So here are some thoughts on the Columbia River I-5 Bridge and its route through Portland. If we’re going to spend billions, let’s get something out of them that will be useful.
Create an elevated platform above for the bullet train. The main thing holding back this is the already overcrowded private freight lines. Using the right of way that we already have is the only way to get a fast system that we can afford.
Keep the width of existing highways and bridges, this will be more than enough for autonomous vehicles, the reason highways are so wide is that humans are easily distracted and not very good at driving.
Make sure all uses of bridges and highways are measured, so use them, you pay for them.
Increase the connectivity of streets and neighborhoods above ground with large overpasses with parks and housing.
The future is neither bright nor dark, that’s what we do with it.