[TheOtherHobbes]

I used to live close enough to this to drive over it occasionally.

When it's busy traffic is literally coming at you from three directions, the geometry isn't obvious or intuitive, and none of the usual rules apply.

It always had glass from collisions on it.

[ggrothendieck]

The video claims roundabouts reduce accidents but according to the experience here: http://www.regionofwaterloo.ca/en/gettingAround/Roundabout-S... collisions involving injury or fatalities did decrease by 51% at intersections that were replaced by roundabouts; however, overall collisions at those intersections increased by 35%.

[GhostVII]

Also no one in Waterloo knows how to use the roundabouts yet, so those numbers should improve eventually.

[theluketaylor]

It's getting better, but now the lack of roundabout knowledge can be exploited to travel much faster. So many people wait in the left lane when going straight through, leaving the right lane free to breeze though.

I do think the non standard roundabouts have become more dangerous now that people are more familiar with the "typical" layout found on ira needles. I was travelling north (or east in the parlance of this crazy city) on Bridge St this weekend. I had just crossed the grand and entered the roundabout intending to take the 3rd exit for Lancaster (left turn). This roundabout is odd due to the lane markings. I was well into the roundabout and had the right of way when a bus entered travelling south (west) on Bridge to turn right on Lancaster. We nearly collided (and if we had it would have certainly been the bus' fault) but I was able to brake in time. I am certain the slightly bizarre layout of this roundabout made it look like I was going to continue on Bridge and therefore it was safe for the bus to enter. I live in this area and this has not been an isolated encounter. The roads all have a single lane entering the roundabout but a special lane appears in the roundabout for taking the 3rd exit for Lancaster. This was likely done to increase traffic flow but results in real confusion for people entering from Bridge the other way. It would likely be much easier if there was just a single lane all the way through the roundabout (like Margaret&Union) so it was clear there isn't room for multiple vehicles in the roundabout at the same time.

[mojuba]

Roundabouts have an extra mental tax on drivers, something that's often disregarded in this kind of debates. You should be more alert, more aware of your surroundings, decisions are tougher to make (move? or not yet?). This 7-in-1 roundabout seems to be taking that to the extreme. I can imagine how uncomfortable and challenging it must be to cross it, especially for drivers who are not familiar with it.

Now compare that to regulated intersections, which come at a price of potentially longer delays of course, but in return have much lower mental tax on drivers.

[gioele]

> Now compare that to regulated intersections, which come at a price of potentially longer delays of course, but in return have much lower mental tax on drivers.

Regular intersections with or without traffic lamps have a measurably higher number of incidents and rate of mortal incidents.

Roundabouts have fewer collision points and force drivers into trajectories that lead to less dramatic impacts.

https://en.wikipedia.org/wiki/Roundabout#Safety has a very illustrative diagram https://en.wikipedia.org/wiki/File:Roundabout_intersection_d... and some cited sources for that claim (claim that fits perfectly with my personal experience living near an urban intersection-turned-roundabout).

[barrkel]

Mental tax is a feature, not a bug. Intersections are dangerous; the more attention you need to pay, the better.

The biggest problem with light signals is that they don't force you to pay attention. Normal-sized roundabouts usually have a big feature in the middle that you'll hit if you don't pay any attention.

[eutectic]

Once you are used to them roundabouts are for the most part pleasant to use, and safer than intersections. It's especially nice not to have to turn across incoming traffic.

[tim333]

Yeah I'd put them as about the 2nd least taxing junction. Slip lanes are probably easiest, then regular roundabouts then stop lights then normal cross roads/intersections.

[Marazan]

Is there really a mental tax for roundabouts over a regular 4 way junction. (Just regular roundabouts, not the magic variety)?

Traffic can only approach you from one direction and traffic on the roundabout has priority, to me it seems much simpler.

[dingaling]

> Traffic can only approach you from one direction

But from two axes in that direction; the entry-lane immediately to the right and then those already in circulation on the roundabout. And often two or more lanes on each of those axes.

When those in the nearest entry lane hold-back, something is approaching in circulation. Change focus to determine its lane, destination and rate of approach and if there is time to enter ahead of it.

For many modern roundabouts the view across the circle is deliberately obscured by vegetation for some reason.

[Marazan]

Two reasons for vegetation

1. Stop people driving straight across. As ridiculous as that sounds it happens too often.

2. Makes driver focus on the traffic approaching from the right Vs traffic entering opposite. (For nations driving on the left)

[joshvm]

I grew up in Swindon and learned to drive there, still go back fairly often (by car). The Magic Roundabout is fine, even at rush hour. I don't think I've ever needed to do a full revolution of it, often I just need to turn right (which you can do a lot faster than on most junctions). That's the beauty of the system - there's an efficient route to all the exits while also letting traffic cross you.

Compared to single roundabouts of a similar size, it's really not that bad. You just treat every little mini-roundabout separately and give way to the right.

It's much less confusing than large roundabouts where you need to anticipate lane markings (which are impossible to see in traffic) or you end up going round for another try.

[verytrivial]

Blocking the view of other roads that also converge on an intersection can have the perhaps surprising effect of reducing accidents, or at least the severity of them. Removing the view of other cars forces drivers to slow down and check when much closer to the intersection. I'm guessing it also reduces lead-foot hubris, but won't stop outright intersection-gamblers. Not all taxes are bad.

(I can't find a reference after an admittedly lame search attempt, sorry!)

[mabbo]

> Roundabouts have an extra mental tax on drivers

So, just like the rest of driving?

Freeway on-ramps, stop lights, pedestrian crossings, bike lanes, one way street... Lots of things are harder mentally until you learn to get used to them.

Roundabouts force you to slow down, however, which is why I think they get such a big backlash at first. But in reality, when built in the right areas, they improve overall traffic flow.

[toppy]

"I can imagine how uncomfortable and challenging it must be to cross it, especially for drivers who are not familiar with it." (specially coming from continental Europe where we have right-side traffic)