I Agree with Will, this is a nice plan with the general overview i see.
Its hard to tell just exactly what tracks you have in the yard for example but it appears you have simple ellegance here.
Good mainline run,Good off layout staging opportunity(giving you that interchange option
)
Here are a couple of thoughts to consider from an operations standpoint:
1- Division point Yard (you have staging but you need a place to bring the interchange to)
A division point yard will give you a place to handle your locals and your off layout freight.Use your staging area as (the rest of the world) use the division point yard as your Main (on stage) area for directing your world.It appears as if you could add a division point yard in the layout area on the same wall as your staging.Engine service facilities are nice to have but less important than an area to make up and break up those incoming trains.Southern Pacific covers a huge area.If you are Proto-Lancing(free lance based on a prototype) you could for example pick a division that was formerly another road that SP sucked up to give you some basis in reality and a general guideline.This will help give plausability to your road.
If you are going to stay prototype,Picking an SP division will really help to set the stage as you can find out who SP interchanged with, where,what kind of traffic etc.
This also gives the opportunity to add operators(up to 3 easily for a division point yard)
Yard boss,eastbound switching and west bound .
Look over the SP,check out thier differant divisions(and the subdivisions within)If they didnt have mining for example,dont worry about it,thats what Proto -lancing is about.Its a guideline that you can change to suit your interests.That guideline however will really help to develop a truly plausible road.
2- Design Elements-Double check each area to be certain all your Elements are in place(sidings,runarounds,ease of switching(facing vs trailing points)Length of passing tracks(remember, this will define the maximum length of your longest train as a general rule),Number of passing tracks(this gives you the maximum number of trains you can have on the main as a general rule)
3-You mentioned you wanted 2 roads. Consider the 2nd road as perhaps a branch. take that mining area for example.Perhaps a small local road running 1st or 2nd generation diesels a bit rough looking perhaps but affordable for a small road with a regional flavor.(up here i think of North Shore Mining RR as as example) It is a shortline that hauled ore from LTV mining to Silver Bays Reserve mining plant.It also could interchange with the DM&IR for ore to be shipped through a differant Port.
You can do a fair Job with 2 class 1 railroads but in doing so you will lose alot of scenery space,increase your expense dramatically and have a hard time fitting in a 2nd division point yard meaning operations of that 2nd class 1 would suffer.If you want to run engines from another class 1 consider them as Pool power or leased units.Do a good job with 1 class 1 road and 1 regional road(whose yard requirements would be minimal.
This is all my opinion of course .I hope you find something in my ramblings useful and worthwhile to you
I'm jelous,you really have opportunity to do a fabulous operations oriented layout with this kind of room.One that will be fun to operate alone or with 8 -12 friends.
I hope you will have some help building this.Keep in mind, N scale is half the size of HO but doesnt take 1/2 the time.If you have built an HO layout in the past consider this,it will take as long to build this as it would to build an HO layout in a 40 x 32 room ( thats an entire basement in a modest ranch home)
Having help would be very nice.
If you dont, i would build a small layout just to have something to run trains on when you get the urge because this monster is going to take awhile,a very long while.A lifetime for me LOL
