I recommend to email prof. Vuchic and ask for a piece of advice. Self-driving public transit systems (a.k.a. MRT or Metro) for American cities may be an interesting topic.

https://vuchic.seas.upenn.edu/overviews/

Dear Sergio

I and other colleagues undertake work in this area - feel free to contact me at [email protected] to discuss.

Cheers

Sally

Check if someone is interested in support you to do smart shrinking studies for the US rust belt cities.

I think ETH has the best programs in these areas.