It depends on what you want to optimize. Usually cities build new roads hoping to eliminate traffic jams, but city after city has found that there is essentially infinite demand for free car lanes in urban areas. There are only two things that can fix traffic congestion:

1. You can demolish large chunks of the city so that fewer people have a reason to visit, and spread development paper-thin over a wide area so that it stays beneath the incredibly low density threshold that causes car congestion. This is the approach taken by most US cities after WW2, however it has only worked in cities that have gone into economic decline because the places with meaningful growth consistently fill in more densely than cars can accommodate even with half the old downtown reduced to parking lots and strict zoning laws etc.

2. You can charge for the roads. Congestion pricing deters people who don’t really need to drive at a particular place and time from doing so, and thus allows the roads to flow freely even in urban centers. Surprisingly, it doesn’t take a huge toll to eliminate rush hour, as (1) the tipping point for traffic congestion is roughly the last 10% of cars that can fit on the road, and (2) it turns out that there’s a lot of low-value driving on the margin which simply stops when there’s a price attached to it.

The smart option is #2.

Option 3: Plan your city so that average trip lengths are too short to make cars the best choice.

Option 4: Build excellent public transport so that cars are not the best choice.

Option #3 is, in my opinion, a pipe dream. I say this because in years of studying this topic (first professionally, now avocationally), I have yet to see a newly built urban area of any meaningful size where life happened primarily within walk-shed rather than a car-shed. The genie is out of the bottle, people want cars, and the only way to have an urban environment where they aren’t helpful is to have an urban environment where they aren’t allowed. this speaks to the utility that cars offer. What has worked is limiting cars, and this is especially effective in pre-car cities such as the urban centers of Europe.

Option 4 is also very difficult to achieve. Even Tokyo, with its legendary transit coverage, also has a ton of car traffic. What is much easier is to recognize that if everyone plows into their car for every trip we’ll all be stuck in gridlock, then put congestion charges in place so that everyone who can feasibly get their trip accomplished without driving is incentivized to do so, and the trips that really require a car are able to pay the fee and then have a nice trip quality.

I don't think cars can be completely eliminated from cities, but I'm reasonably sure that we can remove at least 2/3rds of the car traffic by a combination of better urban planning, and better public transport. I don't think you have to restrict yourself to walkable distances. Ten minutes on a bike allows you to go several kilometers. I bet I can reach a quarter of my city in less than 15 minutes. If we make cycling safe and comfortable, that alone can eliminate a lot of traffic. Add in good public transport for trips that are longer than a few kilometers, and another big chunk of car traffic becomes unnecessary.

I lived a few months in Tokyo, without a car of course, and got by very well with a shitty mamachari and the subway. I wonder what the modal split in Tokyo is like, compared to other cities. I bet most person kilometers are met by trains and subways.

>then put congestion charges in place

That's less about removing congestion and more about clearing the roads of poor people to make room for everyone else unless you pay road toll as a % of income and assets.

And since traffic congestion is essentially constant, you can also reduce the available car lanes and replace them with other denser modes of transport (public transport, protected bike lanes, …). It won't make congestion worse, as the increased inconvenience… will simply make less users drive.

It becomes more important to reserve "transfer nodes" (especially at the edges) where drivers can drop their car and hop on other transport modes though. That is something which is often lacking.

For option #2, do metered highway entrances provide a similar effect? On the one hand, the goal is to prevent that last 10% of cars from being able to enter the highway during peak hours. But on the other hand, unlike tolls, it isn't known until you reach a highway entrance whether they'll be present, so they wouldn't impact trip planning as much. So I could see it going either way.

I think that metered entrances don't necessarily reduce the number of cars on the freeway, for exactly the reason you mentioned. Instead, it is designed to break up 'platoons' of cars from trying to merge in at the same time which cause ripple braking effects and traffic jams. The net result of meters is squeezing more cars at the same speed and maximizing flow rate of traffic.

So you wait a little bit at the meter but your (and everyone else's) overall travel time is actually faster. I recommend this YouTube video (and the whole channel) for great explanations of the traffic dynamics.

https://www.youtube.com/watch?v=30uzZRSVxXQ

Metered entrances help a bit (I've seen the difference in traffic when they went from being installed to operaring in santa clara county), but you would have to run them very aggressively (long cycles) to eliminate congestion, and people would not be happy to wait for that long.

When the line from the meters spills onto the adjancement roadway, some people will take alternate routes, but mostly people want to get onto the freeway because it's the best route, even if it's congested.

> That's like saying that building houses doesn't solve the housing crisis because they are immediately bought.

I'm not sure Jevon's paradox applies to houses, whereas it absolutely applies to car traffic.

See also https://en.wikipedia.org/wiki/Braess's_paradox

> adding one or more roads to a road network can slow down overall traffic flow through it.

Like it or not, that increased car traffic delivers more utility.

You can't have a car free metropolis. That's a contradiction.

> Like it or not, that increased car traffic delivers more utility.

It rarely delivers enough utility to even compensate for it costs.

> You can't have a car free metropolis. That's a contradiction.

It's absolutely not, your assertion is outright nonsensical.

Car-centricity is by far the worst way to build a metropolis.

“Car free” is one of several ways to not be “car-centric”, but not the only way. I believe it’s possible to make a car-free metropolis, but I don’t know if any (modern) metropolis demonstrates this.

Sure but I’m not the one which set up this straw man dichotomy and saw no reason to care for or acknowledge it.

The utility vehicles, buses, delivery of goods to stores etc are percentage of overall vehicles on the road and require little infrastructure compared to using cars as main individual mode of transportation.

Paris is certainly trying. The idea that you need a car to move around a city is probably cultural.

Paris is hardly the only city doing that either, and far from the first.

While a fair bit smaller, Amsterdam is probably a better example here (and it helps that they got started in the 90s).

And as points of difference (aside from size), Amsterdam has a much smaller metro network, but a larger tram network (Paris completely shut down its tram system in the late 30s and has been rebuilding it since the 90s, whereas Amsterdam's tram network was never completely shut down, and while a number of Amsterdam's tram lines were switched over to buses in the 40s and early 50s, trams got repopularized very quickly, as soon as the late 50s).

You can't have a car-free metropolis, but you sure can have a metropolis where cars are used by much, much fewer people than is typical today.

Oh look, a 5 minute old account created just to be argumentative.

>That's like saying that building houses doesn't solve the housing crisis because they are immediately bought.

Makes sense. London is blessed with apparently empty high rise apartment blocks. 'Investment' flats, bought by foreign owners, who haven't seen their places and have no interest in them. It's just a safe place to store their wealth and they don't care if they screw up everyone who's actually trying to buy a home. Tax empty homes, should help things a lot.

Now, my idea to solve congestion is a bit different. For useless, bloated big SUV's, place restrictions and taxes on exterior options like alloys and paints. Incentivise smaller cars. That should help congestion a bit. And is it just me or are even supposed minis absurdly bloated and elongated these days?

How would taxing a particular paint effect congestion?

It's an accumulation of small things. Forcing blander paint colours and less 'bling' in general on over-sized cars, will disencourage unnecessary purchases. Instead of looking to go flashy with a huge Mercedes G-wagen, people will look at smaller cars. Smaller cars may partially help with congestion. At the minimum, they pollute less.

If you want people to pollute less, charge more for generating the pollution.