If anyone needs some good, custom-cut wood for trestles, etc, I highly recommend Northwest Precision Lumber. I’ve gotten all my wood from him. He uses western red cedar and will cut it to your specifications. Besides trestles, he’s supplied the ties for my bridges, scale lumber for headframes, ore bins and other structures, and I just ordered some smaller ties for my mining tram. I’ve found his prices to be reasonable and he gets it out quickly.
Yes,
I use Jim @ NW Precision for all my custom lumber machining.
Those pics of my bridges and ties were made out of material cut by him. The cedar that is.
The redwood came from Bob at Garden Texture.
I plan on delivering a pick-up load of redwood heart wood to him for some redwood custom cutting in the near future.
He’s a one man operation, part time. So don’t you guys flood him with orders. I’ll never get my material! 
His name is James Warren if you want to e-mail him for quotes.
jb