Dave,
Both of those ideas have merit. No the grades aren't too steep. The real Blackwater grade was 3.4% I believe, and I tested all my engines pulling about 6 cars up 6% I believe it was with no trouble. It's back there on page 3 or 4 or 5 or somewhere. 
(William and Rich may be on to something there) 
Ah, who cares; I'm having fun!
Back to the plans. The passing siding with the 'extension' for lack of a better word, looks like something one may see on a tight mountain railroad. The real Blackwater had a turnout partway down at Lime Rock, but not a passing siding. I printed them both off. Call me a relic, call me what you will; I can 'see' things better on paper than the computer screen. 
Here is what the yard at Thomas looked like once upon a time. We were there in August, and it is just a grassy area with the bike trail running through it like it was back in '95 or '96 the last time we were there.
Here is the switch at Lime Rock, partway down the grade.
I'm looking for that photograph I sent Dave I scanned from a magazine of a large model railroad of two lines hugging a mountain slope, the lower one being at least two tracks. I must have saved it elsewhere on my cloud drive. Anyway, that would be the view looking through the big window connecting the laundry with the train room. That vantage point is at the bottom of the drawings. Anyway, when I find it, I'll post it, because it is pretty cool.
