• Time for a new North American universal signaling system?

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by CROR410
Let's face it, Mergers & Acquisitions (M&A) are happening in North America(NA) and in a few years (10 to 20?) there will be a very small number of RRs that will run throughout NA. I would not be surprised if BNSF and CN will merge before end of 2007. This sets the stage for the flow of jobs across the border.

With todays numerous variety of signaling rules and aspects, and with the above stage, is it not time once and for all for all RRs to meet at a round table and start from scratch? I know implementing would come at a cost, but would not the long term benefit be there?

In my mind, the new system would be very logical such that anyone could look at the aspect and instantly have a very good idea what it meant with no dependency on memorization.

For example, using speed in KM cause its the only speed I know, but you get the point. :-D

COLOUR SOLID Blink(1) Blink(2) Blink(3)

Green 072 084 096 108
Yellow 036 048 060 072
Red 000(S&S) 012(S&P) 024(S&P) 036(S&P)

*S&S = Stop and Stay
*S&P = Stop and Proceed

Note a few of my thoughts:
  • #1 The solid aspects are your most restrictive.
    #2 Each blink simply adds a define amount of speed to the most restrictive, in this case 12KM. A RR could modify this.
    #3 Building on point #2, a variety of speed tables can exist to cover a variety of lines.
    #4 There can be overlap in the transisition from one color to another. So the solid yellow in this example could be used for grade signals where though the block ahead is occupied the train does not need to stop, and will still be able to stop safely should the need arise.
    #5 In the event an engineer is confused he would assume the most restrictive speed which would be the solid aspect.
The signal mast would be arranged as follows:

1st - Repeater/Distant
2nd - Block at signal
3rd - Route

Route aspect would be:
Solid Green - Primary
Solid Yellow - Secondary/siding
Solid Red - No Route (Thus #2 and #3 heads would always be R/R.)

I'm assuming many poeple would instantly argue that the system of using a number of blinks would be confusing, but I would point out the marine navigational aids around the world use a very wide set of blinks and flashes and this is well understood, easy to follow,....and almost universal too!

So there you have it. I didn't put weeks of thought into this, but I'm sure an engineering committe could listen to the needs of all the RRs and use this model to build a go forward strategy.....and remember this is only a discussion so don't flame me too much! :-D

  by Jtgshu

...........but very confusing (sorry :-)

for the most part, the very basic signal system is CLEAR - APPROACH - STOP. There are too many variables that would interfere with your system - equipment speed restrctions, train speed restrictions, track speed restrictions and limits. And specific signals allowing specific speeds don't mean anything if they aren't enforced in one way or another.

For more "specific" speeds allowed, a cab signal system with additional aspects would probably be much easier to implement. Example, Restricting - not more than 15 or 20mph, Approach - not more than 20mph or 30 mph, Approach Medium (or Limited) - not more than 30 or 45mph, and additional cab signal restrictions, allowing any speed desired, for example, for passenger, 60mph and 80mph. All the while, a clear signal would allow the MAS speed, which would be the maximum allowed speed for that stretch of track or piece of equipment.

Your system would probably work great on a confined system, like a subway or dedicated ROW and operation. But with the amount of various trains, tracks adn restrictions here, I don't see how it would work real well.

Great job though!

  by CROR410
Jtgshu, Can you give me a specific example from a RR where it would be hard to cover that using the model I presented? Include as much of a description as you can, and the speeds involved from start to finish. I'd like the challenge. :-D
CROR-------------------------------------that would loose ME and about 95% of the guys that I work with!!!!!!!!!!!!!!!!!!!!!!!!!!!! It sounds way--way to complicated. Plus where I work---the mountainous curves and dense vegatation would not be ideal for a blinking system that indicates speed---It would be like-----------Bob, what was that last signal---3 blinks or 4 blinks----Heck, I don't know!-

  by Jtgshu
Probably one of the most "modern" railroad signaling systems is here in the Northeast on the Northeast Corridor. Im not familar with the cab signal system used by the Acela, which is slightly different than other cab signal systems used on other lcoomotives adn trains. But the "high technology" is called 562 terrority (referring to teh NORAC operating rulebook rule number) and the basic definition of it is "Cab signals, no waysides"

Cab signals are far superior to fixed signals, as cab signals immediately send the trains information through the rails as to the track condition and occupancy ahead. they are based on some type of frequency being sent through the rails adn picked up by receiver bars underneith the loco. In 562 terrority, all that is there are home signals (the entrace signals to interlockings or Controlled Points) or Interlocking signals - there are no automatic signals between interlockings.

The cab signal system can give different speed allowances based on the track occupancy ahead, with much smaller blocks than fixed signals. As soon as a train ahead clears up a section of track, the cab signal immediately pops up to a better indication, or higher speed. Without cab signals, you would have to wait until the next fixed signal rolled around and was visible.

And on top of that, you might have a locomotive thats restricted to say 50 mph, or a freight car with a certain speed restriction or speed restricitons on the track due to turns, bridges, towns, RR xings and interlockings, etc, etc, etc.

And of course, all the circuity to make sure you get teh proper number of blinks for the right speeds and there seems to be much more potential for false signals and signal system screw ups, which is something which has potenially deadly consequences. In reference to the blinks in navigation, many times, navigation is line of sight, often for a long distance as well - railroads aren't like that, with trees, poles adn obstructions close to and near the ROW, along with curves and other sight blockages

Perhaps we should all learn the metric system, while we're at it? OUR signal system is much less complicated, than that which you have offered. The "big three" are the same in every book, as are most others as well. Local areas have distinct signals, but the majority of signals would be recognized, across the country, by any competent employee. Thanks for trying to "re-invent the wheel", though...................

  by LCJ
What if the signal blinks before I see it? I would then assume it hadn't blinked at all. Existing signals that flash do so continuously. I don't see a blinking code as workable.

I also don't see why the table at which all of the railroads meet has to be round. :wink:

I have to agree that there is a lot of room for standardization and uniformity -- but introducing a completely different logic is not a good idea as I see it. As signal systems have evolved over the years, they have developed by building on previous iterations and not by introducing entirely new models.

  by clearblock
It is really a moot issue. Present AAR & FRA thinking is the wayside signals will be replaced by some form of ATCS/PTC system with a computer display in the cab.

  by LCJ
Who will pay for it?

Of course, we're talking about huge outlays of capital here. Present systems are what they are now as a reflection of what the railroads are willing/able to spend for capital improvements.

Completely replacing the entire system would not, I'm thinking, provide an adequate return on investment.

As for the metric system, I believe (and I have that right!) that this is a case of backwards "us against the world" thinking. Our country remains the only significant holdout on using a system that unifies measurement practically everywhere else there is civilization. That's really something of which we can be proud! And then we wonder why we're losing our place as the science and technology leader of the world.

OK. I've said my piece.

  by slchub
On the sub I work on between Milford and Vegas, we have several blocks where the A block is just outside a tunnel and several tight curves that would preclude us from having to ability to run track speed if we had to slow to count the number of lights flashing vs. a flasher or solid yellow or red.

Give a guy a centimeter, and he'll take a kilometer............. :P

  by LCJ
Did you think of that when you were inching your way into the yard? Or was the conductor dragging his feet as he pounded the ballast hoping for a cup of coffee?

  by CROR410
The wife is watching TV, and the baby is finally sleeping so I can finally provide a few replies. :-D

Regarding the blinking:
3 blinks can happen in a second or a little more. If you don't currently miss the eclipse in a regularlly flashing signal, you won't miss three or less blinks....and they would repeat....for example 1.5 seconds of light followed with 1.5 seconds containing 3 blinks..... for example. If you have enough time to determine that a signal is flashing you will have enought time to tell that its blinking. You would not have to slow down or 'try to remember what you just saw'. LED based lamps which now making 'inroads' in the signaling lamps produce very rapid light ramp-up ramp-down speeds....thus producing a very 'sharp' transisition in intendity versus a softer transisition with incadescant bulbs.

With regards to marine navigation....line of sight in not always guarenteed. In rough seas with high swells, there are moments when the buoy, and ship line of sight is blocked by a wave. Yet despite this mariners are quite able to determine the 'aspect' as being displayed.
Last edited by CROR410 on Wed Jun 28, 2006 8:34 pm, edited 1 time in total.

  by CROR410
LCJ wrote:Of course, we're talking about huge outlays of capital here. Present systems are what they are now as a reflection of what the railroads are willing/able to spend for capital improvements.

Completely replacing the entire system would not, I'm thinking, provide an adequate return on investment.
The entire system would not have to be replaced. Only the reprogramming of the aspects. In microprocessor based controller this should be easy, but does come with costs of course. I do acknowledge that one cost factor is the requirement to have always 2 heads and in many cases three heads, where maybe 1 or 2 sufficed before.

  by CROR410
GOLDEN-ARM wrote:OUR signal system is much less complicated, than that which you have offered...... Thanks for trying to "re-invent the wheel", though.
What is so complicated about it? You have three speeds, one each associated with each color, R, Y, G. A blink is defined with an additional amount of speed.

Green = 30MPH, thus 1, 2, 3 blinks could be:
30+10=40, 30+10+10=50, 30+10+10+10=60

1st head is the head that tells you what to do now, the 2nd head tells you what to expect at the next signal, what you need to be doing by the time you reach the next signal (or milepost, end of interlocking, etc). 3rd (optional) head is used to indicate if the train will be proceeding on the main track, or turning out onto a 'secondary' track, i,e turnout, etc.

I acknowledge that it could be hard to cover every possible signal scenario in North America, and maybe a few additional unique signals will be needed, but at least the majority of the rules will be covered by one common set of aspects.

Remember the speed 'table' I have listed are only examples. What I am trying to convey is a model that while very logical and uniform does allow each RR to 'tweak' the speeds for their particular needs. But Y/Y is always Y/Y is always Y/Y regardless of the RR you are running on.

This next part is going to sounds crazy, but I think there will be a time when train engineers will be like airline pilots. They will run/fly in different territory on a regular basis, each territory will some unique rules, and the engineer/pilot will be qualified to run/fly in the different territories. The differences in some signaling aspects could prove deadly. But then again, newer forms of signaling and automated train control (i.e driverless trains) could likely eliminate wayside signaling in North America.

You're welcome! :-D