ECOTONE

I was one NWK-WAS yesterday on the 5:14pm Acela. I noticed pretty strong, sustained northerly winds and began to wonder how that would affect my trip south to DC. Does the train get better "mileage"? Does that metric even exist for trains these days?


Figured that someone on here would know the answer to this bizarre question of mine.



This confirms the fact that my mind wanders A LOT while on the platform at NWK!

cheers everyone!

Ispolkom

I'd imagine that it would be hard to find any effect on train efficiency from even sustained winds, since the train's relationship to wind direction changes, as does the effect of nearby topography and buildings on wind direction.

That's not say that wind can't affect trains: http://www.youtube.com/watch?v=LYubpuIe3cw

Ispolkom

Duplicate post.

gatelouse

Strong Fall winds move trees
Branches, wires fall, debris...
Now arriving: late.

Mudhen

A strong cross or headwind might affect acceleration. Also a strong wind "might" affect signals; I know a good thunderstorm will.

jackal

Objects respond to air resistance (i.e. wind blowing) as a function of their frontal surface area in proportion to their weight. Think of how a piece of paper gets blown around in the wind, while an equivalent-sized piece of sheet metal is much more resistant to being moved, and a heavy brick is almost immovable except in tornado-force winds.

A flat piece of cardboard has an extremely high surface-area-to-weight ratio (assuming it is held up perpendicular to the wind). An aircraft has a much lower frontal surface area, but it is still heavily affected by wind because it is made to be extremely light (using lightweight metals and even now carbon fiber).

A train, on the other hand, has a very small frontal surface area (10x15 feet or so) and is far, far heavier than an equivalent aircraft. A Boeing 767-400ER carries, in a two-class configuration, 304 passengers. Without fuel, the aircraft weighs 229,000 pounds. (Fully loaded with full fuel and a full load of cargo and passengers, it can weigh another 221,000 pounds, but aircraft rarely go out with a full load of fuel unless they are flying the longest of routes.)

On the other hand, an Acela trainset can also carry 304 passengers and weighs, when empty, 1.24 million pounds. That's over five times heavier than the equivalent airliner, which also has a larger cross-section and many extremities sticking out (wings, engine pods, etc.), which all affect the resistance of the machine to move through the air. Even fully loaded, a 767 is far more affected by wind than a train.

The other major factor affecting headwind/tailwind performance stems from the propulsion method aircraft use: pushing air. For every increment of headwind, an equal increment of thrust is reduced. A 100mph headwind means that the thrust force of the aircraft is reduced by 100mph, and the aircraft will travel 100mph slower.

Not so with a train. The train may have a little more wind to push itself through, but the force to do so is not directly equal to the thrust. Think of it as the "airplane on a treadmill" thought experiment in reverse: just as a treadmill cannot materially affect the speed of an aircraft sitting on top of it, wind cannot materially affect the speed of a ground-propelled object pushing through it.

That said, and as illustrated above, winds do affect trains in the form of blown-down trees lying across the tracks, tornados picking up cars and spinning them around, knocking out power lines and thus killing electric rail service, and the like.

Also, "miles per hour" is far too small of a measuring unit to be effective with large transportation vehicles. Aircraft and diesel railroad engines use gallons-per-hour as a standard measure of engine efficiency. I don't have direct knowledge of electric locomotives, but I would suspect the standard kilowatt-hour (or a higher variant of it--megawatt hour? ) is used. To calculate passenger or freight efficiency, the figures of either BTUs or passenger-miles-per-gallon or ton-miles-per-gallon are generally used, which show the amount of energy expended per passenger (or per ton of freight) for every mile traveled.

the_traveler

In plain English, jackal says "NO"!

Headwind or tailwind dies not affect Amtrak. However, lateral wind speeds may stop a train - for safety reasons! I have been on a few trains where the crew and dispatchers have stopped the train if the winds were too high (We were held until the winds had either died down or it was determined that there was no danger.) While the train may not blow over, trees and other obstacles may blow onto the tracks!

nerd

No, the thrust remains the same, and the airspeed remains the same. The groundspeed is, of course reduced by 100mph, but not by the means you describe.

bmorechris

On the California Zephyr route out of Denver up the Front Range of the Rockies, there is a windbreak at the Big 10 curve. More info and pictures can be found here. At this location there are often high winds that sweep down out of the mountains and have in the past blown high profile cars off the tracks (no passenger cars have been blown off, but high-profile autoracks have. Amtrak's Superliners would be susceptible to this because they are tall and also relatively light for a railcar.) The railroad decided to create a windbreak by laying a track and placing about 2 dozen loaded hoppers on the inside of the curve. The siding was disconnected from the main, the hoppers were welded to the rails, and then painted an earth tone to blend in with the surroundings. Map view here. Additional pictures here here.

fairviewroad

Very cool links!

^

ibrandsguest

The catenary in the Northeast Corridor has been blown down, as per NJ Transit announcements, by high winds. I suspect that the reason was really age of the wires, though.

Re: the Acela's weight- isn't the Acela way way heavier than other high-speed trains- and presumably heavier than conventional trains, due to FRA safety mandates?

jackal

Yes to the first one. Not sure about the second.