Hello,
I would like to know what the proper height of bridges should be in HO scale layouts. Currently I use Faller bridge piers (7.5 cm tall) with the Faller track beds. These are not high enough to run my electric locos with their pantographs up.
I am soon going to be building foam ramps and would like to know what the ideal height should be so that in the future, I can run caternary wires under them.
Thanks.

Märklin suggests the following minimum bridge heights:

For M or C track without catenary: 74.5 mm
For M or C track with catenary: 104.5 mm
For K track without catenary: 68.5 mm
For K track with catenary: 98.5 mm

Hope this helps.

If you are prepared to do some modification to your catenary than the 75 mm is enough for electric locos. You usually don't need to put a full mast under a bridge. I first made my layout without catenary and added some after. In some places it required some creative thinking (tunnels) but it always worked. In my very shallow tunnels I soldered a copper overhead wire to guide the pantographs

Seeing the pantographs flex in and out is an added bonus ;-)

Bert

This really helps. But I have 75mm bridge piers + faller track beds on C track and the pantagrophs hit the bottom of the track bed. I guess 104.5 or 120.5 should help. Thanks.