DoubleDAZ posted:
Kevin,
I agree with Carl for the most part. I tried to show what a layout space would look like when I posted this image. As that time I had no idea what obstructions needed to be considered. Heck, I couldn't even determine the exact size of the room based on the PDF image.
Anyway, I like to make my workspace in RR-Track at least 12" larger on all sides. For example, your room appears to be something around 27x20, so I would have made the workspace at least 29x22. In that space, I'd then draw the room like you did, but add all the dimensions like Carl mentioned. In your example, I can't tell if the room dimensions are defined by the workspace or the black lines.
Once you have the room outline done and labeled, then draw the space that's available for the layout itself. In my photo, that's the gray polygon. Here's where you need to decide where your main viewing/control area is going to be and how much space you need around the layout for access. While I agree with Carl that 24" is narrow for a walk-around, it may be enough space for access if you're only going to walk around to deal with a derailment, etc. If you want enough space for visitors to be comfortable, then 36" would probably be more appropriate, at least in some areas. You could have 36" along the top and 24" along the sides/bottom, completely up to you.
Now, when it comes to the mechanical room, you need to consider more than just being able to open the door. You need to consider how much space you need to remove things when they need to be replaced. I was going to position my layout to where I could open the door just enough for me to get in, but I forgot that we have a 3'x5' box in the closet that we need to be able to get through the door. The door is on an angle, so it needed to swing more than 90° and the layout needed to be far enough away so we could get the box through.
After the space for the layout is defined, then it's time to start adding track. Like you, my first addition would be the TT. However, once you really define the layout space, it might be better off to the side vs right in front. In your current design, the TT may be visually appealing, but there are no trains running the perimeter of the layout, so visitors are going to be left looking at a TT doing little while all the train action is on the sides and in the bottom right corner.
That said, I like the idea of a bridge crossing over other tracks, but you can room a semi-hidden line around the back corner coming out from the corner and have another line at elevation for the bridge to cross over the lower track. That way your mains could run around the perimeter and your TT could be more in the middle further toward the corner. And, the interesting part of TT operation is the TT itself, so if the min viewing area is near the room entrance, then the TT should be turned 180° so viewers can watch trains come and go from the storage tracks, not just stare at the backs of stationary engines. I'd also consider moving the hidden yard to the front so that you could have trains enter tunnels on the left and right sides that would lead down to the yard. If you allow 36" in the front and 24" along the sides/bottom, 36" would be plenty to allow you to deal with the yard and 24" to deal with problems around the rest of the layout..
And finally, you mentioned maybe closing the door to the mechanical room and opening the wall. I assume you mean the wall along the entryway. If you do that, just make sure you can get larger items out. With the door the way it is now, large can come straight out and then be moved through the entryway. If you move the door, they might have to be turned and the entryway might not be wide enough.
Good luck and please post the RR-Track file along with any photo so we can continue to help. 
