Realistic 3D modeling of a tunnel, based on images video and AutoCAD design

Our company specializes in visualizing transportation infrastructure assets defects.
We use 3d model to visualize the customer asset, and add images on top of that model. The models are displayed over the browser using three.js, so it has to be efficient for rendering over the browser while keeping as close to the real thing as much as possible.

At the current project, we have a tunnel that's used for different utility cables and pipes. We need to create a 3d model that's 2KM long.
We have detailed CAD design for all the tunnel, but images and videos for only 500M, so we want the entire 2K model, but only 500M will be textured.