LG Gleason,
you can damage bridges by melee or with artillery bombardment. You just move a unit adjacent and melee with the bridge as if it is an enemy unit. The same way, you can order your guns to fire at a bridge and damage it. When the bridge value is reduce to zero, it is destroyed.
If I'm right, there is no way to repair them in the course of a battle. But I made a test with Peninsula Campaign and the bridges are usually repaired at the start of a new battle in the campaign. I presume that it is the same with Campaign Gettysburg.
Note: small bridges on hexsides of a stream or creek can't be destroyed. Only bridges who occupy full hex can be damaged like the ones you could find on the Potomac.
Capt. Harold Lajoie 3/2/I/AoM, CSA.
