I have all my track layed 2 mains with a crossover a fairly good sized yard. Main curves are 18 inch radius yard is 22 and 18. Not running cars over 70’ most deisels are 4 axle with one sd 24 
I do nor see any yard. small or good sized[:^)]
One more crossover on your main lines would be a good addition Branch thing coming off the odd switch back does not make a lot of sense. Sorry.
A few comments, and sorry if they are a little blunt.
What is the scale? I am assuming HO.
What is the layout size? If i am guessing correctly, it looks like 10 or 11’ x 7’. If so the middle will be nearly impossible to reach for scenery.
Also if you have a room to fit a layout this size (16’ x 11’) it would be a wiser use of space to go with an around the wall plan rather than a island type.
Also the one switch causes issues. You cannot go from the outer to inner track in both directions, you really need to have a full interlocking.
I also second the comment about the switchback and yard, the switchback makes it difficult to get from the main to that back track, the runaround is small, also I will second the lack of yard, I don’t see this good side yard you are speaking of.
What are you looking to do with this layout, run trains in circles? operate?
I would look at a few different plans that have some of the bugs worked out. Depending on what you want to do, take look at the MR beer line plan.
Keep thinking about plans and what you want, and remember, trains are fun!
Chris
I moved the crossover to the long side the runaround i am connecting the yard i added 2 more switches thanks for the input.
Modifications to layout 
I presume the hole in the center is to acesss the scenery around it. Are you ok with crawling under the layout?
Also you have a number of sidings What industries do you plan to service. Its just an opinion but I prefer to service 2 or 3 industries and not try to be a jack of all trades.
The hole is for access to scenery, yes i am ok crawling under to access scenery have to for wires anyway. The short spur going off to the right is for parking my sw 1500. One industry is going to be a micro brewery and feed mill. One a scrap yard and the other one i dont know yet. In my area there are several industries along the river very close together. ADM, Caterpillar, Scrapyard, Komatsu, in my area there is a Short Line the Tazwell And Peoria that does nothing but switch the industries as does the TP&W.
Still need another crossover between the outside mains or trains have to back through in one direction.
Ok The only other comment I have rightnow is you are going to want safety fences around the edge as you do not want an expensive loco to become air born if it derails.
Crossover is planned soon as i get the switches the edge is about 5 inches the track thing is not to scale layout is 7 X 11 and track plan is 6 X 10