Download the .KMZ to view in Google Earth!
last update Dec. 2013 - http://www.mediafire.com/download/qo07f0wdr8kl72d/Modern%20roundabouts%20(USA).kmz (http://www.mediafire.com/download/qo07f0wdr8kl72d/Modern%20roundabouts%20(USA).kmz)
Modern roundabouts in the lower 48:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2FmodernroundaboutsUSA_zpsa253bea4.jpg&hash=90c285f4166e4494a8af8767a4645ed73249a2cc)
The KMZ file includes roughly 3,200 known modern roundabouts throughout the United States. The modern roundabouts are split up into 3 main categories: local roundabouts, major roundabouts, and interchange roundabouts. In addition, the modern roundabouts are split up based on the number of circulating lanes: single-lane, multi-lane, and triple-lane. The historic imagery feature in GE was used to determine the approximate year of construction. Since there can be large gaps between imagery dates, the year of construction is approximate only.
Not sure how this thread will progress, but any comments or suggestions are welcomed!
I do not see NY 206 / CR 39. (It's right next to I-88.)
EDIT: It doesn't seem to be working when I download it.
^^^ I created another version without time slider data. Time slider files in GE can be difficult to navigate at times. Try this version and see if it helps:
http://www.mediafire.com/download/5kasnb3v4apq70b/Modern+roundabouts+%28USA%29+no+timeslide.kmz
I just don't know where to put the file.
Open it in Google Earth. So save it to somewhere (Desktop, Downloads folder, etc.) and launch Google Earth and go to File->Open then go to wherever you saved the file.
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
I can't open Google Earth. I can use it by clicking the icon on Google Maps, but I can't open Google Earth by itself.
The download is currently in my desktop.
It won't let me open the file with Google Earth either.
I use Mac, so it might not work.
Well, looking at Google's site, it is compatible with Mac OSes... I'm not sure why it won't open in standalone - administrative privileges maybe?
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
The same as the difference between light rail and streetcar: marketing.
And maybe a somewhat better design in some cases.
http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa08006/
PS: if it goes in and around a lake it's a roundabout.
I was opening the wrong thing.
But now, whenever I try to open it, it tries to install it instead.
It has already been installed twice.
I have:
Modern roundabouts (USA) no timeslide.kmz (Google Earth KMZ Document)
googleearth-mac-plugin-intel.dmg.download (Safari download)
googleearth-mac-plugin-intel.dmg (Disk image)
Google Earth Web Plug-in.plugin (Plug-in)
Google Earth (Volume)
A couple new modern roundabouts opened up recently at the exit ramps from US-23 to US-223 in Monroe County, MI...one on each side of the interchange.
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
Open it in Google Earth. So save it to somewhere (Desktop, Downloads folder, etc.) and launch Google Earth and go to File->Open then go to wherever you saved the file.
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
In a word, size. Traffic circles are generally much smaller, typically found on low-volume (neighborhood) streets, and usually lack splitter islands on the approaches. They are more for traffic calming (read: an attempt in passive speed control) rather than an intersection capacity tool.
Rotaries, OTOH, are usually much larger than the modern roundabout. Some places have replaced rotaries with roundabouts and the roundabout fit inside the grassy center of the old rotary. Rotaries operate differently as well, with circulating traffic yielding to entering traffic. Speeds are generally much higher, and in some cases, parking is allowed around the circle as well.
Quote from: DaBigE on December 07, 2013, 10:07:53 PM
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
Open it in Google Earth. So save it to somewhere (Desktop, Downloads folder, etc.) and launch Google Earth and go to File->Open then go to wherever you saved the file.
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
In a word, size. Traffic circles are generally much smaller, typically found on low-volume (neighborhood) streets, and usually lack splitter islands on the approaches. They are more for traffic calming (read: an attempt in passive speed control) rather than an intersection capacity tool.
Rotaries, OTOH, are usually much larger than the modern roundabout. Some places have replaced rotaries with roundabouts and the roundabout fit inside the grassy center of the old rotary. Rotaries operate differently as well, with circulating traffic yielding to entering traffic. Speeds are generally much higher, and in some cases, parking is allowed around the circle as well.
What you're calling a rotary is what Zeffy is calling a traffic circle. Here's Flemington Circle (as well as a second circle just to the west) on Google Maps. https://goo.gl/maps/PrKY3
Quote from: Kacie Jane on December 07, 2013, 10:16:17 PM
Quote from: DaBigE on December 07, 2013, 10:07:53 PM
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
Open it in Google Earth. So save it to somewhere (Desktop, Downloads folder, etc.) and launch Google Earth and go to File->Open then go to wherever you saved the file.
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
In a word, size. Traffic circles are generally much smaller, typically found on low-volume (neighborhood) streets, and usually lack splitter islands on the approaches. They are more for traffic calming (read: an attempt in passive speed control) rather than an intersection capacity tool.
Rotaries, OTOH, are usually much larger than the modern roundabout. Some places have replaced rotaries with roundabouts and the roundabout fit inside the grassy center of the old rotary. Rotaries operate differently as well, with circulating traffic yielding to entering traffic. Speeds are generally much higher, and in some cases, parking is allowed around the circle as well.
What you're calling a rotary is what Zeffy is calling a traffic circle. Here's Flemington Circle (as well as a second circle just to the west) on Google Maps. https://goo.gl/maps/PrKY3
Now after seeing Flemington Circle, I'm not really sure what it would be called, at least based on the current satellite image. It's sized like a rotary, and on some approaches, operates like a rotary (NB & WB, yields to entering traffic), but operates like a modern roundabout (entering traffic yields to circulating).
The one on to the west is sized like a rotary, but operates like a modern roundabout (all yield to circulating).
FWIW, local terminology does not always match engineering terminology. That is one of the biggest hurdles to overcome when presenting a new roundabout project. The first argument I usually hear at a public meeting is how the east coast has "tons of roundabouts that they're ripping out". In actuality, it's rotaries that are being replaced, not modern roundabouts. Wikipedia (http://en.wikipedia.org/wiki/Roundabout) has a fairly good write-up separating the three intersection types.
Roundabout (https://goo.gl/maps/LRsBe)
Traffic Circle (https://goo.gl/maps/0jaJs)
Roundabout (https://goo.gl/maps/PGzW3)
Traffic Circle (https://goo.gl/maps/4qitl)
The circle directly to the west of Flemington Circle is interesting. Looking at the historical imagery from 2009, it's apparent that it operated as a traffic circle with circulating traffic yielding to entering traffic. The circle was recently upgraded so that it now has nearly all the design characteristics of a modern roundabout (all entering traffic yields, raised splitter islands, sharper entry angles to slow entering vehicles, an added truck apron, and upgraded pavement markings). Here is a current aerial of the circle:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2FCircle2013aerial_zps4b78f071.jpg&hash=f222ae0c8af73ca13fc5fdf99602f55d2118d5fe)
Although it may look like a modern roundabout, it doesn't function as one due to its sheer size (that's one thing that didn't change with the upgrade). The diameter of the central island plus the width of the truck apron is approaching 300 feet. Such a large diameter allows for higher circulating speeds which can create a big speed differential between entering and circulating traffic. The whole idea of a modern roundabout is to keep speeds down. Just looking at that aerial, you could drive through the circle at 60 M.P.H. if you really wanted to. I wouldn't consider this a modern roundabout.
Quote from: DaBigE on December 08, 2013, 01:08:58 AM
Quote from: Kacie Jane on December 07, 2013, 10:16:17 PM
Quote from: DaBigE on December 07, 2013, 10:07:53 PM
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
In a word, size. Traffic circles are generally much smaller, typically found on low-volume (neighborhood) streets, and usually lack splitter islands on the approaches. They are more for traffic calming (read: an attempt in passive speed control) rather than an intersection capacity tool.
Rotaries, OTOH, are usually much larger than the modern roundabout. Some places have replaced rotaries with roundabouts and the roundabout fit inside the grassy center of the old rotary. Rotaries operate differently as well, with circulating traffic yielding to entering traffic. Speeds are generally much higher, and in some cases, parking is allowed around the circle as well.
What you're calling a rotary is what Zeffy is calling a traffic circle. Here's Flemington Circle (as well as a second circle just to the west) on Google Maps. https://goo.gl/maps/PrKY3
Now after seeing Flemington Circle, I'm not really sure what it would be called, at least based on the current satellite image. It's sized like a rotary, and on some approaches, operates like a rotary (NB & WB, yields to entering traffic), but operates like a modern roundabout (entering traffic yields to circulating).
The one on to the west is sized like a rotary, but operates like a modern roundabout (all yield to circulating).
FWIW, local terminology does not always match engineering terminology. That is one of the biggest hurdles to overcome when presenting a new roundabout project. The first argument I usually hear at a public meeting is how the east coast has "tons of roundabouts that they're ripping out". In actuality, it's rotaries that are being replaced, not modern roundabouts. Wikipedia (http://en.wikipedia.org/wiki/Roundabout) has a fairly good write-up separating the three intersection types.
Roundabout (https://goo.gl/maps/LRsBe)
Traffic Circle (https://goo.gl/maps/0jaJs)
Roundabout (https://goo.gl/maps/PGzW3)
Traffic Circle (https://goo.gl/maps/4qitl)
It can be explained that traffic circles are one classification of road junction with various subsets that include rotaries and roundabouts–similar to how interchanges are another type of junction, which includes as subsets diamond interchanges, cloverleafs, parclos, SPUIs, DDIs, directional stacks, etc.
In the U.S., however, the terms "traffic circle" and "rotary" are often used interchangeably. In traffic engineering terminology, these are distinguished from "modern roundabouts" by design characteristics which include size, certain design features, and operational patterns.
Rotaries are the bigger circles that tend to have higher speeds. They are not necessarily yield on entry. In some cases they may have no official traffic controls; sometimes the entry or circulating traffic may be controlled by stop signs or traffic signals (like various circles in Washington DC for example). The central island may sometimes feature a small park or other place for pedestrians. These are the junctions that were typical in areas like New Jersey that in some cases are being ripped out or redesigned. The Flemington Circle mentioned previously is a traffic circle or rotary–notice the large size and the couple branches where the circulating traffic is to yield to the entering traffic on some of the heavy movements.
Roundabouts are smaller circles which have lower speeds. Entering traffic always yields to traffic already in the circular roadway. No pedestrians are permitted on the central island. Correctly-designed modern roundabouts at larger junctions will have appropriate channelization so as to funnel circulating traffic to particular exits (preventing continuous circulation, if following the markings).
What DaBigE is calling "traffic circles" above are actually more correctly referred to as "mini roundabouts". These are intersections typically in residential areas with a small island in the center that operate as roundabout, but the surroundings don't permit (and traffic volumes don't require) full roundabout build-out. Splitter islands and channelization are usually absent from mini roundabouts. Mini roundabouts are most often implemented as a neighborhood traffic calming measure.
Quote from: roadfro on December 08, 2013, 03:30:24 AM
What DaBigE is calling "traffic circles" above are actually more correctly referred to as "mini roundabouts". These are intersections typically in residential areas with a small island in the center that operate as roundabout, but the surroundings don't permit (and traffic volumes don't require) full roundabout build-out. Splitter islands and channelization are usually absent from mini roundabouts. Mini roundabouts are most often implemented as a neighborhood traffic calming measure.
Supposedly a mini roundabout has only paint so larger vehicles can go straight through. If there's a solid island it's not a mini roundabout no matter how small it is. Or so say the more anal OSM mappers: http://wiki.openstreetmap.org/wiki/Tag:highway%3Dmini_roundabout#Possible_misinterpretations
Another consideration to factor: roundabouts ALWAYS give traffic within the circle the right-of-way. That's often not the case with traffic circles. Also concur with roadfro's last paragraph..."mini-roundabout" is the generally accepted engineering and planning parlance for what DaBigE called a "traffic circle".
Here's a comparison list (http://www.virginiadot.org/info/resources/round/Differences_between_Modern_Roundabouts_and_Old_Traffic_Circles.pdf) posted by VDOT with info originating from WisDOT about the differences between roundabouts and traffic circles.
The traffic circles Zeffy referred to upthread would not be in the KMZ file because they are not roundabouts nor do they function like roundabouts. Especially in the case of Flemington Circle where traffic in the circle yields to traffic entering on US 202.
Meanwhile...
QuoteI use Mac, so it might not work.
Worked just fine on my Mac.
For tradephoric: out of curiosity, I looked up one roundabout in particular, in Amherst, VA. I understand you're going by the limits of available imagery in Google Earth, but the US 60/BUSINESS US 29 roundabout (http://www.virginiadot.org/info/resources/Roundabout_Facts_-_Week_9.pdf) was built and has been operating as such since 1936. It was upgraded in 2004. You're also missing the long-standing US 15/US 33/VA 231 roundabout in Gordonsville, VA, but I haven't been able to pin down the date of its construction yet.
There's also a brand new roundabout at BUSINESS US 13/VA 126/VA 316 on the Virginia Eastern Shore, just completed last month.
After reading the various responses to my question, I understand that there is a difference between those and roundabouts / rotaries. So, here's some Google Maps views of some other circles in New Jersey that I want your opinion on:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1300.photobucket.com%2Falbums%2Fag88%2FZeffyboy%2FSomCir_View_zpsb20a4785.png&hash=274351e28d291df0c8dd3349488e4e905a5f6530)(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1300.photobucket.com%2Falbums%2Fag88%2FZeffyboy%2FNJ31_Cir_View_zpsc83d8562.png&hash=ca54b6f903deab2df8886d77bf49f28be3a944d8)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1300.photobucket.com%2Falbums%2Fag88%2FZeffyboy%2FUS206NJ70_Cir_View_zpsfdd94ae9.png&hash=93dfeff82e5751553febfb640a9f758aadc10553)(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1300.photobucket.com%2Falbums%2Fag88%2FZeffyboy%2FUS130_Cir_View_zpsc7e26959.png&hash=e0daa1ed460b0c53d1e7fabdff3657157f774513)
Out of all of these, I only think that the US 130 circle (last picture) is a roundabout - the others I can't tell whether they would be classified as a rotary or a traffic circle.
Rotaries are traffic circles. Any difference is made up.
That last one at US 130 and NJ 47 is not a roundabout - note that entering traffic has right-of-way in two places.
Quote from: froggie on December 08, 2013, 10:10:39 AM
For tradephoric: out of curiosity, I looked up one roundabout in particular, in Amherst, VA. I understand you're going by the limits of available imagery in Google Earth, but the US 60/BUSINESS US 29 roundabout (http://www.virginiadot.org/info/resources/Roundabout_Facts_-_Week_9.pdf) was built and has been operating as such since 1936. It was upgraded in 2004. You're also missing the long-standing US 15/US 33/VA 231 roundabout in Gordonsville, VA, but I haven't been able to pin down the date of its construction yet.
I can update the construction year for the Amherst, VA roundabout as 2004 for the next release. Looking at the aerial from 1994, it looked like the circle had the characteristics of a modern roundabout but the aerial was really too grainy to make it out. For some roundabouts, the earliest aerial imagery available was from 2002 and the modern roundabout was already constructed. Since it's generally accepted that the first modern roundabout was constructed in 1990, that leaves a big gap of potential years when the roundabout could have been constructed. I probably wouldn't put that much stock in the construction year. I'd guess 90% are accurate within +/- a year while the other 10% might be a ways off.
I didn't include the Gordonsville, VA circle because i don't believe it's a modern roundabout. One of the entering approaches has stop sign control and you can literally drive through the circle in a straight line.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2Funtitled3_zps1fb74b6d.jpg&hash=5397a1f898f07162775d2c2d5650bf32d3dc5995)
Quote
There's also a brand new roundabout at BUSINESS US 13/VA 126/VA 316 on the Virginia Eastern Shore, just completed last month.
There's a folder called "unknown" that is originally unticked when you open the KMZ file. This folder includes modern roundabouts that are either planned or have been constructed but Google hasn't updated the aerial imagery in the area yet. The roundabout you mention is included in the unknown folder.
Quote from: roadfro on December 08, 2013, 03:30:24 AM
Quote from: DaBigE on December 08, 2013, 01:08:58 AM
Quote from: Kacie Jane on December 07, 2013, 10:16:17 PM
Quote from: DaBigE on December 07, 2013, 10:07:53 PM
Quote from: Zeffy on December 07, 2013, 07:32:12 PM
Nice work though, though I have one question that might be slightly off-topic. What is the difference between a roundabout and a traffic circle? I say this because I expected the Somerville Circle, the Flemington Circle, the Airport Circle, etc. to be in the collection, but they're not, which I guess means they are different than roundabouts. At a precursory glance, there doesn't seem to be a difference, but I feel like it's something small.
In a word, size. Traffic circles are generally much smaller, typically found on low-volume (neighborhood) streets, and usually lack splitter islands on the approaches. They are more for traffic calming (read: an attempt in passive speed control) rather than an intersection capacity tool.
Rotaries, OTOH, are usually much larger than the modern roundabout. Some places have replaced rotaries with roundabouts and the roundabout fit inside the grassy center of the old rotary. Rotaries operate differently as well, with circulating traffic yielding to entering traffic. Speeds are generally much higher, and in some cases, parking is allowed around the circle as well.
What you're calling a rotary is what Zeffy is calling a traffic circle. Here's Flemington Circle (as well as a second circle just to the west) on Google Maps. https://goo.gl/maps/PrKY3
Now after seeing Flemington Circle, I'm not really sure what it would be called, at least based on the current satellite image. It's sized like a rotary, and on some approaches, operates like a rotary (NB & WB, yields to entering traffic), but operates like a modern roundabout (entering traffic yields to circulating).
The one on to the west is sized like a rotary, but operates like a modern roundabout (all yield to circulating).
FWIW, local terminology does not always match engineering terminology. That is one of the biggest hurdles to overcome when presenting a new roundabout project. The first argument I usually hear at a public meeting is how the east coast has "tons of roundabouts that they're ripping out". In actuality, it's rotaries that are being replaced, not modern roundabouts. Wikipedia (http://en.wikipedia.org/wiki/Roundabout) has a fairly good write-up separating the three intersection types.
Roundabout (https://goo.gl/maps/LRsBe)
Traffic Circle (https://goo.gl/maps/0jaJs)
Roundabout (https://goo.gl/maps/PGzW3)
Traffic Circle (https://goo.gl/maps/4qitl)
It can be explained that traffic circles are one classification of road junction with various subsets that include rotaries and roundaboutssimilar to how interchanges are another type of junction, which includes as subsets diamond interchanges, cloverleafs, parclos, SPUIs, DDIs, directional stacks, etc.
In the U.S., however, the terms "traffic circle" and "rotary" are often used interchangeably. In traffic engineering terminology, these are distinguished from "modern roundabouts" by design characteristics which include size, certain design features, and operational patterns.
Rotaries are the bigger circles that tend to have higher speeds. They are not necessarily yield on entry. In some cases they may have no official traffic controls; sometimes the entry or circulating traffic may be controlled by stop signs or traffic signals (like various circles in Washington DC for example). The central island may sometimes feature a small park or other place for pedestrians. These are the junctions that were typical in areas like New Jersey that in some cases are being ripped out or redesigned. The Flemington Circle mentioned previously is a traffic circle or rotarynotice the large size and the couple branches where the circulating traffic is to yield to the entering traffic on some of the heavy movements.
Roundabouts are smaller circles which have lower speeds. Entering traffic always yields to traffic already in the circular roadway. No pedestrians are permitted on the central island. Correctly-designed modern roundabouts at larger junctions will have appropriate channelization so as to funnel circulating traffic to particular exits (preventing continuous circulation, if following the markings).
What DaBigE is calling "traffic circles" above are actually more correctly referred to as "mini roundabouts". These are intersections typically in residential areas with a small island in the center that operate as roundabout, but the surroundings don't permit (and traffic volumes don't require) full roundabout build-out. Splitter islands and channelization are usually absent from mini roundabouts. Mini roundabouts are most often implemented as a neighborhood traffic calming measure.
Not always. In the case of the second traffic circle example I posted, two approaches have a STOP sign. According to FHWA's Mini-Roundabout definition (http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa10007/):
Quote from: FHWAMini-roundabouts are distinguished from neighborhood traffic circles primarily by their traversable islands and yield control on all approaches, which allows them to function as other roundabouts do. Neighborhood traffic circles are typically built at the intersections of local streets for reasons of traffic calming and/or aesthetics. They typically are operated as two-way or all-way stop-controlled intersections and frequently do not include raised channelization to guide approaching traffic into the circulatory roadway. At some neighborhood traffic circles, left-turning vehicles must turn in front of the central island, potentially conflicting with other circulating traffic.
To help promote safe operations, the design of mini-roundabouts generally aligns passenger cars on the approach in such a way as to naturally follow the circulatory roadway and minimize running over the central island to the extent possible. Due to the small footprint, large vehicles are typically required to over-run the fully traversable central island
All of what has been mentioned so far fall under the category of
circular intersections. Traffic circles are more of a gray area, especially with what region of the country you are dealing with. Older traffic circles can be the size of some rotaries and can contain similar features, but usually operate at the speeds of a modern roundabout. Newer traffic circles usually are much smaller, similar to mini-roundabouts.
Quote from: NE2 on December 08, 2013, 11:35:38 AM
Rotaries are traffic circles. Any difference is made up.
If rotaries are traffic circles, then are traffic circles rotaries? :bigass:
No but seriously, I think I'll continue to call them circles, seeing as how that's how New Jersey refers to them:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1300.photobucket.com%2Falbums%2Fag88%2FZeffyboy%2FSigns%2FNJ_Circle_WarningSign_zps3861501e.png&hash=b2d57d63fdd38163ccbde1170e94c7db34ff8173)
For what it's worth, these are the terms I've heard used to describe the small diameter circles found on low-volume streets:
Traffic calming circle (circular island non-transversable)
Neighborhood traffic circle (circular island non-transversable)
Mini-roundabout (circular island transversable)
The KMZ file doesn't include any of these small diameter circles. If the diameter of the central island plus the width of the truck apron was less than 50 feet, it wasn't included.
Quote from: DaBigE on December 08, 2013, 03:20:13 PM
Quote from: roadfro on December 08, 2013, 03:30:24 AM
What DaBigE is calling "traffic circles" above are actually more correctly referred to as "mini roundabouts". These are intersections typically in residential areas with a small island in the center that operate as roundabout, but the surroundings don't permit (and traffic volumes don't require) full roundabout build-out. Splitter islands and channelization are usually absent from mini roundabouts. Mini roundabouts are most often implemented as a neighborhood traffic calming measure.
Not always. In the case of the second traffic circle example I posted, two approaches have a STOP sign. According to FHWA's Mini-Roundabout definition (http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa10007/):
Quote from: FHWAMini-roundabouts are distinguished from neighborhood traffic circles primarily by their traversable islands and yield control on all approaches, which allows them to function as other roundabouts do. Neighborhood traffic circles are typically built at the intersections of local streets for reasons of traffic calming and/or aesthetics. They typically are operated as two-way or all-way stop-controlled intersections and frequently do not include raised channelization to guide approaching traffic into the circulatory roadway. At some neighborhood traffic circles, left-turning vehicles must turn in front of the central island, potentially conflicting with other circulating traffic.
To help promote safe operations, the design of mini-roundabouts generally aligns passenger cars on the approach in such a way as to naturally follow the circulatory roadway and minimize running over the central island to the extent possible. Due to the small footprint, large vehicles are typically required to over-run the fully traversable central island
All of what has been mentioned so far fall under the category of circular intersections. Traffic circles are more of a gray area, especially with what region of the country you are dealing with. Older traffic circles can be the size of some rotaries and can contain similar features, but usually operate at the speeds of a modern roundabout. Newer traffic circles usually are much smaller, similar to mini-roundabouts.
Well... I didn't know there was a difference between mini roundabouts and neighborhood traffic circles. Any small circle I've ever seen on residential streets has functioned as a mini roundabout--all are yield on entry and didn't have a traversable island.
rotary : traffic circle :: pop : soda
roundabout : traffic circle :: diet cola : soda
Quote from: Zeffy on December 08, 2013, 11:29:19 AM
Out of all of these, I only think that the US 130 circle (last picture) is a roundabout - the others I can't tell whether they would be classified as a rotary or a traffic circle.
Quote from: NE2 on December 08, 2013, 11:35:38 AM
That last one at US 130 and NJ 47 is not a roundabout - note that entering traffic has right-of-way in two places.
The 130/47 Brooklawn circle is as far away from the definition of a roundabout that one can get. Not only does 4 roads directly enter the circle; not only does traffic within the circle yield to those entering the circle in two locations, but there's these other differences:
This circle was built 60 years or so ago if not longer. The first modern roundabout appeared in the US in 1990.
There is no stripping to denote lanes within the circle. That in itself isn't absolutely proof of a roundabout, but is frequently found within a roundabout.
There are numerous driveways that lead into and out of the circle directly. I believe I estimated about 6 driveways that one can enter or exit into the circle, along with the 4 enterences & 4 exits using the main roads. And this doesn't even count the low curbing where people can easily drive over as well.
Creek Rd. A modern roundabout would never have an intersecting road so close to a roundabout that isn't technically part of a roundabout. This issue is supposed to be worked on in 2014.
Size. Modern roundabouts would fit in the inner part of most Jersey traffic circles.
Quote from: Zeffy on December 08, 2013, 10:52:46 PM
No but seriously, I think I'll continue to call them circles, seeing as how that's how New Jersey refers to them:
You're still a bit confused about the terminology. NJ calls their traffic circles circles, and their roundabouts roundabouts. A modern roundabout, such as this one in Glassboro (http://goo.gl/maps/2VEmy), or this cluster in the Gloucester/Sickleville area (http://goo.gl/maps/NTmcv), are true roundabouts.
Quote from: jeffandnicole on December 09, 2013, 10:01:34 AM
Quote from: Zeffy on December 08, 2013, 10:52:46 PM
No but seriously, I think I'll continue to call them circles, seeing as how that's how New Jersey refers to them:
You're still a bit confused about the terminology. NJ calls their traffic circles circles, and their roundabouts roundabouts. A modern roundabout, such as this one in Glassboro (http://goo.gl/maps/2VEmy), or this cluster in the Gloucester/Sickleville area (http://goo.gl/maps/NTmcv), are true roundabouts.
When I said "them" I was referring to rotaries and traffic circles, while excluding roundabouts. Though I do appreciate you explaining the key differences between circles / roundabouts in a clear and concise matter. Sorry if I'm a bit slow on the subject. :ded:
Quote from: tradephoric on December 08, 2013, 11:38:59 PMMini-roundabout (circular island transversable)
Are there any in the US?
Quote from: english si on December 09, 2013, 01:42:11 PM
Quote from: tradephoric on December 08, 2013, 11:38:59 PMMini-roundabout (circular island transversable)
Are there any in the US?
Here's one (at least if you ignore the stop sign): http://maps.google.com/maps?ll=28.423335,-81.410472&spn=0.015304,0.028346&gl=us&t=m&z=16&layer=c&cbll=28.423328,-81.410575&panoid=YzvwgDKggVqDdgBfyFJj-A&cbp=12,96.14,,0,11.22
Not coincidentally, this area gets a lot of truck traffic.
Here's a few examples of mini-roundabouts:
https://maps.google.com/?ll=39.215998,-76.810977&spn=0.000421,0.000603&t=h&z=21&layer=c&cbll=39.215998,-76.810977&panoid=rOhOkL-a7DGPMaPMNapO9Q&cbp=12,92.81,,0,8.21 (https://maps.google.com/?ll=39.215998,-76.810977&spn=0.000421,0.000603&t=h&z=21&layer=c&cbll=39.215998,-76.810977&panoid=rOhOkL-a7DGPMaPMNapO9Q&cbp=12,92.81,,0,8.21)
https://maps.google.com/?ll=42.647441,-84.642697&spn=0.000565,0.000603&t=h&z=21 (https://maps.google.com/?ll=42.647441,-84.642697&spn=0.000565,0.000603&t=h&z=21)
https://maps.google.com/?ll=47.513704,-122.347619&spn=0.000734,0.001206&t=h&z=20&layer=c&cbll=47.513612,-122.347699&panoid=ioEzeiU-bZaTLyEh60V72g&cbp=12,3.13,,0,0.9 (https://maps.google.com/?ll=47.513704,-122.347619&spn=0.000734,0.001206&t=h&z=20&layer=c&cbll=47.513612,-122.347699&panoid=ioEzeiU-bZaTLyEh60V72g&cbp=12,3.13,,0,0.9)
Quote from: NE2 on December 07, 2013, 07:54:44 PM
PS: if it goes in and around a lake it's a roundabout.
But will it go 'round in circles? :)
You're missing a couple in Central Georgia:
32°48'51.87"N, 83°43'57.55"W
32°36'52.63"N, 83°36'30.51"W
Also, three under construction/proposed at:
32°51'6.15"N, 83°47'6.71"W (under construction)
32°36'47.04"N, 83°36'12.95"W (under construction)
32°36'47.52"N, 83°36'32.41"W (survey stakes down, likely to be built in spring)
Quote from: hm insulators on December 10, 2013, 02:58:09 PM
PS: if it goes in and around a lake it's a roundabout.
But only if mountains come out of the sky, and they stand there.
The modern roundabouts added to the KMZ pretty much satisfy these 3 simple conditions:
#1. Central island diameter (including the width of the truck apron if it exists) is between 50-200 feet.
#2. Raised splitter islands are included for all major approaches (or have painted splitter islands at the very least).
#3. Drivers must slow down before entering the circle (a driver should not be able to drive straight through the circle).
Here are some examples of circles that I wouldn't consider modern roundabouts because they fail to satisfy at least one of the conditions:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2Funtitled3_zps1fb74b6d.jpg&hash=5397a1f898f07162775d2c2d5650bf32d3dc5995)
Satisfies #1 & #2, but doesn't satisfy #3 (Not a modern roundabout)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2FCircle2013aerial_zps4b78f071.jpg&hash=f222ae0c8af73ca13fc5fdf99602f55d2118d5fe)
Satisfies #2 & #3, but doesn't satisfy #1 (Not a modern roundabout)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2Funtitled8_zpsa815c7e4.jpg&hash=116ac1583b9cd0aa67d2f8d0d11cddf26543d7c9)
Satisfied #1 & #3, but doesn't satisfy #2 (Not a modern roundabout)
The submissions to this thread are very much appreciated. Following these conditions should weed out a lot of the circles that really aren't modern roundabouts.
Quote from: tradephoric on December 11, 2013, 09:32:58 AM
The modern roundabouts added to the KMZ pretty much satisfy these 3 simple conditions:
#1. Central island diameter (including the width of the truck apron if it exists) is between 50-200 feet.
#2. Raised splitter islands are included for all major approaches (or have painted splitter islands at the very least).
#3. Drivers must slow down before entering the circle (a driver should not be able to drive straight through the circle).
Here are some examples of circles that I wouldn't consider modern roundabouts because they fail to satisfy at least one of the conditions:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRoundabouts%2Funtitled3_zps1fb74b6d.jpg&hash=5397a1f898f07162775d2c2d5650bf32d3dc5995)
Satisfies #1 & #2, but doesn't satisfy #3 (Not a modern roundabout)
....
I agree with you about this one not being a modern roundabout, although if you want to be technical about it, the driver following the highlighted route has to come to a stop because there is a very annoying stop sign at that entrance (I go through there fairly frequently). I suppose, though, you could validly say "a driver CAN traverse it without slowing down, it's just that he MAY NOT do so legally"–in other words, but for an artificial constraint (the stop sign) a driver going north could blow through without slowing.
I wouldn't count the one in Caledonia, NY as a modern roundabout, though it does appear to have been painted to operate as one since my last visit. But its physical layout is what it's always been, your typical monument-in-the-middle-of-an-intersection-at-the-center-of-town sort of deal.
(Unless, that is, it's been further reconfigured since both my and StreetView's last visits.)