> if you have autonomous vehicles, you don't need a lot of expensive infrastructure inside the tunnels to get from A to B. Infrastructure like rails, signaling

> if you have autonomous vehicles, you don't need a lot of expensive infrastructure inside the tunnels to get from A to B. Infrastructure like rails, signaling equipment, power lines for the trains, etc. 2 lanes of 3 rails that are grade leveled should be relatively less expensive than paved, with rebar grade leveled; especially over time, with the increased wear that liquid has.