The figure varies from city to city, but the analyses of such matters generally show well over 50 percent of the land area of modern cities is devoted to the automobile. The figure sometimes ranges much higher. (This includes streets and parking.) At the same time, congestion only gets worse. So yeah: let's accommodate another doubling of the population by doubling the area devoted to cars. Right. Brilliant move. Even WWI generals eventually learned that they couldn't overpower trenches and machine guns with massed infantry charges. I wish the commuter and trucking lobbies had as much capacity for insight.
I live in DC. The interstate highway system was designed when Washington's population was 7-800,000 and the automobile suburbs were still a gleam in the developers' eyes. Today the Combined Metropolitan Statistical Area (which is the measure that is relevant for transportation planning, especially for commuters) is nearly 10 million. People in the outer ring, if they commute into the core, can count on 2-3 hour commutes, which is no different from working in NYC and living in Connecticut, or the wilds of New Jersey, or way out on Long Island.
You can't build a sprawling megalopolis with more than ten times the population sharing the same road net and pretend the game hasn't changed. But that's exactly what the car lobby demands. More asphalt is their answer to every problem. And if they get their way, we'll continue to sacrifice livable inner ring neighborhoods with reasonable commutes to build congested commuter sewers for people who insist on living as far away as possible. Your front yard and quiet tree lined street? Sorry, we need another traffic lane. Your neighborhood park? Sorry, we need another access ramp. Your sidewalk? Sorry, we need every inch for traffic, and sidewalks are too expensive anyhow, a luxury that shouldn't be the responsibility of roadbuilders; if you want to cross the street in front of your house, get into your car and drive down to the nearest safe crossing. Your bikeable neighborhood street? Sorry, this must now become a high speed commuter road, and it's too expensive to build a pedestrian/bicycle overpass.
No more. That game is over. Sorry, car commuters. Move closer to your jobs. Or telecommute.
Yes, we should take care of existing infrastructure. But beyond that, we have to look to qualitative rather than quantitative improvements, at least in major metropolitan areas. (West Dogpatch can continue its love affair with the private automobile, at least for a while longer.) Smart roads are potentially a game changer. So will be the shift to fleet transportation and autonomous cars. The biggest change will be a shift to more mixed use neighborhoods with homes, jobs, retail, parks and other amenities integrated into human scale communities build around intermodal transportation options. A walkable/bikeable neighborhood with easily accessible mass transit really is a nice way to live in modern cities.
Lyft and Uber are important steps in this direction; there are now a growing number of cities where increasing numbers of people simply dispense with the private automobile in favor of ride sharing systems. Young people especially are open to this cultural change, since they already think life is an app and everything else is just impedimenta. The importance of this from a planning perspective is that it significantly reduces the amount of parking that is needed. Most cars spend most of their time parked, which is a huge waste of space in dense urban areas, where it is not unusual for a quarter or more of the total land area to be devoted to parking. That's where we can wring more efficiencies out of the existing infrastructure resources.
Put autonomous cars and smart highways together and we will buy a lot of flexibility. But none of it matters in the long run unless we stabilize population.
Your ideas are good ones. The only problem I see with them is some of these “livable” neighborhoods closer to DC are infested with MS-13 and other ferals.