The roundabout thread

[Glodenox]

When you add lining for the cars coming from outside the roundabout, it visually looks like they have right of way, which they don't (talking about those black lines added on the image). Also, the angle of making that turn to the right is way too sharp for it to be a logical option to a driver. I personally prefer not having any arrows on the "straight" and "right" directions on those lanes, but an overhead sign telling people to use that lane for a certain destination. This is of course only useful for big and complex roundabouts, not the regular ones with 2 lanes.

[tradephoric]

Here's a short video of a confused motorist traversing a roundabout in the wrong direction.

[joshsam]

lol, how do you even do that not on purpose?

[shpirtkosova]

Maybe its a British pensioner.... or woman.

[AtD]

Originally Posted by geor

For better understanding it is necessary to have additional similar vertical signs too

I think given the number of roundabouts, the size of them and the volumes of traffic many of them carry, that's a bit of overkill.

Really you just need some of these:


And some of these:



...and plenty of <<<< signs.

There's plenty of two lane roundabouts in Australia with no advance warning at all - you may not realise its a roundabout until you actually get to the intersection. These definitely need better warning. There's one near where I used to live where the only advance warning that it was a roundabout (and not just a general hazard) was a single direction sign: http://g.co/maps/qa7r8 and then a completely wrong right turn sign! http://g.co/maps/tazpr

[joshsam]

Roundabout near where I live:


http://www.kumpen.be/new/images/dbim...puntstayen.jpg

[Nexis]

Washington State has gone mad with rounabouts...

image hosted on flickr

I-5, D Street roundabouts in Blaine by WSDOT, on Flickr

image hosted on flickr

SR 539, River Road roundabout near Lynden by WSDOT, on Flickr

image hosted on flickr

SR 539, Ten Mile Road roundabout near Bellingham by WSDOT, on Flickr

image hosted on flickr

I-5, Portal Way roundabout in Ferndale by WSDOT, on Flickr

image hosted on flickr

SR 542, SR 9 roundabout in Deming by WSDOT, on Flickr

image hosted on flickr

SR 539, SR 544 Roundabout near Lynden by WSDOT, on Flickr

image hosted on flickr

SR 548 Roundabout - Aerial by WSDOT, on Flickr

image hosted on flickr

10 of 11: Aerial view of truck driving through roundabout by WSDOT, on Flickr

image hosted on flickr

Aerial view of roundabout in Anacortes by WSDOT, on Flickr

image hosted on flickr

Aerial view of roundabout in Anacortes by WSDOT, on Flickr

[joshsam]

They look good. Fit in well. It will reduce travel time and avoid a lot of collisions

[joshsam]

IKEA, Liège, Belgium


http://www.eloy.be/media/cms/travaux...ns/619_web.jpg

[dmjar]

This is a good hybrid between a junction/dual carriageway and a roundabout.

http://maps.google.co.uk/maps?q=stre...d+Kingdom&z=17

[Tom 958]

Originally Posted by dmjar

This is a good hybrid between a junction/dual carriageway and a roundabout.

http://maps.google.co.uk/maps?q=stre...d+Kingdom&z=17

Looks more like a dog's breakfast to me.

Here are some not-very-good photos of the Emory Village roundabout near Atlanta. It replaces a notorious traffic light at this five-way intersection, and it seems to be an aesthetic and operational success, combined as it was with a variety of streetscape improvements for this walkable retail/restaurant district.

There are very few roundabouts in Atlanta, but here there are two within a couple of blocks of each other-- I think the western Lullwater roundabout was the first true roundabout in metro Atlanta. When it was first built, the left lane of westbound North Decatur Road was terminated before the roundabout by means of a surprise compulsory left turn into an apartment complex, but the Emory Village roundabout project also restriped that part of North Decatur Road from four lanes to 2 + 2WLT + bike lanes, eliminating the surprise compulsory left turn.







I saw an 18 wheeler get stuck in the roundabout, though it wasn't a fair test: the truck apron had just been poured and was blocked off from traffic. Fortunately one of the construction workers explained to the truck driver that he could get to where he was going by making a right turn and using a side street to bypass the roundabout.

[ChrisZwolle]

Atlanta appears to be a somewhat hostile environment for roundabouts. It has a lack of a dense freeway network, which means the arterials are wide and busy, unfavorable for roundabouts. Though metropolitan Atlanta is less dense than nearly all other major U.S. metropolitan areas, which means there could be more space for roundabouts than in say Dallas or Miami. The main problem with fitting roundabouts in an existing road network is acquiring a right-of-way. Roundabouts simply require more space than traffic signals.

[brewerfan386]

Business WIS-29 and WIS-124 in Chippewa Falls
image hosted on flickr

Courtesy of Dougtone
Image link
Google Maps:http://goo.gl/maps/E6KA

[TheCat]

I recently returned from a trip to Israel, and it seems like almost every intersection in my home town was replaced with a roundabout. They are everywhere. In general, in Israel there are probably thousands of them now outside of dense city centres (like Tel Aviv), where there isn't a lot of space for them.

This was also my first time driving outside of North America, and I must say, I loved the roundabouts for the most part. Very efficient and reduce the annoyance of frequent stops at unnecessary stop signs and lights.

Originally Posted by AtD

...
There's plenty of two lane roundabouts in Australia with no advance warning at all - you may not realise its a roundabout until you actually get to the intersection. These definitely need better warning. There's one near where I used to live where the only advance warning that it was a roundabout (and not just a general hazard) was a single direction sign: http://g.co/maps/qa7r8 and then a completely wrong right turn sign! http://g.co/maps/tazpr

This seems like it could be really dangerous, but I suppose that it depends on local regulations and road layouts.

In Israel, there are "circular" intersections that look very similar to roundabouts (although usually the approach angle is not as narrow), but they actually are not - some approaches inside the so-called roundabout have yield signs.

In Israel, if upon approaching an intersection, a sign like the one below is not present, one must continue without yielding to anyone, even if the intersection looks like a roundabout:

(The sign would be in the opposite direction of course, since in Israel driving is on the right side)

Also, yield signs at entrances to roundabouts are usually not present, and are not necessary - the above sign is enough.

I may post some pictures that I made on my trip later on.

[solchante]

A German roundabout

[I-275westcoastfl]

Originally Posted by ChrisZwolle

Atlanta appears to be a somewhat hostile environment for roundabouts. It has a lack of a dense freeway network, which means the arterials are wide and busy, unfavorable for roundabouts. Though metropolitan Atlanta is less dense than nearly all other major U.S. metropolitan areas, which means there could be more space for roundabouts than in say Dallas or Miami. The main problem with fitting roundabouts in an existing road network is acquiring a right-of-way. Roundabouts simply require more space than traffic signals.

Not necessarily true.. I mean the intersections with 3x3 lanes and the 2 lanes for turning left and possibly another lane for right turns can get pretty wide.

[ChrisZwolle]

You can't replace intersections with 9 lanes at traffic signals with roundabouts anyway. The upper limit for a roundabout is about 25.000 vehicles per day.

[geor]

Originally Posted by ChrisZwolle

You can't replace intersections with 9 lanes at traffic signals with roundabouts anyway. The upper limit for a roundabout is about 25.000 vehicles per day.

Roundabouts capacity depends on many factors (balanced or not traffic flow, entry capacity, circulating capacity, existence of shortcuts, number of lanes, lane width, diameter, driver behaviour, design, …….etc.).
Applicable parameter is veh/h not AADT. So, capacity range of roundabout varies from 1300 to 5000 veh/h (from 1 lane - 3 lane roundabouts).

[ChrisZwolle]

Multi-lane roundabouts don't work as well as turbo roundabouts, so for regular roundabouts, 2 lanes is about the limit, 3-4 lanes at so-called "turbo squares", which are often traffic light-controlled, where traffic flows in a roundabout-like manner, but function as traffic light-intersections.

Like the "Polish roundabout":

[mgk920]

Originally Posted by brewerfan386

Business WIS-29 and WIS-124 in Chippewa Falls
image hosted on flickr

Courtesy of Dougtone
Image link
Google Maps:http://goo.gl/maps/E6KA

Why would one want to drive into the lake? Wouldn't 'Eau Claire' be a better 'control' for that sign?

Anyways, that roundabout replaces a very NASTY trumpet interchange that was used by WI 29 (WI 29 made a turn there) before the WI 29 bypass freeway was built a few years ago. In fact, IMHO, that roundabout replacing the trumpet there would have been a HUGE improvement - even without the WI 29 bypass freeway.

Mike