Given the apparent ferocity of that storm and the exposure of trains up high on that bridge, one does wonder if a stop should have been placed on that bridge. Nobody hurt but it could have been far, far worse.
MargaretSPfan Member # 3632
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I, too, wonder why this country's RRs are not using technology that existed long ago that might possibly have kept that train off that bridge then:
(From another forum):
"Milwaukee Road's bridge at Beverly, WA, had a wind-speed sensor that would turn the signals red if the wind speed was excessive."
I have no idea what the MILW considered "excessive", but this technology existed long ago, and really should be used on the Huey P. Long Bridge and other bridges in areas where high winds are common. I know that dispatchers will issue high-wind warnings to engineers and conductors.
It is past time for modern RRs to install and use such high-wind sensors on bridges -- and elsewhere. The MILW was not ahead of its time -- just sensible.
George Harris Member # 2077
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Don't know about Huey P. Long, but wind sensors are used on quite a few bridges. Also, some railroad companies have hired specialized weather service to warn them of tornado / high wind, and other potential problems.
Stacked empty containers are a special case. They are very light and hence easy to blow over. To try to explain it simply: The wind force on a stacked container, or any other thing for that matter, is the same whether it is loaded or empty. However, if it is empty, there is much less weight holding it down.
Think of the weight as if the weight of the car is an arrow aimed down centered between the rails. Think of the load as an arrow aimed sideways halfway up the sides of the two containers. Think of these as each operating pivoting about the downwind side rail. If they sum up rotating sideways, you blow over, if they sum up rotating down, you do not.
Geoff Mayo Member # 153
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I wonder how an Amtrak Superliner stacks up (sorry!) against a pair of empty containers? I suspect that the Superliner is a tad heavier low down with the A/C/heating/pumps equipment, maybe water tanks if they're of any appreciable volume - but then otherwise mostly air. Also not as high as a double stack, I think?
Vincent206 Member # 15447
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Quick research shows that a Superliner (85 feet long) weighs about 148,000 pounds (I presume that's empty). A Greenbrier deep well car (~77 feet long) weighs about 54,000 pounds. Add a couple of empty 53 foot containers (@ about 11,000 pounds) and the total weight of a well car with 2 empty 53' containers would be about 76,000 pounds, or about half the weight of an empty Superliner. That doesn't mean I'd feel safe crossing the Huey P. Long bridge in a Superliner during a heavy storm.
George Harris Member # 2077
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Superliner is 16'-2" tall. Double stacked containers get to about 20'-2" above the rail. The rounding of the top of the superliner compared to the squared off containers reduces the resistance further.
MargaretSPfan Member # 3632
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Thanks, guys, for the fascinating info! I did not know what Superliners weighed. I, too, would not want to be in one during a wind storm.
So glad the RRs are using wind sensors and the services of specialized meteorologists.
I appreciate being corrected, so I can know more, and thus be able to share facts. Thank you!
Geoff Mayo Member # 153
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Thanks George/Vincent.
I recall reading about anemometers on the railroads. Pretty simple devices, presumably not overly expensive either. What I can't remember was whether they had a dedicated signal/indication, or whether they were directly cut into the actual interlocking logic, thus dropping the regular signals.
Here's a photo of the MILW bridge over the Columbia. From having "been there done that", I can report first hand, that the wind can "whup it up" through that canyon.
According to a Wiki article from which the photo is linked, the bridge is not used for anything at this time.
George Harris Member # 2077
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The issue of wind on bridges does get study and treatment. There are such things as wind fences that reduce the effect of wind. BNSF has several installed on high bridges. Yes, there are anemometers also installed in the vicinity of several bridges that have wind issues. How connected to the signal system may not be the same in all cases. Such is the case with slide fences.
Areas subject to typhoon winds also have wind fences in high risk areas.
There are or were some bridges in the Sierra Nevada that had signs prohibiting running VW vans across then. Anyone remember how unstable in any sort of wind these things these light little boxes were?
Iron Mountain Member # 12411
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Last October, 2013, we were returning from the Grand Canyon on the Southwest Chief. We were making pretty good time. The "Chief" got over the Raton Pass and was rolling along somewhere in the flat country of eastern Colorado. I was expecting a fast run through this part of the trip. The train slowed down considerably and remained at a slow pace for a longtime. I asked the conductor why we were going so slowly. He said that they had a slow order because of the cross winds. So, not only on bridges, but also on the wide open prairie wind can be dangerous of high profile cars.
George Harris Member # 2077
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quote:Originally posted by Iron Mountain: . . . eastern Colorado. I was expecting a fast run through this part of the trip. The train slowed down considerably and remained at a slow pace for a longtime. I asked the conductor why we were going so slowly. He said that they had a slow order because of the cross winds. So, not only on bridges, but also on the wide open prairie wind can be dangerous of high profile cars.
This particular part of the country was mentioned in the discussion I read several years ago concerning the benefits to the railroad of having a contracted meterological service to give them gepgraphic specific warnings of events of particular concern to the railroad. Localized flooding was also meentioned in addition to winds, either straight line or tornado.
mpaulshore Member # 3785
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I have to say that seeing this video confirmed what I'd always suspected, namely that not having walls on railroad bridges is an example of unjustified technological bravado and excessive thriftiness that railroad bridge builders of long ago clearly imagined were appropriate, but that in fact never were. This bridge ought to be retrofitted with strong walls, both for wind blockage and to prevent derailed trains from falling to the ground, even if it means that certain parts of the bridge need to be strengthened or even rebuilt to support the additional weight of the walls. I consider that kind of simple, low-tech, low-human-involvement solution to be far more satisfactory than diddling around with weather prediction systems.
Taking a broader view, this accident, like so many other rail accidents, highlights the inherent flimsiness of a technology in which the wheel-axle assemblies are only half the width of the cars, the cars are excessively narrow relative to their height, and the flanges that are supposed to keep the wheels on the tracks are insanely small. It seems to me that if our civilization continues for a few more centuries, eventually the whole rail system will need to be rebuilt with tracks at least ten feet wide, cars no more than around two feet wider than the tracks on each side, and much larger wheel flanges.
By the way, doesn't this thread really belong in one of the non-Amtrak forums? Maybe a moderator should move it there.
George Harris Member # 2077
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Mr Paulshore:
I hardly know how to address your points. I will just say that I have been doing railroad track and civil engineering for most of my 47 years working life, and the way things are in the railroad civil and mechanical engineering world is where they have gotten in what is now over 180 years of railroading.
Wheel flange: No need to change anything there in height or width. Long term studies any many parts of the world have led toward very close to the same answer in all locations, and very much the same whether 10 mph or 200 mph and 10 tons per axle or 35 tons per axle. That is, about 1 inch high in US customary units or 25 mm in SI units. Flange shape is also much the same. There are variations in wheel tread shape, but coning at a slope of about 1 in 20 is the most common. Likewise, except for a few, a rail head crown radius of 8 inches in US units or 200 mm in SI units appears to be the generally accepted best fit.
Walls on bridges? Any cost-benefit study says the money is better spent elsewhere. The wind fences have been used in particularly problem areas. The Huey Long bridge is not one of them. It has now been in use 80 years, and so far as I know no such event has happened before.
The proportion of vehicle width to track gage, or better put, center of rail to center of rail has also been beat upon extensively and the 2 to 1 ratio is also fairly well been proven satisfactory for those systems where overall clearances permit.
Height of center of gravity and overall height of vehicles may be pushing their limits with double stacks. Bi-level passenger cars are used on 3'-6" gage tracks as well as standard gage, although those on the narrower gage are not as high as superliners.
Ratio of height of center of gravity to rail spacing is more significant than overall vehicle width. To widen the track gage to be only 2 feet narrower than vehicle width would be a tremendous waste of resources.
Incindentially, the standard AAR (Association of American Railroads) vehicle width is 10'-8". US standard passenger cars or more on the order of 10'-0" wide. The standard Shinkansen car width is 3380 mm (11-1"), which is not really that wide compared to the standard Japanese coach width used on 3'-6" gage track.
RRRICH Member # 1418
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George -- I have always wondered about flange height myself. The 1-inch standard height of a flange still seems awful short to me to be able to bear the tremendous pressures of a several-ton freight car or even an 85-ft passenger car, especially around bends where the speed limit is often quite high. Don't the flanges ever "erode," and don't tracks sometimes have "rough spots" on them, which could pop off a flange quite easily?
I know it is not a good comparison, but when I was a model railroader, I had trouble keeping my lightweight plastic rail cars on the track, even with their prototype scale height flanges (that's one reason I gave up model railroading).
Geoff Mayo Member # 153
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It looks like there's not much flange but don't forget three things: 1. There'd be an awful lot more derailments if it wasn't sufficient. 2. Using figures above, even an empty container car exerts a downward force of about 3.3 tons per wheel (it's quoted that about a square inch of rail is in contact with the rail at a time) 3. The conical wheel shape George mentioned "steers" the wheelsets to the center of the rails - again, gravity being used to great effect.
George Harris Member # 2077
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In the picture is worth a 1000 words category, note that most of the derailed cars in the Philadelphia derailment are on their sides.
Wheels are checked regularly, and upon reaching a "condemning limit" get to take a trip through a wheel lathe, or if not enough is left, scrapped. Track can be pretty rough and the cars stay on the track. The FRA has a whole list of speed based requirements as to how rough is too rough.
By the way, my "47 years working life" is post-degree. My first year paying into the Social Security system was several years before that.
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