The thing about long bridges is that what you really need to build them is lots of one-off parts and for the design process to need rapid prototyping of parts.

The other thing about bridges is they only need to be built once and not maintained, and you can basically make a bridge for whatever budget you happen to get. That's why a gofundme works so well as a funding model. You can even have a stretch goal to support weird vehicles like trucks, cars or rail, in addition to the base goal of just AI-powered electric scooters.