[danaris]

I've...never seen a roundabout with lights. Granted, the state I live in doesn't do them much, but I've visited places (like MA) that do them a lot, and they're all very much like European roundabouts, just with inferior signage.

[eesmith]

Here's a rotary in Boston (Sullivan Square) with a traffic light - https://www.google.com/maps/@42.3840002,-71.0744129,3a,75y,9... .

Here's a roundabout in Cape Town (Adderley Street Fountain) with a traffic light - https://www.google.com/maps/@-33.9202591,18.4250697,3a,75y,4... .

Here's one in Cambridge, UK - https://www.google.com/maps/@52.2084812,0.136931,3a,75y,82h,... .

[LoSboccacc]

One in Milan https://www.google.it/maps/@45.480752,9.2227599,3a,75y,111.4...

there are a load there with lights, tram crossing it straight, pedestrian crossing that aren't on a road crossing etc. makes for some fun time crossing one at peak hour, it's not weird at that time to get stuck in one for 10 minutes or more.

[HarryHirsch]

You find that model in areas which in peaktime see too much traffic for a roundabout to work well. If traffic along one pair of roads is too heavy anyone on the minor roads can't get in. So the light serves to gate the heaviest traffic. During off-peak hours the light is off.

[gowld]

The first 2 are lights near the roundabout (where streets cross, or at pedestrian crossings), not in at the roundabout.

[eesmith]

Okay, next roundabout over in Cape Town, no crossing street, no pedestrian crossing - https://www.google.com/maps/@-33.9172315,18.4285489,3a,75y,1... .

[rayiner]

Every roundabout in D.C. has lights: https://www.google.com/maps/@38.9020548,-77.0505595,3a,75y,8....

Some have through streets with lights mixed in with the circle: https://ggwash.org/images/posts/201611-221233-1.png.

[village-idiot]

We have a few roundabouts in my town in SoCal, small ones, and they all have stop signs.

[umichguy]

That's kind of stupid...takes the point away from roundabouts. They're designed to keep the traffic flowing in low /medium conditions when a traffic light or stop sign would bring it to a halt otherwise. Saves on fuel etc.

[bmsleight_]

Above a flow of around 3,600 pcu/hr (passenger car units) per lane, the roundabouts does not balance each direction effectively. (No gaps).

Traffic lights (signals), can help improve flow further in these situations as well as giving pedestrians a safe way to cross.

Part-time signals (only on a peak) can be very effective.

[village-idiot]

These areas are way below 3,600 pcu/h, maybe down in the several hundred to a thousand area. We’re talking residential side streets.

[village-idiot]

You have no idea how frustrated they make me.