[sqeaky]

We have been struggling to use public transport as a country for at least 5 decades. It works in some areas and doesn't work in others. Seeing some of the failures I don't ever see public transit becoming the only (or at least majority of) transit which is what is really required for the kind of sustainability you are talking about.

Wouldn't lots of Electric Vehicles be just about as sustainable as that? And it wouldn't require changing everything about how transit works in all the places public transit doesn't work.

I live in Omaha, so let me use that as an example. Omaha has about 5x the surface area of Manhattan but only about 1m people (Manhattan has about 5m I think). Getting from anywhere to anywhere takes about 20 minutes (most take more like 10), because we have a huge amount interstate style freeways in town. Rush hour adds maybe 5 minutes to that for my current commute for an upper limit for any trip of 25m.

It is a huge waste of gas that we all use our cars, but there simply isn't the population density to make buses work at scale. There aren't enough hubs of activity that would cause a subway to make sense. Even with public transit for the city we still have to deal with all the farmers near the city so we would still need parking accommodations. In order to get anything like the level of convenience cars provide there would need to be a huge amount of them, with 15 minute car rides a bus cannot compete on convenience.

But electric vehicles combined with all the wind farms we have would make it sustainable and not require changing the way a million people live their lives for no benefit. And it looks like EVs are coming in the next decade or so. Waiting just looks practical, our alternative is to rip up our streets move our buildings closer together and hope that a public transport system will make it worth while.

Public Transit is hard to sell in Nebraska the state that invented arbor day, because it is simply impractical. Try selling public transit in Texas where they actively love oil and actively hate the environment (I would too if I had to giant spiders, scorpions and solifuges that are native to Texas).

[martinald]

The problem is that eventually those freeways will get clogged at rush hour unless you continually expand them, which is crazy expensive if you need to rebuild dozens of bridges etc, and suffers from the laws of diminishing returns (adding a 5th lane to a 4 lane high way does not result in a 25% capacity gain).

I'd be surprised in the long run if even Omaha isn't susceptible to this, and electric vehicles don't really do much to help this (perhaps autonomous driving may allow a small %age increase but I am highly sceptical past that).

Houston and Dallas both have fast growing light rail systems, and there is the Texas Central railway project to link the cities with high speed rail so I don't think they're a perfect example - they also have a massive wind power boom going on right now.

[Xorlev]

> (perhaps autonomous driving may allow a small %age increase but I am highly sceptical past that).

I'm imagining in the future that some roads will be reserved for automated use only except in emergencies. At that point, you greatly increase the trust in individual agents and planning can be communicated ("I plan to move 3 lanes to the right in 1.5 miles, FYI"). Average speed increases, "turbulence" reduces, which improves throughput and speed consistency though doesn't help with exit bottlenecks.

That said, you're right. The law of diminishing returns continues to apply even if it kicks the can down the road a bit (i.e. adding a 5th lane results in a 10% capacity gain without SDVs, 21% gain with SDVs -- numbers are completely made up).

[sqeaky]

> The problem is that eventually those freeways will get clogged at rush hour unless you continually expand them

Only if density increases. It remains constant because Omaha (and many midwest cities) just gets bigger.