Looking at Track at Tincup

So true to my word I mentioned I wanted to let the track plan evolve around the mainline as it was built.  I realized yesterday the current track plan for Tincup had a problem with it.

The plan, as seen above, was for Tincup to have a siding and interchange line along with a turntable.  For those not deeply steeped in what these are, the mainline is where the train does it primary traveling to and fro.  The siding is a place where cars (boxcars, gondolas, flats, etc.) are left to either be loaded or un-loaded with cargo.  In the case of Tincup the siding will go by, as just one example, a depot where passengers can get on and off the train.

The interchange (the top-most track) is a representative track for leaving cars for another narrow gauge railroad to pickup.  In the real world cars can move between railroads who use the same size track.  This allows a boxcar that starts in Maine to end up in California.  The place where railroads swap cars is called the interchange.  On model railroads we can't model the entire world so these interchanges tracks are shortened down to just one or two sidings that we mentally recognize as representing a place where another railroad would pickup or leave cars.

Now the problem with Tincup is that a train entering from the North (left in the drawings) would be trapped by it's own cars on either the mainline or sidings.

Which, you can guess, is a huge problem if I intend to actually operate my trains instead of just letting them look pretty sitting still.  You see, the business of the railroad is moving things from there to there, so if the engine pulls into town towing 3 boxcars behind it, and it needs to leave those boxcars for a local manufacturer to unload, the train needs to get back on the mainline somehow.

I was looking through back issues of Model Railroader and trying to keep an eye out for how terminus towns of point-to-point layouts were designed and I found this interesting track layout:

The way many railroads solved this problem was through the use of a "run around track" -- that is a siding that was connected at two points to which the train could leave cars then go forward and somehow get around those cars.  The layout I found in Model Railroader took this one step further in that it coupled a run around track with a turntable at the end of the line.

Many people might think of a turntable as primarily something that would be found next to a roundhouse and whose main use is letting engines go into and exit from the roundhouse (this is probably thanks to Thomas the Tank Engine).  However a much more useful purpose is spinning the train around.  If the train enters Tincup from the North pointing South, on the return trip headed North the train needs to be pointing South.  A turntable makes that possible.

However looking at the layout above I realized it comes at the cost of two things:  The sidings get shorter and the interchange is lost.

Both of these are easy bits to solve, which gives us what might be the "final" (ish) track plan for Tincup:

I dropped the turnout at the end of the track before the turntable because it's mostly redundant.  Where possible railroads, especially narrow gauge ones would have preferred the option that was cheaper (ie. less track).  Doing this has the added bonus of the sidings can stay longer.

Since the mainline is now on the top, this also gives us back the interchange.

This track layout works the exact same as the previous one.  Trains entering either via the siding or the mainline run into the turntable which can both spin them around facing the correct direction and let them access a run-around track for the purpose of leaving cars.

Now my only issue is to find a nice-sized turntable that won't break the bank.