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TheSubwayStation

Using station time instead of grade time

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When it was determined that the blocks of track (distances between signals) in some cases were not long enough to allow trains to stop before a rear end collision would happen, there were basically two solutions enacted to fix the problem: 1. lengthen the blocks, or re-program the signals to keep a two-block distance between trains instead of a one-block distance. 2. add grade timers.

 

The problem is that the first solution reduces capacity by forcing trains to run farther apart, and the second solution slows down the trains and as a result, slightly reduces capacity too. I've been thinking of a new solution that would, if I'm correct, eliminate both problems while preventing crashes. I would double the control length of the signals (there would be two full blocks of red signals behind each train instead of one) but use station time to allow trains to pass the first red signal at a safe speed.

 

Thus, trains would only have to slow down if they approached the train ahead of them, unlike with grade time, which forces them to slow down unconditionally. (And, unlike if the control length was doubled, trains would still be able to close in on the train ahead of them, they'd just have to do so at a safe speed.)

 

This diagram hopefully makes the solutions clearer:

 

Existing setup (risk of collision):

 

TRAIN BEHIND-----------GREEN-----------YELLOW-----------RED-----------RED-TRAIN AHEAD

 

Example of grade time solution (trains unconditionally slow down):

 

TRAIN BEHIND-----------GT35-------------GT35---------------RED-----------RED-TRAIN AHEAD

 

Example of doubling the control length:

 

TRAIN BEHIND-----------YELLOW----------RED---------------RED-----------RED-TRAIN AHEAD

 

Example of my station time solution:

 

TRAIN BEHIND-----------YELLOW----------ST25--------------RED-----------RED-TRAIN AHEAD

 

 

I'm not a signal expert, so I don't know for sure whether my solution would be a good one. I also don't know if it's already been implemented in certain places in the system. What do you guys think of it?

 

(By the way, if my post was confusing to anyone, I'll be happy to try to explain it more clearly.)

Edited by TheSubwayStation
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Station Time is already what you describe. Grade Time has nothing to do with a train ahead; It's for grades or curves. When a train is ahead in these areas, then often, the grade time changes in to station time, if so equipped.

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Station Time is already what you describe. Grade Time has nothing to do with a train ahead; It's for grades or curves. When a train is ahead in these areas, then often, the grade time changes in to station time, if so equipped.

 

I don't think you understand what I'm talking about. I know that grade time doesn't have anything to do with the train ahead, but my point is that it's often used to slow down trains to reduce stopping distances (and thus prevent rear-end collisions). My solution uses station time to allow the control length to be extended without keeping trains from closing in on each other. This would hopefully reduce the need for grade timers because trains would only be able to get closer to each other at a safe speed.

 

Essentially, this is a proposal to expand increased control lengths + station time to more parts of the system to reduce the need for grade time.

Edited by TheSubwayStation

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The existing control lengths of 1+ full clear signal block are sufficient to protect the rear of trains from their followers while minimizing delays. Station time allows trains to creep up within the one block buffer, provided they demonstrate safe speed prior to doing so.

 

What you propose will necessarily lengthen headways, or result in delays.

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The existing control lengths of 1+ full clear signal block are sufficient to protect the rear of trains from their followers while minimizing delays.

Okay; I brought up this topic under the assumption that they weren't, in some cases (at least before a multitude of grade timers were installed).

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I have somewhat of a related question. When, if ever, is an automatic key by allowed at an automatic signal? Because this seems analogous to a stop-and-proceed signal that some RR s have, and it helps solve the problem of both safety and maintaining good headway.

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Only on non-revenue track, such as yard leads; and on mainline track, only where designated by an "AK" sign. One place you see those is coming into Stillwell on most tracks. Some wrong-rail moves as well.

 

They used to be allowed everywhere, but the problem was, T/O's weren't following the restricted speed extreme caution rule that came along with it and were having collisions; so they banned it except for those two cases, or receiving on-the-spot permission from supervision.

Edited by Eric B
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When it was determined that the blocks of track (distances between signals) in some cases were not long enough to allow trains to stop before a rear end collision would happen, there were basically two solutions enacted to fix the problem: 1. lengthen the blocks, or re-program the signals to keep a two-block distance between trains instead of a one-block distance. 2. add grade timers.

 

The problem is that the first solution reduces capacity by forcing trains to run farther apart, and the second solution slows down the trains and as a result, slightly reduces capacity too. I've been thinking of a new solution that would, if I'm correct, eliminate both problems while preventing crashes. I would double the control length of the signals (there would be two full blocks of red signals behind each train instead of one) but use station time to allow trains to pass the first red signal at a safe speed.

 

Thus, trains would only have to slow down if they approached the train ahead of them, unlike with grade time, which forces them to slow down unconditionally. (And, unlike if the control length was doubled, trains would still be able to close in on the train ahead of them, they'd just have to do so at a safe speed.)

 

This diagram hopefully makes the solutions clearer:

 

Existing setup (risk of collision):

 

TRAIN BEHIND-----------GREEN-----------YELLOW-----------RED-----------RED-TRAIN AHEAD

 

Example of grade time solution (trains unconditionally slow down):

 

TRAIN BEHIND-----------GT35-------------GT35---------------RED-----------RED-TRAIN AHEAD

 

Example of doubling the control length:

 

TRAIN BEHIND-----------YELLOW----------RED---------------RED-----------RED-TRAIN AHEAD

 

Example of my station time solution:

 

TRAIN BEHIND-----------YELLOW----------ST25--------------RED-----------RED-TRAIN AHEAD

 

 

I'm not a signal expert, so I don't know for sure whether my solution would be a good one. I also don't know if it's already been implemented in certain places in the system. What do you guys think of it?

 

(By the way, if my post was confusing to anyone, I'll be happy to try to explain it more clearly.)

 

 

I'm not a signal expert either, but my impression is that all three approaches are used, depending on the exact situation at each signal.

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Essentially, this is a proposal to expand increased control lengths + station time to more parts of the system to reduce the need for grade time.

 

Actually if you can ever see Queens Plaza area you may see something like that in one of your examples..

Edited by RTOMan

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I guess his idea reads like this...

 

Instead of having a GT25 going across the MannyB end to end, no timers but increasing the amount of reds (on the bridge depending on the location its one to three) between my train and a possible train in front, with exhibiting train control will clear some of the reds, even with no station nearby.

 

So...

 

If I'm the only train on the bridge, I see nothing but greens... wrap it around all the way up and down and into Grand, but probably would have to take brake at the portal as I would hit the portal at over 60mph and derail on the curve. Grade time would have to remain for the curve but only at the curve and in the signal or two following and preceeding to ensure the entire train rounds it at a safe speed (which IMO is 30mph, not 25 like posted now). But I would be able to get over 40 on the downgrade before slowing to safely go around the curve instead of the constant 23 I do now...

 

If there was a train in front of me in Grand, same idea going up and down, but in this case I wouldn't see any grade time near the curve, just four reds (can't see the other three, just the first one before the curve) that probably would start at the portal for sufficient stopping distance. Train control would allow me to close in and finally stop one signal block away. I would still get across the bridge faster than if I maintained that 23 the entire way.

 

Now that's just a very specific example for the Manny, it could probably be repeated on the Willy. In river tubes, instead of GT going downhill, just wrap and increase the amount of following distance (red) if a train was there (most tubes now have two yellows and/or two reds if a train ahead). Again, with a train there, train control begins to clear some of those reds.

 

To TSS: Your main problem was calling it "station time" I guess based on the "clear a red with proper speed (that proper speed decreasing the closer you get)". It is not station time, which is only around just preceeding stations. Since this is a new idea, you should have branded it differently... something like "approach time (AT)" comes to mind. Problem is, one would have to relabel all the signals in the system as AT would be different depending on the area.

Edited by TwoTimer
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I guess his idea reads like this...

 

Instead of having a GT25 going across the MannyB end to end, no timers but increasing the amount of reds (on the bridge depending on the location its one to three) between my train and a possible train in front, with exhibiting train control will clear some of the reds, even with no station nearby.

 

So...

 

If I'm the only train on the bridge, I see nothing but greens... wrap it around all the way up and down and into Grand, but probably would have to take brake at the portal as I would hit the portal at over 60mph and derail on the curve. Grade time would have to remain for the curve but only at the curve and in the signal or two following and preceeding to ensure the entire train rounds it at a safe speed (which IMO is 30mph, not 25 like posted now). But I would be able to get over 40 on the downgrade before slowing to safely go around the curve instead of the constant 23 I do now...

 

If there was a train in front of me in Grand, same idea going up and down, but in this case I wouldn't see any grade time near the curve, just four reds (can't see the other three, just the first one before the curve) that probably would start at the portal for sufficient stopping distance. Train control would allow me to close in and finally stop one signal block away. I would still get across the bridge faster than if I maintained that 23 the entire way.

 

Now that's just a very specific example for the Manny, it could probably be repeated on the Willy. In river tubes, instead of GT going downhill, just wrap and increase the amount of following distance (red) if a train was there (most tubes now have two yellows and/or two reds if a train ahead). Again, with a train there, train control begins to clear some of those reds.

 

To TSS: Your main problem was calling it "station time" I guess based on the "clear a red with proper speed (that proper speed decreasing the closer you get)". It is not station time, which is only around just preceeding stations. Since this is a new idea, you should have branded it differently... something like "approach time (AT)" comes to mind. Problem is, one would have to relabel all the signals in the system as AT would be different depending on the area.

 

 

This seems like a sound approach, actually. Though very very complicated.

Complicated enough that "Why not just modernize all the rolling stock and go full CBTC" isn't that crazy of an alternative.

 

Although It's still a crazy alternative. I feel like they wouldn't implement a new timer system when they want to get something more modern going, even if that's decades away from being system wide.

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I mean this is not my idea or what I would do, this is just my plain language interpetation of his idea based on my knowledge of the signal block system. What was missing in his explanation is that not all grade timers regulate speed on... well... grades. Some regulate speed on curves, others on switches, still others try to prevent station or home signal overruns. These others must remain. The reason they were put there in the first place is because... of course... people didn't obey them and threw passengers about the train while disobeying speed limits on curves/switches. If people did follow speed limits whenever the train wasn't going physically straight, then those timers never would have been installed. In many places the old speed limit sign is still posted in areas where timers were added. Remember, TA is reactive, not proactive (when it comes to train control).

Edited by TwoTimer

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I don't think you understand what I'm talking about. I know that grade time doesn't have anything to do with the train ahead, but my point is that it's often used to slow down trains to reduce stopping distances (and thus prevent rear-end collisions). My solution uses station time to allow the control length to be extended without keeping trains from closing in on each other. This would hopefully reduce the need for grade timers because trains would only be able to get closer to each other at a safe speed.

 

Essentially, this is a proposal to expand increased control lengths + station time to more parts of the system to reduce the need for grade time.

 

Station Time, by design, allows one train to close in on another train sitting in or moving out of a station. Station Time, when in effect, usually forces the Train Operator to comply by significantly slowing his train. Quite honestly, unless there's a wheel detector system activated there isn't anything to stop the Train Operator from taking full power once he's cleared a signal. The most important factor in Train Operation is the Train Operator's operation.

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