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Comment by cameronh90 | Hacker News Reader

Traffic lights aren't the main problem: four way intersections are.

Roundabouts, offset T-intersections and grade separation all make traffic safer by removing conflict points - it's not the removal of traffic lights that improves the safety. Four way intersections put traffic directly on collision paths at high speed, meaning if anyone makes an error (missing the light or otherwise), you have an awful crash.

It's relatively rare in the UK to have four way stops or high speed four way signal controlled intersections. One of the weird things about driving in the US for me was the prevalence of both of those things.

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This the most salient point to me, it is absolutely unbelievable to me that the US continues to use four-way intersections despite the huge risk, loss of life and suffering they cause. They are exceptionally rare in Australia too, if they do exist it is only on a road with a speed limit of 60km/h (at least in my region).

Coincidentally, where I live is known for its many many roundabouts and not only are they safer but they also offer superior cross-way throughput when traffic is heavy. And they allow the "middle" of the intersection to store a chunk of traffic who are protected from full speed impacts while still letting vehicles flow slowly through the perpendicular axis.

I live in Australia too and while roundabouts are OK for low to medium sized road and even larger roads with even traffic they absolutely do not work for heavy and uneven traffic. I have seen a number of large roundabouts become a congestion point once the traffic became heavy and mostly coming from one or two directions. Once they converted those roundabouts to intersections with traffic lights, the congestion eased significantly. So, roundabouts can work but not in all instances.

There's a couple of roundabouts south of Sydney that have traffic lights controlling the entry flow during peak traffic periods. Seem to work well.

Yes, this is one of the few areas that traffic lights excel. I’ve been stuck for 20-30 minutes at a small roundabout in Poland where two highways intersect in a rural area simply because of heavy traffic.

US could stand to gain massively by replacing about 90% of their intersections with roundabouts - but the remaining 10% could probably stay lights and everyone would win.

In the UK, we solve that by putting traffic lights on roundabouts.

Still get the safety advantages of a roundabout but they can carry uneven traffic.

Alternatively, offset junctions are also common.

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