GG1 Washington DC runaway

[Davy]

Didn't GG1's and Pennsy passenger cars have manual brake systems?  Wouldn't this have prevented the runaway into the Washington DC Union Station (early 50's)?

[ebtnut]

It's been a while since I read up on this accident, but my recollection is that the train had either added or dropped cars (probably mail/express) earlier in the run.  The brakeman forgot to cut in the air to the rest of the train before departure.  Speeds near 100 mph were not uncommon on the Baltimore-DC stretch, and the train was going fast.  So fast that when the engineer applied the brakes, only the engine and maybe one or two head-end cars had brakes.  The weight and momentum of the train carried it right through the bumping post and into Union Station.  It may have only been going at 20-25 mph at impact, but 1000 tons going that fast is not going to stop on a dime.

[Davy]

From what I read, they had about five or six minutes' warning, enough to get everybody off the concourse.  It seems like plenty of time to enlist crew and passengers to crank down the brakewheels.  I admit, I'm not familiar with how well this works to stop locos/cars, but it sure seems worth the effort, even if it only slowed the speed by ten or 15 mph.

[scottychaos]

I always thought that railroad air brakes were ON (brakes applied) unless the cars were hooked up to the train's air line, then the pressurized air would open the brakes (brakes not applied) and the train could roll..

that way, if there is a derailment or the train somehow breaks in half, the air line is ruptured, no pressurized air to keep the brakes "off" and the brakes are automatically applied..

opposite of an automobile..
with your car, brakes are off by default unless pressure is applied (by pressing the brake pedal)
with railroad cars, brakes are ON by default unless air pressure is applied to turn them off...

So if most of the train (in the GG1 example) was not hooked up to the locomotive's air line, shouldnt the brakes have all been ON (brakes applied) on those cars?

Scot

[jayl1]

Speaking of GG1 wrecks - there is a new book out - The Derailment of the Congressional Limited in Philadelphia, PA - pulled by GG1 #4930 on Labor Day weekend - 1943..

[Atlantic Central]

Without explaining every working detail of the Westinghouse Air Brake, it is possible to lock the brakes in the released position ebtnut discribed.

Most passenger cars of that era had hand brake ratchet levers in the vestibule and retainer valves that could be released to set the brakes, but the fact that a number of cars where not connected to the trainline was most likely not discovered until after the crash.

The warning time was simply that the engineer could tell the train was not responding properly, but it is likely no one on the train knew why at that moment. Six, seven or even ten minutes is not very long at 60, 70 or 100 mph.

And, that is correct too, from Washington to Phily, in that era, GG1's pulling passenger trains regularly exceeded 100 mph.

OK, not evey working detail, but here is a simple discription - air brakes work like this - train has air line from compressor on loco.

Pressure from loco goes thru train to control valve on each car.

First, at zero pressure, control valve directs air to service and emergency air tanks.

Than at higher pressure the control valve vents the brake cylinder to the atmosphere, releasing any pressure that may be appling the brakes.

When pressure is high enough brakes release, train goes.

When engineer needs to slow or stop the train, he releases some (not all) the air pressure in the train line.

The control valve senses the lower pressure on the train line and sends a proportional amount of high pressure air (from the air tanks on the car) to "apply" brakes. More drop in presure, more braking, less drop in pressure, less braking.

When he has slowed the train enough (lets say he is not stopping), he sets his control to build up the line pressure again, the control valve senses the higher presure, recharges any air used from the air tanks, and vents the cylinder to atmosphere to release the brakes.

So run aways can happen in several ways:

One, no air pressure at all in any components, no manual brake set

or

The angle cocks (valves in the air line at each end of car) are closed, trapping air in system and keeping brakes released. These are used during switching moves as ebtnut discribed and should have been reopened and the brakes tested, but mistakes sometimes happen.

Just to show you how much of a train geek I am, I'm 50 now, but my 7th grade science project was "The Westinghouse Air Brake".


Sheldon

[ebtnut]

Also don't forget that back then there was almost no radio communication among trains or crews, so there really was no way to warn the on-board crew of the problem. 

[Atlantic Central]

ebtnut,

Good point, also, as I recall, it was a tower operator who noted the trains excessive speed and called ahead to the station.

Sheldon