Hmkay, just a few suggestions how a bridgesegment could work. I'd like if it would be build with the hammer. Because I think it wouldn't be really navigatable through the landscape if you had to push it around.
So when you select to build the thing with a hammer the preview would stick to the mouse like all other buildings, ecpect it doesn't adjust itself to the ground. It can "float" freely around. But it only turns green when one or two sides are in solid material, so it has a fixation that makes some sense. When you place it, it would be cool if you could adjust the angle of the bridge. So on the first click it wouldn't place the final construction site, but lock the one end that is in solid material. Then depending on how you move the mouse you could change the angle of the bridge and make it for example go a little upwards. If both sides are in solid material it locks the opposite end of the bridge where your mouse cursor is and changes height of the end where the mouse cursor is. On the second click it places the construction site and makes it extend a little to left and right, so you can place your materials in it. Adding new segments works with the snap-feature, like the elevator. Snapped-in ends would always stay locked, even if the other side is in solid material, too.

Another option is to place several bridges at one time. You place again the first segment with the mouse into solid material. But then it doesn't only adjust the angle, but also the length to the position of the cursor. And it only turns green, when really both sides are in solid material. So you could quickly place a bridge, that goes all the way from the bottom left to the upper right corner of the screen.

Then it's a question how much material a bridge will consume? One wood per segment? 3 wood and one metal? Maybe more? How easy should it be for players to acces certain points in the landscape?

Do you have other suggestions how the placing and behavior of a bridge could work?