What keeps excess height cars from tipping over?

3rdrail wrote: where a train has partially derailed at speed and cars to a locomotive's rear are out of control and are racing towards the rear of such locomotive - would an engineer have the capability to continue to maintain speed to "outrun" the runaway units, or would the train automatically go into emergency stopping beyond the engineers control but setting up the locomotive for a rear end collision ?

I think that's exactly what happened in the video -- the train broke apart, went into emergency, and the head end came to a stop... and then was rear-ended by some of the cars. Looks like it happened on a bridge too, and I think that tank car ended up going off the bridge. I didn't notice that until after I had replayed it a few times.

You're right - it's at a bridge. I wonder if an engineer can over-ride emergency and keep on truckin' in a case like this ?

All that he would be able to do is bale off the locomotive brakes. The locomotive(s) drop power during an emergency application.

Wind can be a strong factor. I was once working as a switchman on a hump job. The wind was blowing empty bulkhead flats toward the hump. We had to push them back and put on handbrakes.
CP had some double stack cars tip over on the St. Lawrence River bridge. Luckily they went toward the other track, and not into the water.I think that the real question was about over dimension loads. I was on a kigh-wide extra once. The load was very top heavy. The clearance papers said to try to avoid stopping on curves, and try to go around them at +15 mph. Harmonic rock can be bad on jointed rail. The cars used for dimensional moves have so many axles that they seem to be less prone. Still the game is to keep it over at 25, or drop to 10.

I'm no expert on this, but I also had the feeling that the engine had gone into emergency so therefore the consist slammed into the rear. We have to remember too that this derailment actually happened on a long bridge. I think the train probably would have survived intact if it didn't cross the bridge where the air turbulance is much higher. The winds going under the bridge increase in speed due to the compression of the air in the space. Remember the Bernoulli effect. This is why it's unsafe to park under bridges during tornados. The increase in air pressure will actually suck the hapless person trying to survive the storm above. So anyway, getting back to topic, the strong winds underneath plus the storm wind across the train created even more turbulance than would have happened if the train remained on solid ground.

I've actually seen a tornado spin down about 100 yards from me, and felt my ears pop from the pressure change. It's quite a sight to behold, and very humbling.

John

Here's a quote from the video description from the national weather service about the tornado hitting the train:

"THE TORNADO THEN MOVED ACROSS THE CHICAGO AND NORTHWESTERN RAILROAD WHERE IT BLEW 12 RAILROAD FREIGHT CARS OFF THE TRACK. THE TRAIN WAS MOVING AT THE TIME THE TORNADO HIT IT...SO AS THE MAIN ENGINE STOPPED...THE REMAINING CARS ON THE TRACK CONTINUED ALONG IT AND SLAMMED INTO THE FRONT PART OF THE TRAIN. THIS CAUSED A FEW MORE CARS TO DERAIL...INCLUDING ONE CONTAINING HAZARDOUS MATERIALS THAT CAUSED THE EVACUATION OF THE TOWN OF LAWRENCE. THE DAMAGE IN LAWRENCE WAS RATED AS EF2 WITH WINDS UP TO 110 MPH."

Apparently, from reading comments far down on the video's page (it was a while ago, couldn't bother to find them again right now) the tank car survived the wreck intact, much to the surprise of those inspecting the wreckage given the amount of punishment it endured. I don't recall what it contained, but it must have been something pretty bad if they had to evacuate the town as a precaution. There was also a comment to the effect that the camera which filmed this should not have even been turned on so it was pure luck that this was caught on tape.

Vakharn wrote:Here's a quote from the video description from the national weather service about the tornado hitting the train:

"THE TORNADO THEN MOVED ACROSS THE CHICAGO AND NORTHWESTERN RAILROAD WHERE IT BLEW 12 RAILROAD FREIGHT CARS OFF THE TRACK. THE TRAIN WAS MOVING AT THE TIME THE TORNADO HIT IT...SO AS THE MAIN ENGINE STOPPED...THE REMAINING CARS ON THE TRACK CONTINUED ALONG IT AND SLAMMED INTO THE FRONT PART OF THE TRAIN. THIS CAUSED A FEW MORE CARS TO DERAIL...INCLUDING ONE CONTAINING HAZARDOUS MATERIALS THAT CAUSED THE EVACUATION OF THE TOWN OF LAWRENCE. THE DAMAGE IN LAWRENCE WAS RATED AS EF2 WITH WINDS UP TO 110 MPH."

Apparently, from reading comments far down on the video's page (it was a while ago, couldn't bother to find them again right now) the tank car survived the wreck intact, much to the surprise of those inspecting the wreckage given the amount of punishment it endured. I don't recall what it contained, but it must have been something pretty bad if they had to evacuate the town as a precaution. There was also a comment to the effect that the camera which filmed this should not have even been turned on so it was pure luck that this was caught on tape.

Here's an explanation of the EF rating, or Enhanced Fujita scale used by NOAA

http://www.spc.noaa.gov/efscale/

This was considered a strong tornado. The EF scale is much more accurate in its depiction of the storm, but it's still subject to variants. The rating can't be applied to storm predictions, and sadly only happens after the damage is done. There could be a very dangerous and powerful tornado in the middle of nowhere, but because it caused no physical damage to buildings, or killed anyone, it would receive no rating. If on the otherhand the storm hit a town, then it would receive the EF rating. This is an area where meteorologists are trying to better predict what the storm will do rather than its after effects.

John