According to the news this evening, Amtrak suspended service form NYC to Albany today due to frozen switches and signals. I wonder if this is a common occurrence. If so, then perhaps there’s a new piece to add to our winter operating sessions. [:)]
I knew switches could freeze, I didn’t know that signals could. Septa has a problem with switches freezing in extreme weather all the time. Never heard them reporting frozen signals!
Frozen signals sounds like a news reporter in way over his or her head when reporting something. Frozen switches happen all the time in colder climates, but frozen signals ? The only thing about a signal that could freeze would be the battery that powers them.
I can’t say for sue this is what happened, but many signals still use relays at trackside. Extreme cold weather, condensation and rain/snow can effect reays even in enclosures.
Years ago as an electrician, I saw lots of relays indoors affected by poor environmental conditions. For these resons highway traffic signal controllers have been solid state PLC’s for decades. But railroad signal systems, especially on the northeast corridor, are still largely what was left by the PRR, B&O, NYNH&H and NYC - relays and 1930’s track circuits.
Sheldon
Moisture and condensation on electrical contacts and motor comutators and brush holders freezes and causes the contacts to lose contact and keep brushes from contacting comutators in the motors. Some locations have electro psnumatic switches which operate with compressed air. There are tiny passages in the control valves that ice up and prevent air flow to the switch machines. Condensation in the machines may freeze on the rods and bars in the machines and prevent them from moving. The electric or gas heaters at switch locations are there to melt snow and ice in the points and do very little to keep the switch machines warm. Many times I had to put a 25 watt light bulb inside switch motors to keep the moisture from freezing. I have never had or heard of a signal relay freezing. Relays are sealed and unless the glass or plastic case is broken moisture can’t get inside.
i know the railroads no longer have the manpower to maintain things the way they used to, but, isn’t it sad how an all weather transportation system has degenerated in to what it is today.
we used to pay yard clerks time and a half to clean switches when the track men were overwhelmed. anything to keep the plant working and trains running. we thought nothing of loading up several tons of bagged salt on a caboose and running the mow guys up and down the lead to salt the switches so we could keep working.
none of this was regarded as heroics at the time. it was just what was necessary to keep the railroad running. oh well, so much for an old man living in a young man’s world.
grizlump
What may be happening is snow or ice prevents the switch from closing completely. Because now the switch points are stuck partly open, obviously the signal is interlocked to stay red to prevent a derailment. So, the train is delayed by a pesky red signal, which is actually working perfectly.
Having said that, though, it may also be that the circuitry in the local signal bungalow needs a little more warmth. A new CTC installation about 1981 in the Toronto area had occasional problems on bitter nights. When the signal maintainer responded to the call his body heat inside the bungalow would often be enough to make the problem disappear as if by magic. Once they realised what was happening small heaters were installed.
John
Actually I think the cold weather response is better now than it has been. There are more resources and automated systems (switch heaters, back up generators, etc) than there were years ago.
Wouldn’t the salt jam in the switches and make them harder to line and throw? Doing that on a main line would be an issue since it would short out the signal systems, but on lead there probably aren’t any track circuits.
Some signals have relays in the head units (searchlights) that could freeze and the relays are not sealed. They have vent screens in the bottom. I worked signal construction and maintenance in the Midwest (IN, OH, MI, PA, NY and IL) and freezing was seldom a problem but it did happen. The newer bungalows have heaters and older ones are often retrofitted. Electric powered switches can freeze if they are not kept properly lubed and if seals aren’t maintained.Also, ice (frost) can form on contacts which stops movement on a switch machine or prevents the proper electrical contact in a shelf-mounted or plug-in relay.
[8-|]
“Wouldn’t the salt jam in the switches and make them harder to line and throw? Doing that on a main line would be an issue since it would short out the signal systems, but on lead there probably aren’t any track circuits.”
the whole idea was to make it safe for the switchmen to be able to line the switches and pull the pins without falling on thier cans. a little salt gives added traction and keeps the ground a bit slushy instead of slick as glass. it is best thrown along the pathway beside the lead and around the switch stands. the company used to hand out ice creepers for anyone working outside in freezing rain or sleet.
grizlump
the answers so far have mostly covered the fact that signals can freeze up - if only indirectly… It would be interesting to know what is done to resolve the situation when it happens please.
I guess that there are at least two situations that have to be dealt with -
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when the track is plain or the switches are set correctly but the signal equipment/circuit has failed.
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when a switch or switches have either not closed correctly or not proved closed correctly.
Thanks
[8D]
You fix it. You warm the switches and clean them. You clean the signal equipment.
Pretty much ! You clean the ice off contacts and out of the machine (if inside the mechanism) and repair or replace the seals (gaskets). If ice is blocking the points, you clear it out or if the switch heater has failed, you repair it so it can clear out the ice and snow. [8-|]
In the winter we would carry a broom inside the cab and caboose so we could clean out the snow on the points.For frozen locks,foot lock and handle a fusee would work wonders.
Of course this whole discussion hinges on the how accurate the news report is and the assumption that if the signal system did have problems and that this is common throughout the US.
I would say that the signal system failing due to cold weather isn’t that common. Ice storms are much worse (bringing down power and signal lines). It is more likely that the signal problems were actually red blocks caused by the switches being frozen up or snow packed.
Also realizing that Amtrak cancelling service doesn’t mean the LINE is out of service, it just means they stopped running passenger trains. They could very well still be running freight trains. Amtrak may have not wanted to incur the delays and passenger complaints by running trains hours late.