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Comment by alkonaut | Hacker News Reader

Knew before I clicked: it's a flat 4-way intersection of two large-ish streets where there is ample space for something else. Hint: draw a small circle in the middle of the intersection and take down the damn stop signs.

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Are you talking about roundabouts? Those are a nightmare for pedestrians

With heavy mixed traffic it's a nightmare for everyone. If pedestrians have the right of way (as they should) and there are a lot of them the whole thing would likely become a permanent traffic jam with almost always one car waiting to turn blocking most of the circle.

here in italy at certain roundabouts we have traffic lights that only work when a pedestrian called them. otherwise, the traffic lights flash a flashing yellow light and as a car you can use the roundabout as if the traffic lights didn't exist.

it's quite useful, if you ask me, it combines the best of both solutions. of course the traffic light has a countdown so if someone presses it immediately after having worked, it will wait for 30sec/1 min before being red again

That fixes the issue for cars but it sounds no better for pedestrians than the intersection in the article, right?

Partially true, given the huge congestion that there is, pedestrian have to wait for the green light even if cars aren't moving due to traffic. However, it is situated in quite an important node of traffic going in/out of the city. in smaller roundabouts we just have zebra crossing without lights, while in more dangerous and big ones (eg more lanes or often has heavy traffic) we have traffic lights

Roundabouts aren't perfect but they greatly reduce the speed of traffic at the crossing point (while increasing the overall throughput of the intersection).

Without looking up statistics (and I'd love to be proven wrong here), I'd be willing to guess that roundabouts may result in some marginal increase in minor accidents but massively reduces fatalities or accidents that leave the pedestrian in the ICU.

Additionally with a roundabout the crossing can be moved a few cars down the street away from the roundabout itself so that cars can have line of sight to safely approach the crossing and pedestrians have time to react to incoming vehicles. On top of that proper placement of crossings allows a normal zebra crossing to be upgraded to a pelican, puffin, or toucan crossing without impeding flow of traffic within the roundabout.

1-lane roundabouts are OK

More than 1-lane and they're a disaster waiting to happen

A disaster for cars, at a slower speed and similar direction than the comparable intersection (and no racing to/from from a light psychology).

So a disaster with significantly better outcomes than a red light runner (with a high speed side swipe or head collision)

Nah, 2 lanes are pretty manageable. Even for a pedestrian. You still only have traffic coming from one direction which makes it easy to see when you can cross.

From a car perspective, it's just a matter of getting in the right lane for the exit you want.

For pedestrians, roundabouts also eliminate left turn lanes, saving ~9' of stroad width to cross and mean only looking one, predictable, direction at a time.

At high traffic times, they can make a pedestrian wait longer. Not so fun when it's cold out.

But otherwise somewhat easier to navigate.

With roundabouts drivers only look to the left and don't come to a complete stop. If you're on foot trying to cross from the other direction good luck.

Yep. Hence the appeal of turning the intersection into a roundabout and pulling the stoplights 3-5 cars from the roundabout and only stopping traffic when pedestrians are present (i.e. puffin and pelican crossing style). It gives cars enough time to turn and then halt with a bright red stop light to catch their attention.

Roundabout + pedestrian stoplight is probably fine. I don't think I've ever seen one and I live not too far from where the article is written.

Seems like it's still worse for pedestrians as they have to wait for the beg button.

Here's a link to the Massachusetts Dept of Transportation's guide on designing/building roundabouts:

https://www.mass.gov/doc/massdot-guidelines-for-the-planning...

It provides solid guidance on how roundabouts should approach crossings to minimize risk of accidents or collisions without impeding traffic.

Probably the best graphic is on page 45, figure 5-13

Crosswalks before the entry to the roundabout, where drivers need to stop anyway; bonus points for a gentle speed hump. Am I missing something?

What kind of roundabout has a "stop anyway"?

Some do have stop signs before you enter, but they should always have at least an implicit yield. Vehicles entering should be prepared to stop in case there's not room to enter the roundabout yet. The real issue with their suggestion is that only being able to cross "before the entry" wouldn't get you anywhere, you have to also cross where cars exit it!

Normally they are for pedestrian crossings. The stop for the incoming traffic will be near where the vehicles yield prior to entering the roundabout but the stop for outgoing traffic is several cars away to allow cars to continue moving in the roundabout.

And because they are pedestrian crossings, they only go red when someone is walking across them and for a few seconds before and after. Which means in most cases they are green 90-95% of the time and only go red for less than a minute at a time.

I'm not against circles in general, but (along with pedestrians) they aren't exactly bike friendly either.

How so?

Both as a pedestrian and driver I prefer roundabouts as they force drivers to slow down to non-lethal speeds and there's typically a one car length of road between the turn and pedestrian crossing, so the cars are already going straight when they cross it.

The only road users who don't mix well with roundabouts are cyclists on cycling lanes, as they get in and out of view too fast.

Drivers also slow down at stop signs.

The issue with roundabouts is that drivers never look to the right while entering. We have a few around me in Long Beach and when you're on foot you may as well be invisible.

Yes. The crossings aren’t solved by the roundabout. But speeds are lowered going into the intersections. The crossings work the same (but may need to move away slightly from the roundabout).

Better: define one street as the thru street and put a stop or yield on the cross-street.

Yes any two streets crossing should ideally either be tiny (like small residential streets where no lights or signs are needed) or only one should be an obvious through street and the other(s) connecting streets. The key is to never have ”grids” of through streets.

zoom out on the map. There is a big roundabout a couple blocks away. It is called "The Circle In Orange."

We should aim at better drivers rather than better intersections, but bad drivers are everywhere.

Years ago I worked in a building on the side of a long straight road. The road ended with a blind curve to the right and 100m before the blind curve there was a pedestrian crossing.

Even though all drivers knew they would need to brake for the blind curve (it was visible and there were signs) the majority of them used to drive very fast and basically did not let people cross the road, only to push very hard on the brakes 10 meters beyond the pedestrian crossing.

The road design is what causes bad or good driving. The road you describe should narrow before the blind curve so the drivers would (often enough unconsciously) slow down before it. For the pedestrian crossing, small islands that separate the lanes and give pedestrians a safe space will help.

https://www.youtube.com/watch?v=bglWCuCMSWc

The bright side of roundabouts and (curbs) annd curves is that they create better (more cautious, observing) drivers, with minor consequences (like hitting a curb).

For lowering the high speed, we can also stack roundabouts, curbs (ie diverge and coverage the road).

The other positive of raised curbs is that we can add shrubbery as a natural traffic barrier, and there are some nice safety impacts from this too, such as reduced road runoff / flash flooding - and environmental factors like shade and cooling.

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