Install using the Blender Assets Browser feature

• Move the downloaded .blend file to your assets folder.
• Reload either Blender or your Asset Browser library.
• If installed correctly, the asset will now be avaiable in the Assets Browser menu.

Alternatively, you can append the Procedural Bridge object from the downloaded file.

Parameters

Curve Resolution: controls the number of "vertices" the curve will have. This do not changes the number of polygons of the final mesh, just controls the shape of the curve.

Piers Interval: the number of piers that will be jumped. If set to 0 all the girder modules will have a pier below it. Increase this to reduce the amount of piers.

Collision Surface: a collection of objects that the piers will have contact. The higher is the number of vertices in this objects, the slower will be to perform calculations, so try to optimize these colliders as much as possible.

Max Height: the Max Height the bridge has. Increase if some pier is not touching the ground.

Pier Offset: controls how far the pier will be from the contact surface. Increase to make like the pier is buried in the ground.

Guardrail Offset: the offset of the guardrail along the girder extremities.

Align Curve: whether to align or not the curve. Disable if you want to preserve the tilt of the curve.

Others: the objects that will be instanced along the curve.

Optional: adapting your own models

Note: I will not enter in the details of modeling modular assets, I will only cover the specific steps to work with this tool.

1. You must have three models for the girder, three models for the piers and three models for the guardrail (the last is optional):

2. These models will be connected in the setup, so you have to take care of the UV mapping and the geometry with that in mind, their connections should be seamless:

3. For the guardrails, the origin must be in the left bottom of the object

4. For the girders, it is the same (mine have a bit of offset to make it sunk in the piers).

5. For the piers it is the most simple, the origin should be at the top center of the mesh.

6. Make sure the geometry do not have lost vertices/edges (like in the image below).