Why Cold Weather Wreaks Havoc on Trains

A comment from a friend who grew up in Russia:

Never heard of cancellations on the Trans-Siberian due to cold weather. Wiring is kept under constant tension by weights through pulleys there, so if wires get shorter, the wights just raise up, then go back down again when it gets warmer. There are special de-icing pantographs that vibrate and kick the ice off, etc.

Click to expand...

The catenary system in most of Europe and the New England Devision is Constant Tension Catenary, which (as you stated) uses a system of weights and pulleys to keep the wire at a (you guessed it) constant tension. The MAD-North (Mid Atlantic Devision - North) section of Amtrak which runs from New York, to Baltimore, and out to Harrisburg uses Fixed Tension Catenary. Most of the catenary was installed in the early to mid-1930's, before Constant Tension was invented. In fact, throughout the Harrisburg territory much of the catenary is actually the original wire that was strung in 1932, or thereabout. To replace it with Constant Tension would be a very expensive ordeal spanning 10+ years and wouldn't even be possible in locations such as Gap, PA.

When there is ice accumulating on the catenary, the dispatchers will issue a Double Pantograph Order which takes care of much of the problem; it is only in the absolute worst icing conditions that it won't work. Which, to be honest, only happens when it's too cold to actually run any of the electric motors anyway, especially the new Siemens.

There's also the ice accumulating on the rails that can be troublesome for running trains. All of the interlockings have heater stations to deal with the ice and snow, but the 10+ miles stretches between interlockings can (and have) accumulate enough ice to actually derail a train. Plus, when you get into low-grade railroad territories (i.e. Conewago) you have small avalanches that completely bury the tracks and cover any potential hazards, such as boulders.

I guess what I'm getting at is that there are a lot of issues that come along with winter weather on the railroad and with the cutbacks congress is forcing on Amtrak, it's not going to get any better anytime soon.

I completely forgot to include that icicles will often blow parts of the catenary apart, or destroy overgrade bridges and tunnels. So, that's yet one more thing that cold weather can do to delay trains.

Plus, when it's cold the workers are less likely to come in on their day off to fix an issue. Sometimes, if the weather is bad enough and not enough people are willing to come in, downed wire and broken equipment can sit an entire weekend before it gets fixed.

Why can't constant-tension catenary be installed in Gap, PA?

The freeze damaged equipment is another factor. Certain trains do not enter indoor facilities after every trip and don't have time to defrost. Ultimately, the equipment fails.

Thirdrail7 said:

The freeze damaged equipment is another factor. Certain trains do not enter indoor facilities after every trip and don't have time to defrost. Ultimately, the equipment fails.

Click to expand...

Well then, it sounds like they just need to extend their routes further south until the entire consist thaws and can return safely to service!

MattW, I see that you're in Atlanta, so I don't know if you've ever had the chance to see the Box Catenary in Gap, Pennsylvania. I wish I had a picture handy, maybe I'll try to scrounge one up when I get into to work later this week. Gap has what we refer to as Gap Curve, which is a very sharp curve on a steep angle. Most railroad locations in the south, the midwest, and New England have the bonus of having been in built on flat land and at a much later time than in and around Pennsylvania. As such, most railroad locations can run in mostly straight lines. Unfortunately for Pennsylvania, Delaware, Maryland, New York, and New Jersey the railroad was built at a time that blasting straight lines through a mountain wasn't feasible. So, we have locations such as Horseshoes Curve (several miles west of Harrisburg) so called because of its shape, or Gap Curve, which is so steep you can see all four sides of the house that sits on the inside of the curve (little bit of trivia for ya there).

The catenary at Gap had to be constructed in an entirely new and innovative way so as to follow the steep curve. What the engineers of the 1930's came up with is called Box Catenary. It is the normal 3 wires (Auxiliary, Messenger, and Catenary) but in a 3 dimensional triangular shape. It's the only possible way to have the catenary follow the curve so closely without having Cat Poles (Catenary Poles) every 20 feet. Given that Constant Tension Catenary only utilizes Messenger and Catenary wire, the triangular shape isn't possible.

Long winded, I know, but it's one of the many reasons that it'll be a long time before we see true high-speed rail in most of the north east.

There is no technical reason that constant-tension catenary could not be installed through Gap. It is a matter of appropriate placement of support structures and the anchorage weights. The horizontal and vertical curves and the grades are parameters in the design process. Unlike the PRR fixed catenary that follows the curve, constant tension is a series of chords. Sharp curves require lots of structures (reference the New Haven to Boston section along Long Island Sound), but it certainly can be done.

PRR 60 said:

There is no technical reason that constant-tension catenary could not be installed through Gap. It is a matter of appropriate placement of support structures and the anchorage weights. The horizontal and vertical curves and the grades are parameters in the design process. Unlike the PRR fixed catenary that follows the curve, constant tension is a series of chords. Sharp curves require lots of structures (reference the New Haven to Boston section along Long Island Sound), but it certainly can be done.

Click to expand...

For an extreme example see the new catenary at New London station! Lots of metal suspended in the sky!
Bottom line is finding the money to do it, as always.