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I live near Carmel, Indiana, the roundabout capital of the US. Small ones, large ones, figure 8's, figure... double-peanut-looking things with elevated crossove

I live near Carmel, Indiana, the roundabout capital of the US. Small ones, large ones, figure 8's, figure... double-peanut-looking things with elevated crossovers near interstate junctions. They work well and keep traffic moving. But there is a learning curve. Every new roundabout causes a significant jump in crashes for a short time. Though, those crashes tend to be "glancing blows" that cause less serious injuries due to the angle of attack imposes by the roundabout. Smaller cities and towns in Indiana are adopting more roundabouts near congested areas. It's important to introduce them gradually and give drivers time to acclimate. https://www.nytimes.com/2021/11/20/climate/roundabouts-climate-emissions-driving.html https://www.nytimes.com/2021/11/20/climate/roundabouts-clima...

mobilene 4y ago
I'm near Carmel too. I remember when the roundabouts started going in. They replaced four-way stops that backed up for miles at rush hour. The roundabouts made traffic flow SO much better. Now Carmel is replacing some stoplights with roundabouts. This man's opinion is that they are not always better. But so far, they've never been worse.
- kevin_thibedeau 4y ago
  They absolutely suck when a train of cars forms and you can't enter the loop. Those are the dumbest roundabouts in the country. They don't adequately force cars to slow down enough to let gaps develop in the flow.
  - lesuorac 4y ago
    I'm not sure that slowing the cars down would help more. Its much easier to drive literally right behind a car at a slower speed than a higher speed. Afaik, the general trend is to put a stoplight going into the roundabout for the few directions that cause a problem so that the "side streets" get a chance to go.
- smeej 4y ago
  The other stupid thing about Carmel roundabouts is where they put them at every 3rd road crossing when it would have worked absolutely fine just to have the traffic going one way stop, because it's a neighborhood with thoroughfares and cross streets, and there is NEVER traffic on the cross streets. It just makes the thoroughfares slower for no clear reason.
cogman10 4y ago
A failing activity I've seen with roundabouts is when there is no physical barrier but instead just a bump in the road that everyone is supposed to go around. In those cases, a LOT of people end up treating the round about like a 4 way intersection with the worst of all world (because you don't know if someone is going to go against the roundabout rules to turn left). There HAS to be a lump big enough to cause someone to go the right way around.
- fudged71 4y ago
  What if they put a flexible bollard in the center?
  - consp 4y ago
    All anecdotal but hey: The roundabouts I've seen fail (we have many) are those with not enough and too much obstruction. The versions with some form of gradual grace (curved edges around a center platform or lots of grass and a bump) tend to work best. One of the worst ones was a very large one with a meter high round wall as center barrier which caused lots of damage to those who made a mistake. The too small ones are just intersections with minor obstacles to navigate.
    - giantg2 4y ago
      Tall stuff impedes vision. The gental slope around tends to be accommodating for tractor trailers. Short stuff, even just a regular curb inside of the sloped area should be enough to stop cars from driving through it. Some short flowers or plants can help draw attention.
      - landemva 4y ago
        You want to impede vision across so people focus on what is important for their merge.
        giantg2 4y ago
bretthoerner 4y ago
Recent video where roundabouts in Carmel are a big focus, from pedestrian/cyclist POV: https://www.youtube.com/watch?v=rqx6aRCO0MI https://www.youtube.com/watch?v=rqx6aRCO0MI
formerkrogemp 4y ago
> I live near Carmel, Indiana, the roundabout capital of the US. Small ones, large ones, figure 8's, figure... double-peanut-looking things with elevated crossovers near interstate junctions. They work well and keep traffic moving. But there is a learning curve. Every new roundabout causes a significant jump in crashes for a short time. Though, those crashes tend to be "glancing blows" that cause less serious injuries due to the angle of attack imposes by the roundabout. I have a reason to visit Indiana now! Cool. I wonder how I can sell the family on a trip to Carmel or similar city :). The town I grew up started adopting roundabouts as I started driving. They're awesome and so much faster than red lights! They annoy my older relatives and coworkers as well.
- smeej 4y ago
  Carmel is basically a suburb of Indianapolis, and all kinds of things happen at the Indianapolis Convention Center. Surely you can sell your family on one of them!

mobilene 4y ago

I'm near Carmel too. I remember when the roundabouts started going in. They replaced four-way stops that backed up for miles at rush hour. The roundabouts made traffic flow SO much better. Now Carmel is replacing some stoplights with roundabouts. This man's opinion is that they are not always better. But so far, they've never been worse.

kevin_thibedeau 4y ago
They absolutely suck when a train of cars forms and you can't enter the loop. Those are the dumbest roundabouts in the country. They don't adequately force cars to slow down enough to let gaps develop in the flow.
- lesuorac 4y ago
  I'm not sure that slowing the cars down would help more. Its much easier to drive literally right behind a car at a slower speed than a higher speed. Afaik, the general trend is to put a stoplight going into the roundabout for the few directions that cause a problem so that the "side streets" get a chance to go.
smeej 4y ago
The other stupid thing about Carmel roundabouts is where they put them at every 3rd road crossing when it would have worked absolutely fine just to have the traffic going one way stop, because it's a neighborhood with thoroughfares and cross streets, and there is NEVER traffic on the cross streets. It just makes the thoroughfares slower for no clear reason.

cogman10 4y ago

A failing activity I've seen with roundabouts is when there is no physical barrier but instead just a bump in the road that everyone is supposed to go around. In those cases, a LOT of people end up treating the round about like a 4 way intersection with the worst of all world (because you don't know if someone is going to go against the roundabout rules to turn left). There HAS to be a lump big enough to cause someone to go the right way around.

fudged71 4y ago
What if they put a flexible bollard in the center?
- consp 4y ago
  All anecdotal but hey: The roundabouts I've seen fail (we have many) are those with not enough and too much obstruction. The versions with some form of gradual grace (curved edges around a center platform or lots of grass and a bump) tend to work best. One of the worst ones was a very large one with a meter high round wall as center barrier which caused lots of damage to those who made a mistake. The too small ones are just intersections with minor obstacles to navigate.
  - giantg2 4y ago
    Tall stuff impedes vision. The gental slope around tends to be accommodating for tractor trailers. Short stuff, even just a regular curb inside of the sloped area should be enough to stop cars from driving through it. Some short flowers or plants can help draw attention.
    - landemva 4y ago
      You want to impede vision across so people focus on what is important for their merge.
      - giantg2 4y ago

bretthoerner 4y ago

Recent video where roundabouts in Carmel are a big focus, from pedestrian/cyclist POV: https://www.youtube.com/watch?v=rqx6aRCO0MI https://www.youtube.com/watch?v=rqx6aRCO0MI

formerkrogemp 4y ago

> I live near Carmel, Indiana, the roundabout capital of the US. Small ones, large ones, figure 8's, figure... double-peanut-looking things with elevated crossovers near interstate junctions. They work well and keep traffic moving. But there is a learning curve. Every new roundabout causes a significant jump in crashes for a short time. Though, those crashes tend to be "glancing blows" that cause less serious injuries due to the angle of attack imposes by the roundabout. I have a reason to visit Indiana now! Cool. I wonder how I can sell the family on a trip to Carmel or similar city :). The town I grew up started adopting roundabouts as I started driving. They're awesome and so much faster than red lights! They annoy my older relatives and coworkers as well.

smeej 4y ago
Carmel is basically a suburb of Indianapolis, and all kinds of things happen at the Indianapolis Convention Center. Surely you can sell your family on one of them!