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Comment by rapnie | Hacker News Reader

In the Netherlands we had a huge phase of replacing regular crossings with roundabouts, which I consider to be an improvement. Now, however this is followed by a re-engineering phase of many of these roundabouts. The 2-lane ones, where a driver needs to pre-select whether they want to go a quarter round (turn right in Netherlands) or select for straight-ahead and 3 quarters round. The lanes on these roundabouts are separated by a rather high ridge to avoid drivers changing their mind and change lanes. This probably done for safety, except that they feel more unsafe now, by introducing "choice stress" upon entry of the roundabout, especially if the road directions aren't very clear. To me it feels like over-engineering.

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If I understand correctly, you mean turbo roundabouts https://www.ms2soft.com/resources/turbo-roundabouts/ ?

If so, IMO they're the best thing that happened to roundabout design ever. You do need to choose a lane before entering but it's similar to how you'd choose a lane on a traditional two-lane roundabout. However, then you don't change lanes while on the roundabout, with ~zero visibility to the other lane while turning in a fairly tight circle.

This may differ across countries but around here you're supposed to: * pick the inner lane unless you're taking the first exit (to the right) * change to the outer lane just before your exit

which is about infinity times more stressful in traffic (you have very little time, it's hard to see the outer lane and the outer lane has right of way). It would work fine if everybody followed the rules but 1. they don't since it's unsafe in a tragedy of the commons sort of way and 2. then you end up with an informal turbo roundabout anyway.

A compromise that's becoming fairly common is a "soft" turbo roundabout where the lanes are divided not by ridges but by solid lines you can't cross only legally, not physically :)

Thank you for the name. Yes, that design. As I just commented below the stress point shifts to entering the roundabout where people crazily yank their car sideways to be on the proper lane. At all cost avoiding the feeling of having made the wrong choice. Kind of road rage psychology. And anecdotal, YMMV. I think here the soft turbo is a great compromise.

Seems like that from your description the turbo roundabout is only a problem for people who do not know it or know where there are going.

We have both types here. And now that I think about it, the turbo trades a bit more stress on first usage or a lot less every time after that. While the standard 2 or 3 lane is always similarly stresfull.

We do have a partially soft design of turbo roundabouts with phisical deviders and designated places where you can change a lane.

Turbo roundabouts also have a significant bonus in throughput, have significantly less points of conflict than a normal two lane at the expense of longer lead-in roads. A single lane is safer but has a drawback in cars per hour.

All the different rules for roundabout are fun. In the UK you’re expected to filter to the outside leave. In Iceland the person on the inside has priority to leave so you can still enter the roundabout but need to watch for someone already on the inside wanting to leave at your first exit. The rules are similar to the Netherlands in that you either go straight or 3rd exit from the inside and should only go first exit on the outside, although it’s totally possible to carefully go all the way on the outside. I still find the Icelandic system mildly bonkers but not due to the choice stress as it’s usually obvious which lane you need.

Yes. One gets used to the system and then it works okay. That ridge dividing lanes may be there for safety reasons.. but one thing I observed is the anxiety to choose wrongly, and the subsequent road rage when wrong decision was made. Both intoducing to my noob eyes new safety hazards. And then I didn't mention cars that deliberately drive over the ridge.

Careful with terminology too, because "inside" and "outside" don't mean the same thing to different drivers, particularly in the UK compared to elsewhere.

Many people hear "inside lane" on a motorway and think it's the "fast lane" near the central divider but that's actually the "outside lane". ( source: https://dictionary.cambridge.org/dictionary/english/outside-... ).

But that terminology has been confused over time and so many people get it the wrong way around that the DVLA has stopped using it in the highway code.

Do you know the origin of the UK use because that always confused me as it’s obviously wrong from the drivers perspective of the road! My wild guess would be that from the drivers seat you look outside to the fast lane and look across the inside of the car to look to the slow lanes.

The normal terminology for the sides of a car are 'nearside' and 'offside', with the nearside being where the kerb is, offside being where other cars would be.

So I would suppose 'inside' and 'outside' were also considered relative to the kerb.

The fast lane is the furthest lane away from where you'd enter the motorway, therefore it's the outside lane (or so the logic goes!)

But... aren't entrances/exits usually on the "outside" of something?

Wow, I'd never thought of it like that. I'd always assumed "outside lane" was the lane closest to the "outside" of the road (ie. the edge) and "inside lane" was the opposite, and was very confused when I found out some people used it the other way around.

> “In the UK you’re expected to filter to the outside leave.”

In practice, large multi-lane roundabouts in the UK usually have lane markings as you enter, with specific lanes for each exit. In general, so long as you were in the correct lane as you entered the roundabout, the lane markings should guide you to the correct exit and you shouldn’t have to do any filtering.

Except the surprisingly common case that lanes are mislabelled... Ie. "I was in the lane marked M4, I followed that lane round perfectly, and suddenly the label in the lane changed to A205! I better change lanes. Oh actually the lane I was just in is now marked M4 again."

The problem seems to be that a lane that goes to two places is sometimes marked inconsistently with each of the two places - meaning you think you are in the wrong lane, when you are not.

And the good ones have lane markings that guide you to the exit as you go around too

Yeah for sure, otherwise it'd be quite scary! Although there are plenty, particularly where there might be more exits where its pretty easy to mispredict where your lane will end up.

I generally dislike these "turbo roundabouts" the first time I encounter them. Always a second of confusion the first time, which is definitely not something I want to feel while driving.

That said, if I enter one I am already familiar with I'm perfectly fine. I guess it depends on who you are optimizing for.

“Choice stress” is a good thing if it encourages drivers to be alert and cautious. The safest road/intersection designs aren’t necessarily the ones that encourage you to relax and feel comfortable.

Ohh, these turbo roundabouts also prevent doing multiple laps while figuring out where you need to go. I can see how that'd be stressful when you're in new locations!

Choice stress is what makes it safe, though. The driver _should_ be a bit stressed. And removing the possibility to change your mind in the roundabout reserves more mental capacity for looking for pedestrians (like me! Hi from Hilversum, which is pretty crappy by Dutch standards but a dream compared to anywhere else I've lived)

A person more stressed has less mental capacity for everything else including pedestrians, why the heck do I have to explain this to adults? Stress leads to mistakes, every single time, in any activity. Whole sports and strategies are based solely on making competitor more stressed to induce mistakes and lose.

And yet they're safer. All data so far seems to show that turbo roundabouts are very safe.

There's a sweet spot. "Eustress"

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

You might find https://news.ycombinator.com/newsguidelines.html an interesting read.

And there's ample research showing that drivers respond to low-stress designs by going faster and not paying as much attention to things on the periphery. https://grist.org/cities/heres-why-narrower-streets-are-safe... or the illustration at https://i.pinimg.com/originals/e2/e0/dd/e2e0dd89a67fe1df1e6d... are useful.

Would you be so kind as to explain to me your thinking to the contrary, ideally with sources?

There was a fad a couple of decades ago for "mini-roundabouts". They woud install these at junctions with a record of accidents. They were dirt-cheap, because they consisted of simply a couple of roundabout signs, and a circular bump about 6" high and a yard or so across, with smooth sides (i.e. no curb, you could easily drive straight over the bump).

The rationale for these things was that they induce uncertainty in the driver, prompting him to slow down, pay more attention, and look more carefully. There are other schemes that were intended to induce uncertainty. The problem with all these schemes is that they depend on unfamiliarity to work; once a particular mini-roundabout is familiar, it no longer induces uncertainty.

On the ring-road around my hometown, there is a series of "hamburger roundabouts". These are large, multilane roundabouts, with traffic-lights as well, and with a lane-pair that runs straight across the central circle, for through traffic. These configurations have never become at all familiar to me; they always induce uncertainty, and I hate them.

Those roundabouts are crap and people just drive over them. They're effectively unmarked 4 way stops, at least in Ireland.

If it's physically possible to drive over something, drivers will. A round concrete blob won't matter.

> And removing the possibility to change your mind in the roundabout reserves more mental capacity for looking for pedestrians

I don't buy it. Ending up forced to take an unexpected exit in a city triggers a lot of things for me and none of those are pedestrians:

- which lane should I be in for the quickest way back?

- what are the rules on the road I'm turning into? (this may be extremely not obvious if you didn't remember the sign for the road you weren't supposed to be on)

- does this road have restrictions that mean I actually can't be on it?

- is this going to send me on a toll road? (the joys of ending up on a single lane bridge which requires coins to cross and there's 5 cars already queued up behind you)

It's less of an issue for country roads, but being in the wrong lane in a place like this: https://maps.app.goo.gl/H8p1n8dcJ9D8epDG6 may mean you're doing a 30min detour to the same intersection and you'd better get it right this time!

Right, and when the junction design forces you to take the route you already decided on all of those decisions are moot. You are forced to decide _before_ you're mid-junction with people going all sorts of different directions. When you take the wrong offramp do you back up on to the freeway?

The toll road example is fair, though I don't know the particulars of this in Australia.

I recently drove from Normandy to Amsterdam and halfway through Belgium I took the wrong exit and ended up adding 20 minutes to the drive. But it was fine.

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