[Skybird]

Bridges, like breachings of minefields, are funnel-type obstacles. They work pretty reliably, if following some rules.

If needed, lay smoke to cover the event from enemy eyes.

Go to column formation.

Use routes, if possible. Preferred method would be to set at least two waypoints even in planning phase, and link them through a "march order"-route. Make sure that the waypoints are positioned so that vehicles can line up BEFORE the stone walls of the bridge to both sides of the road begin. All vehicle lineup should have been completed BEFORE the first vehicles moves onto the bridge. Use moderate speeds.
You can hold the shift-key when setting waypoints on a road. By that an automatic makes sure that the waypoint is really attached to the right traffic line of the road, even if you do not hit it exactly.

And very important: TIMING. Make sure that not more than one platoon at a time is busy with crossing the bridge, and that it has cleared the bridge area before the next platoon enters the close vicinity of it. Same is true for moving on roads: traffic jams can make life a mess up if you don't have a reasonable spacing between platoons - keep the fourth vehicle of the first platoon at least as far away from the first vehicle in the following platoon like you have set a unit spacing (narrow, medium, wide). The lead vehicle eventually slows down, giving another platoon time to shortehn the distance between the two - so compensate for that. Vehicles that are on roads will try to stick on roads, if movement direction is not off course by more than 30°. If there is a vehicle of another platoon on a vehicles position in it's formation", the driving AI starts to "fight" and negotiate the position, the collision with the other unit, and the will to stay on the road - not good.

So, coordination and timing are the keywords, use column formation and march-orders, and keep a space between platoons. Finish all lineup in column before the unit reaches the bridge. Best is to pre-plan it via conditioned routes in planning phase, and set triggers or conditions when what unit should do the crossing.

Same thing with the breaching of minefields, but here even more coordination is needed, since one unit brings forward the Miclic, another one ploughes (?) through the breach, and a third one set the flag markers - and then the normal units follow.

There is, however, a problem with the AI, it gets stuck even in ridiculously small bodies of water, and even amphibious tanks. Right now, think of ALL water as inescapable traps. Unfortunately, this unwanted feature is confirmed not to be addressed in the next addon or patch. So, keep a good distance between units, and water. When a tank set up a battle position near a thin rivulet of water, and gets engaged, it eventually moves back and fourth to remain hull-down. This could get him stuck - so keep an eye on this.