zugmannI've done moves where you pull into a yard, a yard crew (which PSR/some style management doesn't like) - grabs onto your rear end set out - a utility (again, PSR and certain managers hate these) then moves and rehangs the marker and launches you out on your way.
So, how does this square with PTB?
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...
And Greyhounds, pickup in Ceder Rapids is simple with your concept
The through train from Omaha stops for a few minutes while the Ceder Rapids power has the switch benind the train thrown, couples on to the end of the train, with the former Fred de-activated and the one at the end of the Ceder Rapis block activated, and the Ceder Rapids power is the distributed power to Chicago.
Is there any location on the North American rail system where moving blocks have been applied?
greyhoundsIs this a fantasy? Oh, maybe. But with the communications tech we have today, and what we will develop in the future, who knows. It could happen.
I've done moves where you pull into a yard, a yard crew (which PSR/some style management doesn't like) - grabs onto your rear end set out - a utility (again, PSR and certain managers hate these) then moves and rehangs the marker and launches you out on your way.
Can even do the opposite for a pickup, or a modified way to do both.
Is a really quick process - road train takes a couple minute pause - and everything is on its way. It's amazing what (and how fast) you can do when you have a couple decent yard crews or utilities, and aren't relying on a 23,000 foot train to do all its work by itself.
All the electronic nannies and toys aren't going to replace a pair of boots on the ground. Period. That's the fantasy.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Lithonia OperatorTechnical folks and current railroaders certainly would understand much more, but I'm not surprised to hear you say some of it was inaccurate.
Frustration, thy acronym is P - T - C.
jeffhergert I was not impressed with the article. There were things that the author didn't get quite right in current PTC operation and some of the subsystems that we have.
I was not impressed with the article. There were things that the author didn't get quite right in current PTC operation and some of the subsystems that we have.
I enjoyed reading it. But there were several places were he stated X will mean Y. Or A will facilitate B. And my brain was like "well, you're saying that, but you're not showing me." So I had no idea how much of value was really there. Seemed like generalities/suppositions/predictions, but not a lot of clues to help someone like me to understand. Technical folks and current railroaders certainly would understand much more, but I'm not surprised to hear you say some of it was inaccurate.
jeffhergert I'm not sure that going to moving rather than fixed point boundaries will make that big of difference.
I would opine that the place moving blocks will make a difference is on heavily used lines, where the reduced headway between trains will increase capacity.
For simplicity's sake, moving blocks would be a lot like driving your car - you hopefully leave a suitable space between you and the car ahead. As the speed goes up, so does the distance.
OTOH, if you are the only car in sight, your speed is governed by the posted speed limit and the abilities of your vehicle.
If you watch the various train cams around the country, you'll rarely see two trains on short headway. More often, they are an hour and more apart in any given direction. On a single track line, sans fleeting, rolling blocks would make virtually no difference.
I was not impressed with the article. There were things that the author didn't get quite right in current PTC operation and some of the subsystems that we have. I'd have to get out the article for specifics.
The theory is that rolling/moving blocks allow trains to run on closer headways. That the point of where authority to move ends will be at (or more likely close behind) the end of the train ahead, instead of a fixed signal boundary point. The moving boundary is going going to be continuously calculated, including the changing braking distance to the end point. I'm not sure that going to moving rather than fixed point boundaries will make that big of difference. I think it will cost more to get that capability than possible savings from closer headways will actually save them.
Jeff
caldreamerThe higher priority train is moving north and lower priority train is heading south. Why hold the lower priority train once the rear of the higher priority train has cleared the switch and is proceeding north?
What Balt was describing is a different situation entirely, looking at the other end of the siding with both trains proceeding the same way. In an absolute-block system, the lower-priority train would have to remain in clear until the higher-priority train completely cleared the block past the end of the siding -- only at that point could it start more than a little acceleration. CBTC can be arranged to gauge the actual separation based on speed and acceleration as well as default physical distance, so what happens is that the switch traverses and the lower-priority train can proceed with 'as much dispatch as it can muster' just as if it were entering a clear block, until the speed of the lower and higher priority trains become equal.
In practice there would be some leeway allowed for emergency braking or catastrophic derailment of the 'high-priority' train in the example, more of course if the 'continuous' were in some sense functionally intermittent in speed tracking, or some of the NAJPTC engineers left the food-service industry for another try at train control and forgot about tracking the back end speed as well as the front.
But for slowly-accelerating coal trains trying to save fuel, being able to start rolling up to hopefully-sustainable track speed early is a meaningful time saver. And once that train is up to track speed, its inertia will likely help it on even an undulating profile to maintain 'one-speed' reasonably, so following trains will be less 'stabbed' by the required wait to clear the absolute block behind an accelerating coal train if they know where it is and how it is changing speed...
caldreamerThe higher priority train is moving north and lower priority train is heading south. Why hold the lower priority train once the rear of ther higher priority train has cleared the switch and is proceeding north?
Trains being OVERTAKEN are moving in the same direction. Trains that MEET are moving in opposite directions.
Never too old to have a happy childhood!
The higher priority train is moving north and lower priority train is heading south. Why hold the lower priority train once the rear of ther higher priority train has cleared the switch and is proceeding north?
One thing that gets overlooked by many in the operation trains in signalled territory.
When a train is Overtaken by a higher priority train, it will not leave the siding immediately after the priority train has passed - to do so would have the train leaving the siding operating under the requirements of a Restricted Proceed signal indication - operating at 20 MPH or less and WITHIN 1/2 the range of vision looking out for a train or other obstruction ahead until they get a more permissive signal indication at the next signal.
Normally the overtaken train will wait until they get some form of a Approach indication, that permits them to operate at 1/2 the maximum authorized speed not exceeing 30 MPH and being prepared to stop at the next signal. The Approach form of signal indication tells the overtaken train there is NO TRAIN or obstruction between it and the next signal - a much 'easier' operating condition.
To get a Clear indication there must be at least TWO (and in some systems more) signal blocks between the two trains. Once upon a time signals were spaced at a nominal mile or so; when the carriers started operating larger trains they began spacing signals at a nominal two mile distance, in the 21st Century the signal spacing has been extended to a nominal three miles between signals - the spacing is to allow for nominal, non-emergency, braking distance. PTC enforced braking distances may be longer.
It does have the ring of a solution in search of a problem.
Lithonia OperatorThe "After PTC" article in the Feb Trains is interesting. But ... It states that moving blocks would be very beneficial to unit coal trains, whereas intermodal trains do just fine with the current fixed-block system. Why the heck would that be? Why does the type of freight matter? Is it because a long coal train is slower and more prone to delays, while an intermodal train's pace is more predictable? That's all I can think of; and I'm not sure what I just said about those two train types is even true.
It states that moving blocks would be very beneficial to unit coal trains, whereas intermodal trains do just fine with the current fixed-block system.
Why the heck would that be? Why does the type of freight matter?
Is it because a long coal train is slower and more prone to delays, while an intermodal train's pace is more predictable? That's all I can think of; and I'm not sure what I just said about those two train types is even true.
Intermodals are already given preference in Dispatching - ie. getting lesser priority trains in the clear to allow the Priority trains to be operating on clear signals. Lower priority trains, in many case are operating on less than clear signal indication. Rolling 'blocks' would give the lower priority trains to operate more frequently on 'clear blocks'. At least that is the theory. In actual practice??????
The "After PTC" article in the Feb Trains is interesting. But ...
Still in training.
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