speed for a hi-rail on CSX is 40 MPH - I have seen photographs of what happens when higher speeds are attempted on curves - it isn't pretty.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
JovetTo add to what BaltACD stated: Hy-rail vehicles are generally expected to behave as any train would. They cannot exceed the track speed limit, are required to obey Stop signals, etc.
Hi-rail vehicles do not operate on any form of signal indication. They operate on their Track Car Authorities only. If they have a authority through a Control Point, their only obligation is to see that the route that is lined is the one that their authority authorizes. In the CSX CADS the dispatcher must line the switches for the route through a Control Point if the authority is issued through and beyond a Control Point before the authority is issued.
Maximum speed for a hi-rail on CSX is 40 MPH - I have seen photographs of what happens when higher speeds are attempted on curves - it isn't pretty.
jeffhergertSpeed also plays a part in how fast the signals seem to drop to red. The detection point is the same, but the faster the train the more of it gets past the signal before it changes.
Yep. The time is the same, and represets the time it takes for the signal logic (relay or otherwise) to register the occupation of the track, update surrounding signals, and possibly communicate it to the dispatcher display. There is also a small delay usually designed in to prevent momentary false detections from wreaking havoc. All of this will vary by installation and individual signal, but it will be a pretty consistent amount of time for the same signal, regardless of the train speed.
MidlandMikeMy understanding is that a hi-rail vehicle would not be detected by a signal circut. How would a hi-rail know if it was safe to pass a signal if it would not (approach) light?
To add to what BaltACD stated: Hy-rail vehicles are generally expected to behave as any train would. They cannot exceed the track speed limit, are required to obey Stop signals, etc.
JPS1You got it. Thanks for the explanation.
Good, I'm happy to help. If you have any other questions, feel free to ask. Someone can try to answer them. None of us knows everything, but 40 heads are usually better than one.
Jovet Just to be clear, you're talking about here?: https://goo.gl/maps/sraQYWnbXFmXydad9
You got it. Thanks for the explanation.
The turnout is the route that the MKT's Texas Special ran over from Granger, TX to Georgetown, TX while enroute to San Antonio.
Except for a stretch of track near Georgetown that is used periodically for car storage, I believe the line is not usable, although the track is still in place.
Hi-rail vehicles operate on a Track Car Authority, the authority can apply to one or many pieces of track equipment (track gang tramming to/from their work location).
The operator of the vehicle contacts the Train Dispatcher and identifies where he wants to operate from and to and on which track if it is in multiple track territory. The Train Dispatcher through the use of the CADS creates a specific authority for the specific movement - the CADS system, in enacting the authority blocks off the ability of the Train Dispatcher to line signals into the limits of the authority. In TWC territory the existance of a Track Car Authority prevents the issuance of at Track Warrant for a train into that territory. The Track Car Authority will have a Time Limit for the holder to report Clear of the authority by. Track Car Authorities can be issued in a specific direction or in both directions. IF another track car operator wants to occupy the territory that a Track Car Authority has been issued for - the 2nd operator must contact the 1st operator that hold the authority to ascertain the conditions the 2nd opertor must observe to occupy the 1st operators territory.
That time limit is for the protection of the Track Car Authority holder - accidents do happen with personnel operating under Track Car Authorities - medical illness can overtake the operator and various forms of accidental happenings can prevent the operator from reporting Clear. After the time limit expires and multiple attempts to reach the holder of the authority via all possible means of contact have failed - and Division Management of the dispatch center have been involved - a train may be given authority to enter the affected track segement at RESTRICTED SPEED looking for the holder of the Track Car Authority - this is undertaken with great trepidation.
My understanding is that a hi-rail vehicle would not be detected by a signal circut. How would a hi-rail know if it was safe to pass a signal if it would not (approach) light?
Yes, Balt, watching signals change is an interesting hobby, whether you can see ahead or watch semaphores on single track from the rear.
And, riding in domes, you could explain some of mysteries of railroading to other passengers who did note the signals.
Johnny
Speed also plays a part in how fast the signals seem to drop to red. The detection point is the same, but the faster the train the more of it gets past the signal before it changes.
To illustrate this, I deadheaded by train this morning, riding the second unit also pointing forward. At track speed the block signal was still green when it went past the cab after the lead engine passed it. After stopping for a crew change, the new crew had to go slow to the next signal to allow PTC to engage, or it engaged and required restricted speed up to the next signal. We went by that signal about 10 mph and I could see that signal drop to red after the lead engine passed it.
Jeff
Watching the signals at Deshler shows them changing when the consist gets a car or two beyond the actual signal.
Sunnylandgood info and thx for input. Every time I rode UP City of St. Louis, and was in the dome car at night, the signal bridge always went from green to red when the dome car passed under it, must have been always in same spot in consist. Last year, when I was riding Texas Eagle south from Chi, bad storm near Joliet, knocked out power to signals. Every one was red and train had to stop until dispatch cleared them into the next block. And conductor had to get and hand throw the switch when we let our northbound sister train pass. Very old school, but interesting to see. We were about 3 hours late getting to St. L but made it safely. It was a very bad storm, rain drove very hard against windows and someone on other side of train saw a lightning bolt hit a wind turbine and spark around in a circle before the turbine shut down.
Signal systems, at least in the days BEFORE PTC, used numerous electrical relays. In changing the status of signal displays involved a cascade of various relays tripping and doing 'their thing'. I have no idea how many relays may be involved in permitting the display of any particular signal indication - but it is more than one.
Signals systems that have been upgraded for operation with PTC likely have electronic circuits performing the functions that relays previously performed and will likely change indication quicker than the old relay based systems.
Saw a video on YouTube made by a Signal Maintainer on the UP that briefly explained his job and some of the testing he does. In the video he showed a signal bungalow at a Control Point before PTC and the walls of the bungalow were filled with relays; a subsequent scene with the same Control Point AFTER it was upgraded to PTC and virtually all you saw was the footprints of where the relays HAD BEEN.
I also used to ride the dome car on the B&O's Capitol Limited when I was a kid - visually, it looked like the signal that the train accepted as Clear would finally drop to red about 3 cars after the engines passed the signal. If you watch some of the steam locomotive videos on YouTube you can also watch semaphore blades move to a 'stop' indication several cars after the locomotive moves past the signal.
good info and thx for input. Every time I rode UP City of St. Louis, and was in the dome car at night, the signal bridge always went from green to red when the dome car passed under it, must have been always in same spot in consist. Last year, when I was riding Texas Eagle south from Chi, bad storm near Joliet, knocked out power to signals. Every one was red and train had to stop until dispatch cleared them into the next block. And conductor had to get and hand throw the switch when we let our northbound sister train pass. Very old school, but interesting to see. We were about 3 hours late getting to St. L but made it safely. It was a very bad storm, rain drove very hard against windows and someone on other side of train saw a lightning bolt hit a wind turbine and spark around in a circle before the turbine shut down.
JPS1The stretch of railroad that I referenced is the UP from the BNSF intersection just south of Temple to Taylor, Texas. ... The line has a siding at Granger, TX. There are two overhead signals for the southbound trains and one by the side of the track for northbound trains. Yesterday both of the overhead signals were flashing yellow. What would that be about?
As for knowing how the approach-lighting behaves here, I would start with the basic belief that the signals turn on when a train is 3 signal blocks away, approaching the location... and that they turn off as soon as said train has passed out of the opposite, adjacent signal block. I would then observe the location and try to prove that wrong, and figure it out from there.
OvermodActually, as I remember the OP's question, it was about how a specific installation of approach-lit signals on a particular railroad was supposed to behave.
Unfortrunately, he did not name the railroad or the specific location.
The only way to really know how any particular signal operates is to sit there and watch it. Or drive around, observing how the signals work as trains move along, perhaps with a buddy. UP's approach lighting is very variable; BNSF's is a bit more predictable from what I've seen, but I've not seen as much of it.
JPS1Yesterday both of the overhead signals were flashing yellow. What would that be about?
Interesting... I took a look on Google street view and the two signal heads do appear to be as they would if they were signalling the two tracks. Normally, I would expect one to be at stop, as the signal would be against it (barring a run-through type switch).
Flashing amber is advance approach - be prepared to stop at the second signal.
There's a third track at the cantilever, but that appears to be an uncontrolled siding.
Our UP gurus should have an answer. I'm curious, too.
I might add that CSX (and maybe others) have overlaid PTC on Track Warrant Control territory. PTC enforces the limits of the TWC authority that trains are issued for their movement.
JovetThe OP's question was about how approach-lit signals behave.
Being a signal guy, this is my kind of thread! I'd like to add my 2¢. A link to my website with all sorts of signal rules is in my profile, too.
When it comes to operating trains, the first thing that matters is the method of working. There are various synonyms for that, but it comes down to the rules that govern the movement of trains especially on a main line. Each mainline is built to operate accrording to a set of pre-agreed rules. This keeps traffic as efficient as possible and prevents nasty accidents.
The main part of a method of working is (in the US) the traffic control system (TCS). Track Warrant Control, Direct Traffic Control, Automatic Block Signaling, Absolute Permissive Block signaling, Centralized Traffic Control, and Positive Train Control are the most-common traffic control systems in the U.S. Sometimes more than one TCS applies. For example, it has not been rare to have TWC with automatic block signals (ABS) as an added layer of safety. Another example: PTC is now a common addition to CTC. There are several other extant websites which describe these... I recommend this one to start with.
Technically speaking, some of these signal terms refer to only specific TCSes. An intermediate signal is only encountered in CTC territory. Unless you're CSX, an ABS signal is only encountered in ABS or APB territory.
The OP's question was about how approch-lit signals behave. The answer is: it depends! Different railroads set up their signals differently, and it isn't even always very consistant on the same railroad. Some approach-lit signals are only displayed when a train is in the block immediately in front of them; others display when a train is several signal blocks away. Some turn off as soon as the block in front of them becomes unoccupied... others turn off later than that. Sometimes it depends on which direction the train is moving relative to the signal.
cefinkjrExcellent summary, BaltACD; sounds like you might have studied the Rule Book a little bit over the years.
51 years in the Operating Department in various positions will do that.
Excellent summary, BaltACD; sounds like you might have studied the Rule Book a little bit over the years.
ChuckAllen, TX
PjS1 Keep in mind that different railroads have different rules governing their various divisions. You may even find differences between connecting sub-divisions. Basically we will assume you are watching an Automatic Block System, ABS, which can also be a CTC system with a PTC overlay. Do you understand these acronyms? if not we need to start a really basic course. Kalmbach and other publishers offer books on this topic and there have been many articles published on signal systems. ABS - Atomatic Block System is a system of insulated (isolated electrically) blocks that can vary in length depending on the maximum authorized track speed for that block or combination of blocks. Another factor is the average train tonnage in ratio with the braking power of each train. The conductor must figure out what the Train tonnage is per operative brake (TOB) to determine what speed they can run. So these factors combined with the local rules can have an effect on how long it takes for the red signal to go out. So there is not a consistent answer. Let us now figure each block is 2 miles long and the system is ABS with automatic approach lit signals. If the train is running at 60 MPH for the two miles it would take two minutes - BUT add the length of the train because the rear end of the train must clear the next set of insulated rail joiners. So if the train is a mile long it would take 3 minutes to clear the block. That means the signal light may go out if there is not another train following within the following block that would lite up the signal by shunting the circuit with the steel wheels and axles. Older ABS the lite would stay lit but change from red to yellow to green as the train rear end clears each block. So the red goes out regardless, it just changes to the next less restrictive indication. It was much easier watching trains before the signals were approach lit.
Also, watch for control points (CP) where signals are remote controlled by a dispatcher or operator like a draw bridge, crossovers, Junction or crossing with another RR. At a CP the signal indications are governed by the interlocking with the various switches, relays, and controls to provide a failsafe system. These signals can also be tied into ABS with relays and they can be approach lit too. Steve Rippeteau
Part 1 of a multiple part explanation of Canadian signals
https://www.youtube.com/watch?v=tJpR93kp44I&t=730s
Deggesty And, also from observation, in Canada, you can expect all signals to be numbered and, as I recall, absolute signals have two or more heads whereas intermediate signals have one head each (one of our good friends up north described the distinction in response to a question I asked several years ago).
And, also from observation, in Canada, you can expect all signals to be numbered and, as I recall, absolute signals have two or more heads whereas intermediate signals have one head each (one of our good friends up north described the distinction in response to a question I asked several years ago).
10000 feet and no dynamics? Today is going to be a good day ...
jeffhergertSpeaking of dispatchers and control operators, here's your chance to be one. This simulation was on one of my e-mail group lists. I've tried it once so far. One difference from the real world is that if you have two trains going the same direction and leave signals 'fleeted' but then hold the first train at the end of a siding, the following train will run into the stopped train ahead. There's no block signal protection against following trains. http://randallhook.com/railroad-dispatcher/play/ Jeff
This simulation was on one of my e-mail group lists. I've tried it once so far. One difference from the real world is that if you have two trains going the same direction and leave signals 'fleeted' but then hold the first train at the end of a siding, the following train will run into the stopped train ahead. There's no block signal protection against following trains.
http://randallhook.com/railroad-dispatcher/play/
That format of CTC machine has been replaced on the Class 1's with the various vendors CADS installations.
BaltACD,
Thanks for the great videos on signals. It appears that my question re: signals kicked off a great discussion; I am going to work on a couple more questions. Just as soon as I get back from watching #21 blast through Granger, TX.
Rio Grande Valley, CFI,CFII
Speaking of dispatchers and control operators, here's your chance to be one.
timz On SP single track in years past, with automatic signals but no CTC-- When an eastward train passed the east end of a siding, all the westward signals from there to the next siding would light up red, and all? the westward signals from the next siding to the siding east of it would light up yellow.
On SP single track in years past, with automatic signals but no CTC--
When an eastward train passed the east end of a siding, all the westward signals from there to the next siding would light up red, and all? the westward signals from the next siding to the siding east of it would light up yellow.
Absolute-Permissive Block style circuitry. It's also used with CTC, except I believe when the dispatcher lines up the route all opposing intermediate signals 'tumble' down to red. In either ABS/APB or CTC I don't think all signals beyond the next siding/control point go yellow. Only those in the normal occurance that protect where the first red would be encountered. If you understand what I'm trying to say.
APB also has the signal governing at the leaving end of a siding (called the head block) as an uncontrolled absolute*. If you have main track authority past the red signal, it can be passed in two ways. First is by permission of the train dispatcher. Second, if the dispatcher can't be reached a train can pull past the signal 100 ft and stop. This is to allow the opposing signals to 'tumble down' or go red to the next siding. After waiting 5 minutes, to allow any opposing train to encounter a red signal and take action, the train may then proceed at restricted speed to the next signal.
*I've seen in the past ABS wired like APB but without the signal at the head block being an absolute. The principle is the same, give protection to the next siding against opposing trains.
The other type of non-controlled absolute is found at tracks with hand throw switches, usually in CTC territory, where they govern entrance to the main or signalled track. The control operator (usually the dispatcher as previously noted) gives a train or engine verbal authority to enter the main track. The switch is opened. If the signal changes from stop (red) to proceed indication (for us usually yellow) the train/engine may enter the main track. If the signal does not change, block occuppied or a glitch in the circuit, the train/engine has to wait a prescribed time (currently 5 mins in ABS, 10 mins in CTC) and then may enter the main track.
tree68 LO: Here's the current NORAC Signal Chart (which you've probably already seen a version of for one railroad or another). The various aspects are explained. While there are variations by railroad, the basics are there. One condition that isn't shown there but I know is in use at least on CSX is the "G" marker on the signal mast signifying a grade. As I recall, a tonnage train (and possibly others) can pass such a signal without stopping, albeit at restricted speed.
LO: Here's the current NORAC Signal Chart (which you've probably already seen a version of for one railroad or another). The various aspects are explained. While there are variations by railroad, the basics are there.
One condition that isn't shown there but I know is in use at least on CSX is the "G" marker on the signal mast signifying a grade. As I recall, a tonnage train (and possibly others) can pass such a signal without stopping, albeit at restricted speed.
The 'G' originally only allowed tonnage trains, has defined by the specific railroads' rules as to what a tonnage train was, to pass an otherwise stop and proceed with stopping. Most signal rules now, and the note on the linked NORAC chart so indicates, the 'G' plate means all trains can observe it as a Restricting signal and pass it without stopping.
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