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Old 01-23-2014, 04:02 PM
 
Location: Foot of the Rockies
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Can I ask what the purpose of this thread is? We have quite a few roundabouts here in Boulder County.
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Old 01-23-2014, 06:21 PM
 
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To debate how effective they are. True, few of us are traffic engineers, but how well do they move traffic? While they are not universally applicable they can be a good alternative. Probably where you have two, 6-lane streets crossing they don't work well.
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Old 01-23-2014, 07:28 PM
 
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Quote:
Originally Posted by NewJerseyMemories View Post
Haha.

Actually, many of the infamous New Jersey traffic circles have either been modified or are gone entirely (the scary Ledgewood Circle, for example). The Livingston circle wasn't that bad.
The Livingston circle (Eisenhower Parkway, NJ 10, and Northfield) still exists, although one road off of it (Old Road) is closed.
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Old 01-23-2014, 07:35 PM
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Location: Long Island / NYC
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Quote:
Originally Posted by pvande55 View Post
To debate how effective they are.
I thought it was just to make a list for the sake of it. Didn't think there was any deeper point.
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Old 01-26-2014, 06:15 AM
 
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NJ traffic circles shouldn't be confused with a roundabout. Circles are much larger in diameter and operate at higher speeds. They were great when the population of NJ was around 3 million. 5 million people later and they're pretty dangerous - so the state has been getting rid of them over the last 10-15 years.

Manasquan Circle - http://goo.gl/maps/sQoNC

Camden County College roundabout (even this is rather large for a roundabout) http://goo.gl/maps/Sl4n0

NJ jughandle - http://goo.gl/maps/d5M18
A lot of state highways in NJ are divided with a "Jersey barrier". In effect it's like a freeway with lights - not unlike Independence Blvd in Charlotte. You don't make turns but rather you "exit".

This is a safety feature (turning movements are when most crashes occur - especially left hand turns) but it also helps to move a much heavier volume of traffic in a shorter amount of time. In addition to eliminating people slowing down in the left lane to make turns all of the signal phases for left turns are eliminated. It might cost you a little extra time if you're trying to "turn left" but it saves a significant amount of time for the main line flow of traffic.
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Old 01-26-2014, 06:46 AM
 
Location: Idaho
836 posts, read 1,382,940 times
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Quote:
Originally Posted by Dirt Grinder View Post
If you ever need some cheap entertainment, sit and watch how folks drive through a roundabout for fifteen minutes.
HA-or a 4-way stop.

I like roundabouts because most people can keep moving, although some just don't get it.
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Old 01-26-2014, 07:30 AM
 
Location: Arizona
5,510 posts, read 6,165,367 times
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Quote:
Originally Posted by drive carephilly View Post
NJ traffic circles shouldn't be confused with a roundabout. Circles are much larger in diameter and operate at higher speeds. They were great when the population of NJ was around 3 million. 5 million people later and they're pretty dangerous - so the state has been getting rid of them over the last 10-15 years.

Manasquan Circle - http://goo.gl/maps/sQoNC

Camden County College roundabout (even this is rather large for a roundabout) http://goo.gl/maps/Sl4n0

NJ jughandle - http://goo.gl/maps/d5M18
A lot of state highways in NJ are divided with a "Jersey barrier". In effect it's like a freeway with lights - not unlike Independence Blvd in Charlotte. You don't make turns but rather you "exit".

This is a safety feature (turning movements are when most crashes occur - especially left hand turns) but it also helps to move a much heavier volume of traffic in a shorter amount of time. In addition to eliminating people slowing down in the left lane to make turns all of the signal phases for left turns are eliminated. It might cost you a little extra time if you're trying to "turn left" but it saves a significant amount of time for the main line flow of traffic.
Longer than that actually. North Jerseyans may recall the notorious traffic circles on Route 23 in Wayne and Riverdale. Especially Ratzer Rd. They were removed around the late 80s or early 90s. And a few years before that the state placed traffic lights on the highway sides of the circles to create breaks in the traffic so folks had a fighting chance to get on from the side roads.

I never had an issue with the jug handles, except a couple of times when some idiot (usually with NY plates) would try to turn left anyway and either cause or almost cause a pileup.
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Old 01-26-2014, 02:51 PM
 
4,023 posts, read 3,277,758 times
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Quote:
Originally Posted by jade408 View Post
Berkeley has lots and lots, particularly in the bike boulevards to keep car traffic out. Oakland has some, one in my own street.
I don't know if Berkeley has any actual roundabouts. The few I've seen were just simple and very badly thought out traffic circles.

Quote:
Originally Posted by pvande55 View Post
To debate how effective they are. True, few of us are traffic engineers, but how well do they move traffic? While they are not universally applicable they can be a good alternative. Probably where you have two, 6-lane streets crossing they don't work well.

Contrary to many peoples’ perceptions, roundabouts actually move traffic through an intersection faster, and with less congestion on approaching roads. Roundabouts promote a continuous flow of traffic. Unlike intersections with traffic signals, you don’t have to wait for a green light at a roundabout to get through the intersection. Traffic is not required to stop – only yield – so the intersection can handle more traffic in the same amount of time.


Roundabout studies by Kansas State University have measured traffic flow at intersections before and after conversion to roundabouts. In each case, installing a roundabout led to a 20 percent reduction in delays. The proportion of vehicles that had to stop – just long enough for a gap in traffic – was also reduced.

Safety benefits

The 2013 safety study through the Univ. of Wisconsin TOPS lab was cited previously showing that the 30 roundabouts involved in that study showed a 38 percent reduction in fatal and injury crashes and a 12 percent increase for all crashes. Other safety studies have been cited as well to include the Insurance Institute for Highway Safety and the National Cooperative Highway Research Program (NCHRP) 572*, with both studies indicating that roundabouts reduce the severity of crashes at intersections where stop signs or signals were previously used for traffic control.

Roundabouts - Benefits - WisDOT

Well-designed roundabouts are cheaper and safer. Low but steady speed and steady flow is not only safer but more efficient at moving traffic than the high-speed abrupt stop and go traffic that you get with stop lights. They can also provide an aesthetic improvement.
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Old 01-26-2014, 04:02 PM
 
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Roundabouts are effective. The only issue with them is most people don't understand what yield means. Yield does not mean stop, you give way to traffic before proceeding. If there are no traffic, you may enter without stopping.
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Old 01-26-2014, 04:08 PM
 
3,463 posts, read 4,561,979 times
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Quote:
Originally Posted by Dirt Grinder View Post
If you ever need some cheap entertainment, sit and watch how folks drive through a roundabout for fifteen minutes.
In the world of bicycles and ped/alt trans promotion, a lot people love these and will cite all kinds of statistics and anecdotal evidence from europe as to there effectiveness. I however agree with you. Here in the USA, they just dont work. Im sure insurance companies welcome them with open arms as they blanket raise all peoples insurance in areas that have them. We just arent a society that can handle them on a large scale. Will never happen, either
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