So the episode didn’t really touch on population density and transit interconnect. They indirectly touched on the subject of reach-ability of users to transit.
But I thought the best was the CA HSR PM who was really super positive on the building of a 165 mile segment to reach 3M people for $30-50B.
Building rail is expensive in the US compared to other countries. With the longer distances in the West and lower pop density, the costs become extremely prohibitive. DC-PHL-NYC-BOS corridor, Houston-Dallas, and South FL are all great candidates for a US version of HSR.
SF-LA – not so much. The problem is once you get to LA, your mass transit options are limited. For a family of 4 not going to DT SF/LA, it’s cheaper and easier to drive.
The only way this is happening is if it’s underground or in the air using a new form of transportation (i.e hyperloop)
As for making CA cities more dense, that’s something that will take decades to occur. At least to make cities as dense as other cities in Europe or Asia that can sustain mass transit. Yeah, there will be some places that will reach it sooner rather than later, but getting projects approved takes a long time due to the process of getting projects approved (And that’s with a city council that ignores local homeowners). (I’m on one of the SD Community Planning Councils) How many decades will it take to get a SR-56 to I-5 interchange, lol?