I always thought the "Unit Train" concept required the train to stay
together throughout one or more cycles. On CPR they started with the
Fording coal trains in 1969 or 1970. No switching was involved at either
end; the train set returned empty to the mine unchanged for another load.
Other roads may have had earlier examples.
"Solid Trains" of one car type and commodity go way back in history, the
silk trains being just one example. But they did not return to the loading
point in the identical formation. Most solid trains were broken up at the
destination. Returning empty cars were typically given low priority or
reloaded individually with goods that had to go somewhat in the return
direction.
I don't have certain knowledge of British practice, but suspect only the
modern "mgr trains" meet this more limited definition of a unit trains. I
believe mgr is short for merry-go-round".
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Yes, MGR's (Merry Go Round) trains, AFAIK, introduced the concept of "unit
trains".
A single design of freight car hauling one product from manufacturer to
customer in a continuous cycle the train never being broken apart except to
remove and replace cars requiring maintenance.
And yes, a unit train goes from "A" to "B" to "A" to "B" in a cycle, which
silk trains didn't do.
Cheers.
Roger T.
Home of the late Great Eastern Railway
http://greateasternrailway.com
More photos of the late GER at: -
http://s94.photobucket.com/albums/l99/rogertra/Great_Eastern/
