'Large' is a relative term. What's large to some is not so large to others. You might try my Central Valley route which is an enhancement of my Matlin Yard which you might also try if you just want the yard and service buildings.
Mike
A great loco servicing facility with a fabulous detailed interior was done by pigeon on kuid 60697:28002, it's suitable for all countries that operate diesel locomotives....
From the Home page scroll down the picture options until you get to the Trainz sections. Go there and from that front page (I think... can't remember for sure!) select Downloads, it's near the bottom of that page. Each route has a description next to it so you can't go wrong.
Alternatively search my username angelah on the DS and get it from there.