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Are the swtiches in modern railroad yards controlled by wired connections or wireless connections? (Are some stil set only by hand - directly or with cables ?)
And what about the controls of locomotives when they are chained together? Does some sort of wiring harness connect them?
As for locomotives when they are coupled together they use what is called an "MU" cable. MU stands for multiple unit. So the locomotives are set up for either "Lead or Trail" Lead being as it sounds it will be the first locomotive. Trail applies to every locomotive following. However there might be five locomotives and only two are working. It could even be only the lead unit. The others are isolated and don't respond to the lead unit actions. This is of course different than when you see locomotives in the middle or at the rear of a train. These are DP or Distributed Power units. They are connected in a wireless link to the lead unit. This is a great benefit in train handling. With trains getting longer this helps with train control. Lengths can easily be over 10,000 feet. Coal trains aren't as long but their weight can be as high as 19,000 tons total.
Switches, major yards control the switches from a control tower in hump yards. I am sure it may be different on other rail lines but our big yards use wired control. With hundreds of switches the most reliable control is wired. Main line CTC track switches are primarily wireless from one main dispatch centers. All automated switches can be manually operated with a specific procedure being followed to do this. I don't know if this answers your questions completely.
Thank you. That was a very comprehensive answer.Quote:
Originally Posted by Ronald Blue
I was watching the old film "The Train", in which a WW II era railyard control tower appears to use switches controlled by cables. It made me wonder about the modern set-up.
Interlocking towers had manual control of switches. As a child one of my fondest memories was going over to Boylan
Tower and watch one man control trains on three different rail roads. Instead of cables, most switches were controlled by shafts, connected to the control tower. He would pull on a huge lever to change switch position . Switches farther out were electric, controlled by those wires strung along the railroad right of way. Western Union / telephone were on one side of track and signal / switch control were on the other. In some locations, you have what are called "rubber switches, which allow trains in one direction to pass thru, without switch being aligned to direction of travel. Flanges on wheels force switch to open. But trains going in other direction need to have switch aligned
Many switches outside of rail yards and commuter rail are still manually operated
That's probably true on some railroads Lee. With over 30,000 miles of track in our system at least 25,000 are automated. All CTC (Centralized Track Control) track is automated. Most of our tracks are CTC. Single main TWC (Track Warrant Control) track usually has CTC islands that allow trains to be ran in and out of sidings without them having to stop to throw switches unless traffic volume is low. Double main TWC track also has these CTC islands that allow dispatcher controlled run arounds etc. The TWC double main does have some manual crossovers but they are rarely used. If it's because of a maintenance window they usually assign switch tenders to handle the switch operation. The double track CTC lines have high speed crossovers that allow 40 MPH crossover moves in many places. That might not seem like a big thing but when you slow a train to below 10 MPH for the length of the train and it's more than 2 miles in length that is a significant delay. We do have some track that is still "dark" unsignaled and has manual switches. But it's not common on our railroad.
Steve and Ron, thank you both for the question and the answer. I am always impressed by the diverse knowledge available here, especially on subjects about which i never thought, but find fascinating and educational when raised. I hope to learn something new every day, and today that has happened. Thank you guys. Patrick
Can I piggyback a question here? The Miami Airport has an automated tram that has no driver. It goes back and forth all day and I'm sure there are multiple backups to the system that tells it when and where to stop, but my question is, how safe am I on this thing? Every time I ride it, which is a lot, I ask myself, "What if something fails and this thing doesn't stop?"
I feel like I'm trusting my life to electronics. I was on an Airbus once and the pilot told us that they had "lost two of the computers that control the aircraft." Now, I know about these planes, and that means it was on the third and FINAL backup, which is a hydraulic system that is the last resort. Had it broken, we would have fallen from the sky. We had to do the whole crash preparedness thing and put our heads between our legs (save the joke, but that too) and prepare for a possible crash when we landed. We landed fine- it was more precaution than anything. I can't help but think of this when I ride that automated train.
There have been a few accidents with the people mover at MIA in 2008 and 2012. I think both were due to lax or improper maintenance by airport contractors.
https://en.wikipedia.org/wiki/MIA_Mover
That said, I'd certainly trust an automated metro system over other drivers when I'm in my car.
Well there ya go- This is exactly why I only take it when absolutely nescessary. As for trusting other drivers, you have a good point.Quote:
Originally Posted by Peter Kelly
I can't think of too many other large airports that don't have an driver-less train system these days. I think most of these are remotely monitored so humans can intervene if necessary.
Kinda like the cockpit of the future. It will have both a pilot and a dog in it. Pilot is to feed the dog, and dog is to bite the pilot if he touches anything.