Up until the 1960s, the boxcar was the dominant type of freight car. Over the next two decades, there was an explosion of new designs: covered hoppers, rotary and bathtub hoppers, centerbeam for lumber, autoracks, articulated deep well for containers, pneumatic hoppers, etc. But since then, the industry has been content to just make tank cars safer and to make all cars a little bigger to grow their weight from the 263,000 lb standard to the 286,000 lb standard.
Since I'm one of the people who did the research that moved the industry to 286,000 lb. cars, I can explain. We started a study of the costs and benefits of overloading 100 ton coal hoppers on BN in 1987. As it happened, given the size (4000 cubic feet) of the cars, and the size of the heap determined by coal's angle of repose, the cars could physically hold enough coal to bring total gross weight to 286,000 lbs. So that's what it became.
Another part of the study looked at new car designs for both 286K and 315K cars. The 315K cars were an economic "no go", since they cost more per cubic foot of capacity than the 286K cars (larger wheels and axles, mostly) and had a poorer net-to-tare ratio.
A standard coal hopper weights about 60,000 lbs. With a 286K weight limit, it can carry 226,000 lbs. of coal, or 113 tons. Aluminum coal gondolas in service today weigh as little as 42,000 lbs., meaning they can carry 244,000 lbs., or 122 tons of coal. A comparable 315K aluminum hopper weighs about 55,000 lbs., so can carry 260.000 lbs. of coal or 130 tons. But the 122-ton car weighs less relative to its capacity, and costs less too. That's why you don't see the industry moving to 315K cars. [TO20050114 (forgot to save the specific trainorders link), msg rresor]Exceptions to "no new designs in decades" are trash cars and a couple of autorack designs and some niche markets.
Trash cars have two platforms that share an articulated truck in the middle. This is the only one I have seen while doing some railfanning for five years on the BNSF Racetrack in Downers Grove, IL.
Greenbrier introduced an articulated autorack car that they trademarked Auto-Max in 1999. In addition to being articulated, it has adjustable decks to switch between bi-level and tri-level.
But this design evidently didn't catch on because I sometimes see an autorack unit train with none of them. And now I seldom see more than a few of them in a unit train. But I did catch a train that started with one Auto-Max car and then had a cut of seven of them.
Actually, just because I don't remember seeing them, doesn't mean I haven't seen them. I came across some more examples of Auto-Max cars while looking for deep-well cars in some 2014 photos of the Lemont Bridge.
In 2013, Greenbrier introduced the Multi-Max design. I assume the reason the Auto-Max did not take off is that they had to buy the whole car from Greenbrier. The Multi-Max rack supports the tradition of separate owners for the flatcar vs. the rack on top of the flatcar.
A common example of an articulated car design is deep well flat cars for double-stack container traffic. I remember reading about 7-pack and 10-pack cars. But the industry seems to have settled down with 5-pack, 3-pack and singletons.
Greenbrier is proposing that all railcar designs become articulated. Specifically, they are working on reducing the length of a body without sacrificing its volume. In fact, they have increased the volume of some designs. A shorter body allows more bodies to be hauled without increasing the length train of the train. But shorter bodies would increase the slack in the train. Reducing slack, and further reductions of weight and length, is why they want to articulate their new designs. [FreightWaves] I look forward to these new designs because it should not only reduce transportation costs and greenhouse gas emissions, it should make train watching more interesting.
One issue is that shortening the bodies means more weight on the bridges. When a track is rated for 286,000 lbs., I wonder what length is assumed.
Update: It's not articulated, but it is shorter at 50' 6". According to some Facebook comments I saw, other manufactures are advertising 5400 cubic feet cars whereas this car holds 5185 cubic feet. "Design features of the new railcar, include longer hatches for improved filling efficiency; rounded stiffeners for stronger sides; Tsunami Gate for customized unloading speed—as quickly as 30 seconds; automated unloading for improved worker safety; “align to close” tabs for clear indication that the Tsunami Gate is closed, locked and sealed for transport; and aerodynamic performance for up to 53% reduction in drag." [RailwayAge] Now that I think about it, I suckered for the hype about articulated cars. Bulk cargo freight cars are designed to utilize the 286,000 lb. capacity of trucks. That is why grain covered hopper cars are longer than sand or cement covered hoppers. Since articulation would double the weight on the middle truck, I don't see how it can be done.
|Screenshot from Greenbrier's press release|
Update of Update: Articulated hoppers have come and gone already.
|Chris Cruz posted|
Still looking fresh, these examples of the articulated Super Hoppers were on display at the Topeka Railroad Days, circa 1991. My photo.
Dennis Garrett When they were new, I got called for a test train with one of these, from Kansas City to Newton. We left around midnight, and the Road Foreman rode with us. Every single time I turned on the light, he was asleep, just the way I wanted him.
Stuart Thomson Great photo.I was always intriqued by this concept. But it required the right combo of movements to make it happen.Santa Fe also had that Fuel Folier bulk container that straddled a spine car. Very ballsy but hard to get the right combo of two way shippers. Santa Fe took chances and sometimes you don't win.
Stuart Thomson Not sure if this was a Budd division Transit America design or if it was a Trinity original. Trinity had trouble with aluminum covered hoppers. This concept required unit train service with quick unload which those hopper gates were not great at. Some of the new designs might work better.