My best friend is a highly experienced civil engineer, specialized in designing intersections. His take on roundabouts:
- They are adored by urban planners because they look nice and you can put a statue or fountain in the middle
- They reduce T-bone collisions
However:
- Small fender benders and sideswipes are much more frequent
- They use way more area
- They work where each direction has an approximately equal amount of traffic. However, usually, one direction (north/south, say) has a larger share of the traffic. In those cases, the bulk of traffic all needs to slow down, downshift, turn a bit in one direction and then turn a bit in the other direction for the minority of traffic that's bleeding on or off the main artery. In those cases, a traffic light is better because the timing can be adjusted to the proportion of traffic from each direction (and more flexible since it can be adjusted over time).
- Finally, they're also (mostly) worse for cyclists and pedestrians.
Essentially, they have use cases, especially in small towns, and they're pretty, but they're usually not the right engineering solution.
I live in the UK, which has roundabouts, mini roundabouts, double and triple roundabouts, traffic-light controlled roundabouts, and magic roundabouts. They work perfectly fine.
The difference is that traffic flows very differently in the UK to the US. In fact, the way traffic flows in those two countries captures a lot of their cultural differences. In the US, everything needs a grand overarching theory and imposed order, which is why Americans need traffic lights, and why they’re so keen on a very specific set of liberties that allow them to freely live such similar lifestyles. The UK embraces mild chaos and ruthless pragmatism, with everyone finding locally optimal solutions to their own problems, so things like roundabouts fit well with the national mindset.
American, in an area getting more roundabouts. The two most heartfelt criticisms of roundabouts I've heard are:
- I have to pay attention every time I go through one. (Vs. having your mind elsewhere works fine with traffic lights? That might explain some of those T-bone crashes.)
- Certain multi-roundabout intersections are "because the Road Dept. hates us" horrors to drive through. Most-often cited - <a href="https://www.google.com/maps/@42.5058488,-83.758072,18z?entry=ttu&g_ep=EgoyMDI2MDkxMy4wIKXMDSoASAFQAw%3D%3D" rel="nofollow">https://www.google.com/maps/@42.5058488,-83.758072,18z?entry...
From my PoV, roundabouts are generally a good thing. Mostly because local engineering standards for traffic lights are wretchedly low - so I can get where I'm going far faster through roundabouts.
As a European, that roundabout intersection looks fine? It might be slightly annoying to have to use all three roundabouts if you're exiting the highway northbound and want to take the southbound local road, but with the amount of exits there I can't imagine a junction would be better.
To an American it looks painfully small and slow for coming off a highway and would be overwhelmed often with cars and semi-truck traffic. One semi-truck would stop an entire circles worth of cars with its ass end swinging in and out. And highway travellers are going to be gun shy and not respond as quickly to gaps in the circle after doing 75+mph for an hour or more.
propter_hoc · · focus · HN ↗
- They are adored by urban planners because they look nice and you can put a statue or fountain in the middle
- They reduce T-bone collisions
However:
- Small fender benders and sideswipes are much more frequent
- They use way more area
- They work where each direction has an approximately equal amount of traffic. However, usually, one direction (north/south, say) has a larger share of the traffic. In those cases, the bulk of traffic all needs to slow down, downshift, turn a bit in one direction and then turn a bit in the other direction for the minority of traffic that's bleeding on or off the main artery. In those cases, a traffic light is better because the timing can be adjusted to the proportion of traffic from each direction (and more flexible since it can be adjusted over time).
- Finally, they're also (mostly) worse for cyclists and pedestrians.
Essentially, they have use cases, especially in small towns, and they're pretty, but they're usually not the right engineering solution.
cjs_ac · · focus · HN ↗
The difference is that traffic flows very differently in the UK to the US. In fact, the way traffic flows in those two countries captures a lot of their cultural differences. In the US, everything needs a grand overarching theory and imposed order, which is why Americans need traffic lights, and why they’re so keen on a very specific set of liberties that allow them to freely live such similar lifestyles. The UK embraces mild chaos and ruthless pragmatism, with everyone finding locally optimal solutions to their own problems, so things like roundabouts fit well with the national mindset.
bell-cot · · focus · HN ↗
- I have to pay attention every time I go through one. (Vs. having your mind elsewhere works fine with traffic lights? That might explain some of those T-bone crashes.)
- Certain multi-roundabout intersections are "because the Road Dept. hates us" horrors to drive through. Most-often cited - <a href="https://www.google.com/maps/@42.5058488,-83.758072,18z?entry=ttu&g_ep=EgoyMDI2MDkxMy4wIKXMDSoASAFQAw%3D%3D" rel="nofollow">https://www.google.com/maps/@42.5058488,-83.758072,18z?entry...
From my PoV, roundabouts are generally a good thing. Mostly because local engineering standards for traffic lights are wretchedly low - so I can get where I'm going far faster through roundabouts.
Macha · · focus · HN ↗
AngryData · · focus · HN ↗