Hope you don't mind a few suggestions. First, will he have access to the area behind the tunnels? If not, how will he reach/fix equipment failures or derailments that happen in the tunnel?
Second, why not set the yard up between the mainlines on one peninsula or the other, instead of outside the mainlines?
Third, since you have included no return loops (which you could easily do), why not make the yard double-ended with double crossovers just outside each end of the yard. That way, trains traveling either direction through the "curve" would be able to enter and/or exit the yard as needed.
Just some thoughts,
Chuck
