What Do You Think ?

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What Do You Think ?

Postby 3rdrail » Sat Nov 17, 2012 9:17 pm

Hi All ! I've finally gotten the official railroad investigation on a historic wreck that I'm interested in. I won't tell you which wreck it is, not that it's a big secret, but I don't want you to be prejusticed with old lore as this wreck is over 100 years old and it's supposed "cause" has been pretty much established over the years. I've come accross a part in the investigation that I would be curious for anyone that knows anything about train wrecks to comment on. This is a wreck which was located at a small bridge carrying commuter rail trains over a street approximately 36 feet below. It is commonly believed that the bridge gave way, causing the engine's cars to fall to the street below. There were 9 cars and an engine/tender. The engine and it's tender made it accross the bridge. The first 3 cars broke away from the tender and remained up on the embankment and had TELESCOPED INTO ONE ANOTHER. The remaining 6 cars plummeted down to the street on the collapsed bridge.

What I can't understand is how the first 3 cars got telescoped considering that they made it accross the bridge. Although derailed, they generally followed the right of way...but impacted each other. From what I understand of the early days of telescoping at railway accidents, there usually was tremendous force, such as head-on collisions where this would happen requiring considerable energy. I can't imagine where this considerable energy would have come from up on the embankment level.

Here's a photo from the wreck scene. All of these cars have made it beyond the collapsed bridge. I would expect to see moderate damage at the area of union between the 3rd and 4th car (far left of photo), where the train seperated falling into the street - not the telescoped devastation that we see here running along the plane of the embankment. From the look of the cars, it almost looks like they got pulled down off the embankment onto the street below and then up again onto the embankment, but I realize that that's highly unlikely. Visible are the first three cars and the roof of the fourth car. Any ideas ?
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Re: What Do You Think ?

Postby EDM5970 » Thu Nov 22, 2012 12:33 pm

Just speculation, but when the air went into emergency, the engine and tender, being heavier than the cars and having more adhesion on the rail, stopped quicker and got rear-ended by the three or four coaches, with their combined inertia keeping them moving. That is, if the pictured equipment had air brakes.

I do know, from my study of various air brake systems several years ago, that 24-RL (much MUCH newer than the photo) had a feature (Rotair, lead freight) that would delay an emergency independant application on the power to let it 'run away' from a break-in-two. This suggests that the scenario described above is possible.

Interesting question; hopefully someone with a better physics and train dynamics backgqrond will weigh in.
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Re: What Do You Think ?

Postby MBTA3247 » Fri Nov 23, 2012 6:19 pm

Looking at the picture, the first car doesn't appear to have been telescoped, or hit at all. I'd guess it derailed because of the drawbar forces from the derailing cars behind it.

With the telescoping of the second and third cars, I'd hypothesize that the bridge gave way underneath the second car. The first truck of that car made it over ok, but the second one got caught on the abutment, slowing the car enough for the third car to slam into it. Inertia carried the second and third cars onto the embankment (it kinda looks like the underbody of the third car got torn off), while the remaining cars fell on top of the ruined bridge. No idea how the roof of the 4th car got torn off.
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Re: What Do You Think ?

Postby 3rdrail » Fri Nov 23, 2012 9:55 pm

You probably have guessed that this is the infamous Bussey Bridge Wreck which took place in Roslindale in 1887. The official cause was reported as the breaking of hangers at the north end of the Hewins truss casing failure of the bridge, but I'm wondering about this tremendous forward energy that we see post bridge. Here is a schematic drawn that's in the official report showing where the cars were found "at rest". Three cars were left post bridge up on the embankment, six cars were left on or near South Street below.
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Re: What Do You Think ?

Postby 3rdrail » Sat Nov 24, 2012 5:18 pm

Great replies guys. You've given me a lot to consider. It might shed some light on the scene that a conductor in the 2nd car reported being knock backwards off his feet onto the floor when he first was given a physical indication of a collision where he became unconscious. When he awoke, everyone on board (only about three people) had scampered out the windows to safety. This conductor then left on his own and testified that he noticed that the 2nd and 3rd car were sitting on the roadbed without trucks. He did not testify where the trucks were as he stated he did not see them, so presumably they went through the open bridge. The crew testified to an operation at the time of the incident of about 12 MPH. The train was also about 5-7 minutes late coming out of Roslindale Sq. Station. Seven of the nine cars had Westinghouse Automatic Air Brakes but the train could not be in automatic as two of the cars had straight Westinghouse Air. The locomotive/tender remained intact and on it's rails and proceeded to race to Forest Hills to announce the wreck so that help would respond.

Now, something is not right here. For numerous cars to be telescoped and lose their trucks, there has to be tremendous energy. For any car in the train to telescope another in the same linear direction ups the amount of force necessary. I cannot recall another rail accident where cars in the same train telescoped each other. How could a train travelling 12 MPH do all this ? I have no doubt that this train was doing substantially more than 12 MPH, but even so...

Here's the ground scene...
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Re: What Do You Think ?

Postby MEC407 » Sat Nov 24, 2012 5:38 pm

Fascinating!
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Re: What Do You Think ?

Postby MBTA3247 » Sat Nov 24, 2012 6:47 pm

3rdrail wrote:I cannot recall another rail accident where cars in the same train telescoped each other.

Telescoping usually did occur with adjacent cars in the same train, with the occasional exception of rear-end collisions, where the locomotive or lead car of the following train could telescope the rear car of the first train. If you dig through train magazine archives or books on railroad accidents you'll find plenty of pictures of cars from the same train telescoped into one another.
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Re: What Do You Think ?

Postby 3rdrail » Sat Nov 24, 2012 10:35 pm

My experiece with wrecks has largely been with electric railway equipment, which have occasionally been trained and involved in a severe collision. It is not that common there. Usually, the coupler, drawbar, draft spring, etc. is sufficient to absorb low to moderate energy crashes. After the utilization of anti-climbers, telescoping was reduced, although the same force was exerted. The most severe cases of telescoping tend to be high energy crashes whereby two cars are travelling in opposite directions (or one runs into a staionairy car). I just don't see how a train travelling at even twice the reported speed as this one could have the energy to produce so much devastation as seen in this wreck. Play it over in your mind as if you were sitting down watching it as it unfolded. Think of it in terms of watching a train travelling 24 MPH (2x speed reported) foul a bridge. Does it wind up as we see this one pictured, partricularly with the cars still up on the embankment ? It doesn't in my mind. All that I can think of is that this engineer was hauling ass and doing @ 40 MPH on straight air brakes in a restricted zone due to being late. I explain the cars on the embankment as that the bridge giving way may not have been the initiating event causing this crash, but perhaps a brake rod or other large piece fouling the gauge prior to and including the bridge, doing damage to key elements to the bridge causing it to fail. It doesn't do my theory much good that the bridge's designer had no prior bridge building experience, had another bridge drop that he built causing a fatal wreck, and that the company building the bridge really didn't exist except on the contract signed. On the other hand, the builder was never charged with anything, and went on to be quite the hob nobber with the MIT crowd.(???)
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Re: What Do You Think ?

Postby MarkB » Mon Dec 31, 2012 6:31 pm

If the bridge started failing after the locomotive cleared it and dropped down a limited way under the following cars, then as the next car hit the no longer level bridge-embankment meeting point, there would be a sudden shock pulling the car and locomotive apart. Once the car rode up over the embankment, it would suddenly be free to move forward. Any time you're dragging something that gets stuck and it suddenly comes free, it's going to come flying at you.
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