Idler Car Wrote:
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> The replies are all very interesting, but do not
> answer J Mann's question: why not just hook the
> loco on the other end of the string.
>
> The replies all say, in different wording, just
> that such is the procedure - but no one explains
> WHY that is the procedure.

It's related to (1) traffic flows and (2) geography.

Traffic flows: West Colton's primary function is to reclassify manifest traffic. After inbound traffic is "humped" it's pulled down into the Departure Yard. The majority of the outbound traffic goes east on the Sunset route, northeast on the ex-LA&SL, or north on the Palmdale-Colton Cut Off. All of these routes are located east of the yard. Westward-heading traffic consists mostly of haulers and locals, plus the memnants of Coast Line traffic. Trains that do not originate, terminate, pick up or set out at West Colton can bypass the yard on the main.

Geography: The yard was designed to fit the topography, which is downhill from west to east, hence it's a gravity yard and not a traditional hump yard. The layout is described in my original post on this thread.

Because of the two above reasons, the yard was not designed to allow westbound trains to easily depart westward from the Departure Yard. It can be done, but it tends to disrupt the fluidity of the yard. On the other hand, it's possible to depart westward from the Arrival Yard, and that's historically been done such as when picking up blocks of west cars that have been set out in the Arrival Yard.

So, most westbound trains depart eastward from the Departure Yard and head around the balloon. That's not to say there haven't been problems, but that's the way it is.