> Drawing a (admittedly inaccurate) parallel with shared spaces (which are harder to navigate by sensory deprived humans than standard intersections), I'd say roundabouts (which preserve crossings) would be a more sensible short-term approach overall -- especially considering the remaining human drivers.

I actually find roundabouts easier to navigate than large crossroads, I think this is partly because they actually are objectively easier and safer to navigate (one stream of traffic) and partly (but mostly) because they are dominant in the UK.

But for the same reason (familiarity) I expect many in the US would find roundabouts hard to navigate (and maybe unsafe as a result?), it's more about what you are used to and what you had to learn as part of your driving test.

Are roundabouts part of driving tests in the US?

It wasn't part of my driving test in Virginia, at least when I took it. I'm guessing if your state has a low number of roundabouts [0] then it's pretty unlikely you'll be tested on it. I'd be interested to hear if Marylanders (#1 in roundabouts:intersections) have it on their test.

Personally, I freak out when I see a roundabout coming up, and slow down dramatically. Or, I completely avoid them.

[0] https://www.citylab.com/transportation/2016/03/america-traff...

It's possible that even when slowing down the roundabout still ends up being more efficient, since you don't have as much "stop/go" action going on

This is generally how it works in the UK, except for newbies who tend to always stop completely rather than try to time the merge where possible... I've heard that this is actually taught in advanced driving in the UK (to maintain flow when possible, time merges etc). Frankly there are some roundabouts in cities at rush hour which are frightening for new drivers and you just can't join unless you have good timing and can get up to speed quickly (or get a lucky smooth merge).

This is exactly the question asked by myth busters.

You can see the segment here[0]

They measured throughput for both 4-way stops and roundabouts, with both people who hadn’t used them before and people who had.

Unsurprisingly (for me at least) roundabouts were significantly better, even for people unfamiliar with them.

0: https://m.wimp.com/mythbusters-four-way-stop-vs-roundabout/

Roundabouts are not part of the driving test in DC. Indeed, roundabouts are so scary to Americans that most of the ones in DC have traffic lights. We also have roundabouts with roads cutting across them: https://ddot.dc.gov/sites/default/files/dc/sites/ddot/ward%2....

hah, that is completely insane! the design completely looses all the benefits of it being a roundabout. Even those crazy triple mini roundabouts make more sense than that one.

n=1, but roundabouts we’re not a part of my driving test in Texas. That said, driving tests are done at the state level, not nationally.

re shared spaces, from the wikipedia:

> Hans Monderman and others have suggested that, by creating a greater sense of uncertainty and making it unclear who has priority, drivers will reduce their speed, in turn reducing the dominance of vehicles, reducing road casualty rates, and improving safety for other road users.

clearly, Hans Monderman has never driven in Mumbai, India.

I think that shared spaces make sense in small towns, university campuses, and other contexts where traffic flow is low due to the inherent context (and, above all, where pedestrians can support each other).

But for modest to high volume traffic, roundabouts are better (although if the traffic flow is constant, you usually have to place the crossings a bit further away from the center of the roundabout, which makes it a little harder on elderly pedestrians to go fully "across" since they have to walk the extra distance).

They actually introduced a shared space at Amsterdam Central Station about 1-2 years ago that I cross daily. The shared space is right next to the incredibly busy ferries and perpendicular to what used to be a bicycle lane. It's now one big square shared by bicycles, pedestrians and scooters.

It does work incredibly well and there are rarely any accidents. The downside however is that it's quite a struggle to cross. It makes me dread to leave the ferry and enter the warzone once again every morning. I understand that it is designed to make me uncomfortable, but it is taken to such an extend that I don't even really want to walk there.

> one big square shared by bicycles, pedestrians and scooters

You mean, no cars?

For high traffic, a roundabout would have to be truly huge. It isn't viable unless land is practically free. You need something more like this:

https://en.wikipedia.org/wiki/High_Five_Interchange

That crosses 16 lanes with 14 lanes. (3,5,5,3 with 3,4,4,3)

>clearly, Hans Monderman has never driven in Mumbai, India.

I'm reminded of my time in Berkeley. Now, in spite of what Fox News might tell you, Berkeley is one of the most ridiculously upper class places possible. But, it's right next to Oakland, a place that... isn't.

In Berkeley? If you even look like you were about to step out into the road in the middle of the street, people would stop for you. Over in El Cerrito or Oakland? you could be in the crosswalk, and nobody even slows down.

> clearly, Hans Monderman has never driven in Mumbai, India.

Or Naples, Italy.

In Barcelona they have "Superblocks"

https://www.theguardian.com/cities/2016/may/17/superblocks-r...

I grew up in Canberra, known as the roundabout capital of Australia [1] as well as being the actual capital of Australia. It has a population of ~350,000, 406 roundabouts and 276 traffic lights.

In my experience they keep traffic moving really well, as long as the traffic load into each entrance is roughly equal - otherwise it's hard to enter the roundabout from a lesser used entrance.

They take up more space than traffic lights in most situations, however Canberra is a planned suburbia so that wasn't an issue there.

[1]: http://www.abc.net.au/news/specials/curious-canberra/2016-12...

Roundabout throughput drops when traffic load increases. They are useful (and great) for low volume traffic/suburbs.

Many towns add them precisely because it regulates traffic flow near homes.

If you have such a high-traffic road, shouldn't you use interchanges instead anyway?

Even for large roundabouts with traffic lights?

Yes, large roundabouts have horrible throughput vs the space they take up.

I don't think roundabouts would work in the Bay area because it requires that people know how to use turn signals.

So the solution is a full switch to autonomous vehicles and a ban of all manually driven vehicles?

People will learn to use turn signals quickly if they are fined.

I think for now increasing the requirements to get a driver's license Should help.

Works well in Europe. Though I can understand why this wouldn't work in the US.

How has life been with transportation abstracted away into an app? Any unintended consequences?