I need to have 4 short, relatively modern bridges where the track on the bridge is curved. What is the best way of doing this?
There are no curved bridges. Viaducts can be curved, but are really made up of lots of little short straight sections.
To have curved track on a short bridge, you can just make the bridge a little wider. It can have a ballasted deck, or not. I would recommend against any sort of “through” bridge, where the sides are higher than track level, just for ease of clearances.
If your bridge is long, then do as above, but you will need a pier to allow each section of the bridge to be angled to make the curve.
Andrew
Micro-Engineering has a line of bridge kits and parts in N and HO scale, and you can kitbash and combine them to make what you need, including a curved bridge made of articulated 40’ sections.
—jps
Kato makes Unitrak curved viaducts, I removed the unitrack and used them. I also removed (dremeled) the sides that are above the track for clearance.
I’ve seen 6 cruved bridges.