What ones are you using already.
YR ones look good. I've used those often. They are the spline type.
Ben Dorsey made some that are fixed objects at various angles.
There are also lots of UK ones that will work and are at various angles, are splines and fixed scenery types.
What I would like to see are spline overpass deck girder bridges used to cross boulevards as the current ones in Trainz are bit too deep.
Here's what we need:
http://binged.it/1JMch45
http://binged.it/1S62nJI
Notice how much higher these are on the bottom, making them thinner than the ones we have now.
John