In my state, the DOT is considering a lot of roundabouts to replace traffic circles in some intersections.
I don't like them....I know most traffic experts say there are less impact points than on a regular intersection but I feel they are more dangerous due to the fact that there is usually a yield involved and most people don't yield.
You have the right of way if you're in the circle and people coming in on the "spokes" of the circle must yield to the people in the circle. My experience has been that people don't yield. They see a yield sign and that means they don't have to stop or they try to beat you to the punch.
http://www.conndot.ct.gov/media/mainpsa.aspx?url=mms://conndot-video.ct.gov/mediapoint/EngApps/OysterRiver.wmv?sami=&name=Oyster%20River%20Roundabout%20-Traffic%20Simulation (http://www.conndot.ct.gov/media/mainpsa.aspx?url=mms://conndot-video.ct.gov/mediapoint/EngApps/OysterRiver.wmv?sami=&name=Oyster%20River%20Roundabout%20-Traffic%20Simulation)
do you think yield means stop? It doesn't, it simply establishes rules about who has the right of way. I prefer roundabouts to four-way stops.
EDIT: Of course there's other extremes :-P
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Quote from: Master son on July 04, 2009, 09:41:08 PM
do you think yield means stop? It doesn't, it simply establishes rules about who has the right of way. I prefer roundabouts to four-way stops.
No it doesn't mean stop....but if I'm in the circle and somebody comes in from the side, THEN it means stop and from my experience most people don't and that's why I don't like them.
Quote from: froggie on July 04, 2009, 11:29:56 PM
That speaks more to poor driver education than it does to roundabout design.
Well that's the thing, if you have a two-pole YIELD sign on both side sof the "spoke"...people still try to beat you to the punch. That is correct, poor drivers but we ain't gonna change that. No matter how much signage, lighting etc we have...unfortunately. plus the ones around here are small.
Poor drivers think that yield means you can go no matter what. But, they're wrong....
Most of you know what yield means... so I won't go into detail.
I think roundabouts take longer to drive through so if you're in a hurry, don't expect to run right through the roundabout.
Western Colorado, along the I-70 corridor, is home to dozens of roundabouts. Despite people disliking them, I think they work out better because:
- It reduces the number of high speed crashes at intersections (caused by running a stop sign, lower speeds thru the intersection, etc). In fact most accidents occurring in roundabouts involve speeds under 10 MPH, which means less chance for damage &/or injury
- In most cases, traffic can pass through a roundabout faster than an all-way stop or traffic light intersection.
- All turns into and out of roundabouts (in North America) are all right turns.
- U-turns at intersections are safer when using roundabouts vs. a normal crossroad intersection.
Disadvantages:
- Those who are uneducated about the use of roundabouts (they are the ones who wait until there is no traffic on the [smaller] roundabouts, they come to a complete stop before entering a roundabout even though it is clear for them to enter, or they stop inside the roundabout to let spoke traffic in.
- Larger trucks and vehicles may have a tougher time navigating smaller roundabouts, adding to wait times.
- In multi-lane roundabouts, some drivers will ignore lane markings and make their turnoffs from the inner hub lane to their exit, crossing a lane or two of traffic.
- Signage for approaching the roundabout, or proper signage within the roundabout can be confusing, or non-existent, which can lead to the aforementioned disadvantages.
As with a lot of things, it's situation specific. There are times when it's better to have a roundabout than an intersection. There are times when it's not.
One situation where they're useful is when you have a three way intersection with somewhat evenly spaced spokes (i.e., not T shaped, but more Y shaped) where traffic distribution between spokes is somewhat even - and thus, there's no clear lesser spoke to give a stop sign while the other two move freely between each other, and three way stops... no (I despise three way stops, but that's another topic).
But there are certainly situations where thy are used whjere they shouldn't be.
If you start getting multi-lane roads feeding in, that implies that you'd want a multi-lane roundabout... which is bad, because the inner lane is dead space since everyone needs to exit from the outside.
If the geometry is such that it'd need to be signalized, than you might as well just not bother - because then you've defeated the entire purpose of having a roundabout (that traffic can move through without ever encountering a stop sign or red light).
And then you have cases where tight narrow roundabouts are put into otherwise large wide open intersections as a traffic calming measure... sorry, but that's just wrong.
In our area, selected intersections have been converted to roundabouts. In all fairness, they're not that hard to navigate, and are quite fine. Here are the locations of known (personally) roundabouts in Metro Detroit.
Oakland County
- Maple Road @ Drake Road
- Maple Road @ Farmington Road
- 14 Mile Road @ Farmington Road
- Bogie Lake Road @ Cooley Lake Road
Macomb County
- 26 Mile Road @ M-53
- 19 Mile Road @ Romeo Plank Road
I like roundabouts. Sure beats the heck out of waiting at a red light. They aren't all that difficult to drive through once you've done it a few times. Wisconsin is installing more and more of them all the time. WisDOT is rebuilding and expanding US 41 on the west side of Green Bay, and every interchange is getting roundabouts at the ramp terminals.
Roundabouts are well established over here. Aa a kid in the 80's I saw many traffic light intersections converted to roundabouts. However since then traffic has grown and some of these roundabouts have dominant traffic flows so traffic trying to join downstream of the dominant flow ends up waiting for ages for a suitable gap to pull into. As a result some of these have become signalised where the roundabout contains traffic lights like in the picture below. The only problem with this is on small roundabouts the traffic will back up to the entry behind.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fsabre-roads.org.uk%2Fgallery%2Falbums%2Fuserpics%2F10004%2FCNV00017.jpg&hash=ba59ce351547116132b838310bd666618fae5f58)
Another problem with roundabouts is when they're used on the mainline of fast roads. This (http://maps.google.co.uk/?ie=UTF8&ll=52.480755,-1.70802&spn=0.005012,0.018024&t=k&z=17) roundabout replaced a gap in the median a few years ago. The result is traffic on the divided highway now has an extra obstacle to negotiate and the geometry of modern roundabouts, especially the approaches, is quite shocking.
If they are used properly such as in situations where traffic can't emerge from side streets or where traffic lights cause traffic to be stationary for ages then they're fine, but as Duke87 says when they interrupt traffic on main roads they just cause stop starting all the time and the associated wear and tear on cars.
the only major problem with roundabouts is the right of way rules. They vary between roundabouts, rotaries, and traffic circles, and sometimes can get fairly arcane. Here is Massachusetts law:
QuoteIf the rotary has a single lane, you must enter from the right lane of the road you are coming from and exit onto the right lane of the road you intend to travel on. If the rotary has multiple lanes, look for signs to help you choose the proper lane. If there are no signs, you should do the following:
- For a quarter-turn, or to continue straight ahead, enter the rotary from the right lane, stay in that lane, and exit onto the right lane.
- For a three-quarter-turn, or a U-turn, enter the rotary from the left lane, travel through the middle or inner lane, and exit onto the right lane. If coming from a road with a single lane, you should stay in the right lane for the entire turn.
does anyone in Massachusetts actually know that? Also, how is it possible to enter the rotary from the left lane, unless one is already on the inside island? It's pretty arcane.
This sort of area is the only place I can think of offhand where traffic staying in a given lane must give right of way without being explicitly signed to do so - in all other cases, traffic that is changing lanes has to give way.
Some roundabouts have two lanes leading up to it, my city has a 3-lane roundabout at a freeway interchange.
Turboroundabouts are now replacing the oldstyle multilane, undivided roundabouts in the Netherlands. It means you have to chose the right lane before you enter it. It preferrably needs overhead signage, and can be a solution on roads with an AADT up to 25,000
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I like roundabouts. When used in low or medium volume situations, they reduce delay. I just wish more people could navigate them appropriately. That will come with time and more installations.
Chris, that "turbo" roundabout actually looks like it manages the lanes pretty well. The only thing is that it probably doesn't support a two-lane approach on all four legs. But still, something that I wouldn't mind seeing at some applications in the US.
Quote from: Duke87 on July 05, 2009, 03:22:34 PM
If you start getting multi-lane roads feeding in, that implies that you'd want a multi-lane roundabout... which is bad, because the inner lane is dead space since everyone needs to exit from the outside.
Generally, you don't want to go more than two lanes within the roundabout itself. There's a few roundabouts in Las Vegas where each approach has three lanes. However, the rightmost lane is a right turn only and is physically separated from the actual circular roadway of the roundabout. Thus, the center lane of the approach can be used for through traffic and the left approach lane is for through, left and U turns.
I generally like them, and I am happy to see NY putting in more (like the several near Northway Exit 12 and at US 9/NY 67 in Malta).
There are some unusual ones I have driven quite a bit along Route 33 in Chicopee, MA:
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=chicopee,+ma&sll=37.0625,-95.677068&sspn=43.123021,58.447266&ie=UTF8&ll=42.180547,-72.577465&spn=0.004945,0.007135&t=h&z=17 (http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=chicopee,+ma&sll=37.0625,-95.677068&sspn=43.123021,58.447266&ie=UTF8&ll=42.180547,-72.577465&spn=0.004945,0.007135&t=h&z=17)
MA 33 is signalized and passes straight through here and at another intersection just to the north. 33 and the side streets have left turn arrows. When traffic is light and you see you're going to catch the red on 33, you can loop around the side of the rotary to get through without a wait. Traffic generally backs up too much at busy times, both on 33 and on the rotary itself, to do this when it's busy.
An example of a traffic circle that used to be a mess but is much improved now is the Latham Circle at NY 2/US 9 in Latham, NY.
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=latham+ny&sll=42.180547,-72.577465&sspn=0.004945,0.007135&ie=UTF8&ll=42.748147,-73.760995&spn=0.00245,0.003567&t=h&z=18&iwloc=A (http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=latham+ny&sll=42.180547,-72.577465&sspn=0.004945,0.007135&ie=UTF8&ll=42.748147,-73.760995&spn=0.00245,0.003567&t=h&z=18&iwloc=A)
One nice feature that's been in place for as long as I can remember is that US 9 passes through without stopping using an underpass of the circle. It's only the NY 2 through traffic and traffic entering or exiting NY 2 for US 9 that needs to use the circle. Several years ago now, the lanes inside the circle were redrawn from having 2 lanes all the way around, meaning that someone on the inside wanted to exit while someone on the outside wanted to keep going around. Not good. It now has 2 lanes on the north and south parts of the circle, which carry NY 2 through traffic, but just one lane on the east and west parts of the circle. The circle is also now well-signed and has clear pavement markings and just works a lot better than it did before.
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^^^
If you're going to allow traffic straight through without using the circle, then I prefer the latter approach with the grade separated US 9. The other one, along with one that was shown from New Jersey IMHO defeats the whole purpose of a traffic circle/roundabout.
We don't have any roundabouts where I live, although the project that's converting four-lane NY590 in Irondequiot to a two-lane parkway is supposed to have roundabouts to replace the current signalized intersections. The only actual roundabout I've driven through is the one off of Exit 19 of the NY Thruway...the one connecting the Thruway with NY28 (and I-587...but that really shouldn't have an Interstate designation :D). I found it very easy and pleasant to drive through, and it made for a nice transition from the Thruway onto NY28 to head into Kingston. :D
All in all, I quite like having more and more roundabouts showing up...I'd much rather go around a roundabout than be stuck waiting forever at a light at a busy intersection without a left turn arrow! :-D
An advantage of roundabouts is that trucks can make U-turns quite easy.
Quote from: cu2010 on July 07, 2009, 04:08:53 PMthe project that's converting four-lane NY590 in Irondequiot to a two-lane parkway is supposed to have roundabouts to replace the current signalized intersections.
You can view the plans here (http://www.irondequoit.org/content/view/236/1015/). The roundabout at Titus Ave (where NY 590 becomes Sea Breeze Drive) will have two lanes - the right will be for accessing Titus Ave Ext and Sea Breeze Drive, while the left will the the main lane for the roundabout; in the other direction, NY 590's right lane will come from a right turn directly off of Titus Ave.
http://www.youtube.com/watch?v=A75paG3qjZw