Saudi prince, Mohammand bin Salman, announced a future city spread in 170km with no cars and no street. But any place to meet daily needs like schools, medicine and office will not take more than 5 minutes. Further, they wanted to achieve these things in sustainable way, how feasible is this idea?
This is simply a fancily designed chain of cities based on the about 40 years old idea of the "compact city". The idea is to reduce urban sprawl, reduce traffic and improve living conditions.
Each link of the chain in itself will be not self-sufficient, but provide all necessary (daily) needs to its inhabitants, including doctors and if not a hospital, then at least competent first aid. No need to drive 20 km for shopping, no need to commute an hour to work and back, your children may walk to their school. Specialised services/places can be reached via public traffic connecting the cities along "the line". Delivery of goods, emergency response etc. all happen via the tunnels connecting the cities.
Still, the marketing says "no streets - no cars" - which is hard to believe nowadays and triggers some sentiment like Tim showed. While this may be the ultimate goal, I think there still will be areas for the lone car to roll around (ambulance, police, milk delivery guy, whatever...) but they wont be comparable to our current road system. Simply an open space without privately owned cars, only a few cars/trucks on official business going about.
So yes, the idea in itself is feasible, yet futuristic, once you look past marketing bling-bling and sentiment.
When it comes to sustainability, it strongly depends on how you build this city, what ressources you use and how you acquired them. Concrete is a climate killer, unless you manage to produce it using renewable energies. Steel is very similar. You can build small villages from local ressources, but a whole city, let alone a chain of cities - that's hard to imagine. This (german) study on the emission of GHG due to subway-construction estimates that one 1 km of subway tunnel "costs" about 100,000 tons of CO2-equivalents. Now you'll have probably two tunnels, both running 170 km under the cities, that's 340 million tons of CO2-equivalents only for construction of transportation infrastructure. Without more detailled numbers on the project it's hard to do estimations - but I think we can assume, that the construction wont really be sustainable, while living in these cities might as well be.
A "city" implies people. Lots of people. Those people need to eat. Food generally is purchased at (super)markets and grocery stores. It usually is delivered by trucks. No roads means no trucks means no markets means no food means no people means no city. I see a teeny, tiny problem with the plan, don't you?
Of course, one can transport and distribute food "other" ways, but all of them require non-trivial infrastructure and thus need to be decided in advance and constructed as (or before) the city-proper is constructed (probably below it, in all likelihood).
It's easy to say "no roads" but much, much harder to then "distribute food". No member of a modern society is going to walk two hours with a clay pot or woven basket on their head to collect the daily groceries. And even though 2022 is just around the corner, I'm not sure we're quite ready for pipelines carrying Soylent Green just yet.
Update: The neom.com website show roads and trucks on a sub-level. So the streets are still there, and the trucks are still there. They've just put them underground. Nothing 'revolutionary' at all. Dozens of cities (Taipei, London, Chicago, etc.) have such streets. So, in a nutshell, because Neom still has streets, food is actually deliverable in pretty-much the usual way, so Neom is feasible. A city with no streets at all (i.e. something which Neom isn't, and which doesn't exist anywhere on Earth) is still not feasible... and won't be until a new way of delivering food to masses of people is invented.
As stated, Pie in the Sky. Pipe Dreams.
- Vehicle use can be severely restricted -- certain hours.
- Almost all shops will require periodic delivery access for supplies. E.g. A bakery needs flour, sugar. A grocer needs food. A Walmart needs all sorts of things.
- Heavy industry is banished to the edge of the city.
- Zoning laws permit a mix of residence and retail.
- Much of the access to residential areas can be on 'grassed breeze block' drives. These are 4" x 12" x 12" blocks that have holes in them. The holes are filled with soil, and sown with grass. I've seen these used in parks for creating vehicle access where it's on the order of a few vehicles per month. People moving in. Heavy deliveries. Also, police, fire and utility vehicles.
- Such a city would have 2-4 block walks to access to transit lines. You still end up with a road system, but it's 1/4 to 1/16 as dense.
Things working against this:
- It's a lot harder to implement in cold climates. Much of this depends on being able to easily walk/bike/skateboard to transit/school/shops.
- Current zoning patterns with large distances between residential and commercial areas.