In that same issue of Trains (April 2009) the article "Nice Ride!" by Tom Murray on grain cars (pp. 42 - 44) indicates that current grain covered hopper cars are about 5,200 cu. ft. capy., with an allowable gross weight for unrestricted interchange of 286,000 lbs.
Since 1 bushel = 1.25 cu. ft. (per a Ohio State University web page), the 5,200 cu. ft. hopper can hold about 4,160 bushels. So a 110-car train can carry around 457,600 bushels = 36.6 % of Milton's 1.25 million bushel capacity.
As a check, a University of Missouri web page (and other sources) says that wheat weighs about 60 lbs. per bushel (exact figure depends on moisture content and some other characteristics). So a 5,200 cu. ft. hopper car carrying 4,160 bushels would have a payload of 249,600 lbs., leaving 36,400 lbs. for the weight of the car without exceeding the allowable gross car weight. That's a little light - Rodney's figure above of 60,000 lbs is more correct - so the these cars carrying wheat will "weigh out" before they "cube out" (or "bushel out" ? ).
Revising these figures accordingly:
286,000 lbs. gross - 60,000 lbs. for empty car = 226,000 lbs. max. payload per car
226,000 lbs. payload per car / 60 lbs. per bushel = about 3,770 bushels per car.
110 cars per train x 3,770 bushels per car = 414,700 bushels per train
414,700 bushels per train / 1.25 million bushels capacity of Milton = 33.2 % = just about 1/3 of its capacity.
So it appears that the Milton elevator can altogether store about 3 trainloads of grain, depending on its density. But as I previously noted above, they may not have been sure that they actually had enough wheat for this train, if they already had some bins filled with the soybeans and canola.
And it just occurred to me that here's probably the real technical reason: Once a bin has even a little bit of those other grains - canola or soybeans - in or left over in them - then those bins are not available for use in storing wheat ! We don't know how many bins Milton has, so we don't know what fractions or percentages of its capacity are effectively "off-limits" by those other bins being already partially filled or committed or reserved for those other grains. But even if those other bins are only partially filled with the other grain, its entire capacity is then not available for the wheat. Specifically, if two or more grains were put in the same bin - even as separate layers - I don't know how a grain elevator could skim or separate the one grain from the other grain with the kind of equipment that is used to empty them - hoppers or compressed air lifts, etc., typically. So, the desired grain would run a good risk of having other grains mixed in with it, which would ruin its market value. Im structures that big, I suspect that the volume of intermixing that could occur would be pretty large.
Interesting discussion and analysis. Anybody else out there have more insight on this ?
- Paul North.
A bushel of corn is 56lbs, a loaded covered hopper car weighs 243,000 the empty weight is 60,000 which means that their is 183,000lbs of corn in bushels that is 3,267.8571 a 110 car grain train will have 359,464.28 bushels of corn that is well under what milton can hold.
Rodney
Good catch on that nuance ! 1 million bushels at the referenced 60 lbs. each = 60,000,000 lbs. = 30,000 short tons, = 2 to 3 trainloads, "depending".
The article says Milton has capacity of 1.15 million bushels, then: "Milton ships mostly spring wheat, followed by canola and soybeans." About 40 shuttles of wheat per year, but only 2 to 3 of soybeans - nothing said about volume of canola; corn isn't even mentioned for Milton.
I'd speculate that a good portion of Milton's capacity is taken up by canola and soybeans waiting to accumulate to a full shuttle train's worth. If there's much more than half a train of either one, that elevator could then be down to less than 1 train's worth of wheat capacity. Let's see what others say, too.
On page 67 of April Trains it seems to be saying the elevator at Milton can't store enough to load a 110?-car train-- but it says capacity at Milton is more than a million bushels. The train can't carry a million bushels-- right? Not even half a million? So am I misreading this somehow?
(Wikipedia says a bushel now usually means 54-60 pounds of corn/wheat/soybeans, rather than the traditional definition in terms of volume-- but that doesn't affect the matter significantly, does it?)
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