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http://www.cmu.edu/homepage/computing/2012/fall/smart-traffic-signals.shtml http://www.cmu.edu/homepage/computing/2012/fall/smart-traffi...

WalterBright 11y ago
That is what I'm talking about. Note that it is a 3 year old article. You'd think environmentalists would get all over "The reductions of 40 percent in vehicle wait time, nearly 26 percent in travel time and 21 percent in projected vehicle emissions realized in this pilot are remarkable," but nope.
- dalke 11y ago
  Roundabouts - that's what I'm talking about. http://www.iihs.org/iihs/topics/t/roundabouts/qanda http://www.iihs.org/iihs/topics/t/roundabouts/qanda and others cite "Retting, R.A.; Mandavilli, S.; Russell, E.R.; and McCartt, A.T. 2006. Roundabouts, traffic flow and public opinion. Traffic Engineering and Control 47(7):268-72". The above URL summarizes the paper as: > A study of three locations in New Hampshire, New York and Washington state where roundabouts replaced traffic signals or stop signs found an 89 percent average reduction in vehicle delays and a 56 percent average reduction in vehicle stops. That URL then goes on to say: > Because roundabouts improve the efficiency of traffic flow, they also reduce vehicle emissions and fuel consumption. Installing roundabouts in place of traffic signals or stop signs has been found to reduce carbon monoxide emissions by 15-45 percent, nitrous oxide emissions by 21-44 percent, carbon dioxide emissions by 23-37 percent and hydrocarbon emissions by 0-42 percent. 6, 11, 12 Constructing roundabouts in place of traffic signals or stop signs reduced fuel consumption by an estimated 23-34 percent. 6, 11, 13 and > A 2005 Institute study documented missed opportunities to improve traffic flow and safety at 10 urban intersections suitable for roundabouts where either traffic signals were installed or major modifications were made to 10 intersections with signals. 14 It was estimated that the use of roundabouts instead of traffic signals at these intersections would have reduced vehicle delays by 62-74 percent. Sounds to me like existing roundabouts at least competitive to state-of-the-art experimental smart traffic signals ... and have the advantage of working even when the power goes out, and don't require more expertise in order to maintain.
  - douche 11y ago
    I call bullshit on roundabouts improving the efficiency of traffic flow in New Hampshire. The roundabouts on US 4 between Portsmouth and Concord will back up for miles, and the Portsmouth traffic circle is an enormous cluster, with more accidents than any signaled intersection I've ever seen (Doesn't help that one of the highest-volume liquor stores in New England is located right on the circle...).
    - dalke 11y ago
      Those are traffic circles or rotaries, not roundabouts. Traffic circles are not roundabouts (nor are they 'traffic calming circles'). Eg, http://www.heraldtribune.com/article/20090621/columnist/906211023?template=printpicart http://www.heraldtribune.com/article/20090621/columnist/9062... (warning: that's the "print" page, rather than having three differet pages): > Often there is considerable confusion about roundabouts and traffic circles or rotaries. People often say that they don't work in the Northeast (especially in New York and New Jersey) and are being removed, so why build them here [in Florida]? ... > A study done by Per Gardner at the University of Maine found that traffic circles have 3.5 to 6.5 times more crashes than roundabouts. ... Because of these growing concerns, the last design reference to traffic circles in the U.S. design standards was in 1965. > Then came roundabouts. The first roundabout in America was built in 1992 at an intersection in Gainesville. Although traffic circles and roundabouts use a circular design, they operate very differently. Traffic circles are very large and are designed for high-speed vehicle operation. Roundabouts are designed as small as possible, 16 to 180 feet wide, and operate at 15 mph to 25 mph. See also http://www.wsdot.wa.gov/Safety/roundabouts/BasicFacts.htm http://www.wsdot.wa.gov/Safety/roundabouts/BasicFacts.htm and http://www.wcroads.org/sites/default/files/pdf/media/Modern%20Roundabout%20Myths.pdf http://www.wcroads.org/sites/default/files/pdf/media/Modern%... .

WalterBright 11y ago

That is what I'm talking about. Note that it is a 3 year old article. You'd think environmentalists would get all over "The reductions of 40 percent in vehicle wait time, nearly 26 percent in travel time and 21 percent in projected vehicle emissions realized in this pilot are remarkable," but nope.

dalke 11y ago
Roundabouts - that's what I'm talking about. http://www.iihs.org/iihs/topics/t/roundabouts/qanda http://www.iihs.org/iihs/topics/t/roundabouts/qanda and others cite "Retting, R.A.; Mandavilli, S.; Russell, E.R.; and McCartt, A.T. 2006. Roundabouts, traffic flow and public opinion. Traffic Engineering and Control 47(7):268-72". The above URL summarizes the paper as: > A study of three locations in New Hampshire, New York and Washington state where roundabouts replaced traffic signals or stop signs found an 89 percent average reduction in vehicle delays and a 56 percent average reduction in vehicle stops. That URL then goes on to say: > Because roundabouts improve the efficiency of traffic flow, they also reduce vehicle emissions and fuel consumption. Installing roundabouts in place of traffic signals or stop signs has been found to reduce carbon monoxide emissions by 15-45 percent, nitrous oxide emissions by 21-44 percent, carbon dioxide emissions by 23-37 percent and hydrocarbon emissions by 0-42 percent. 6, 11, 12 Constructing roundabouts in place of traffic signals or stop signs reduced fuel consumption by an estimated 23-34 percent. 6, 11, 13 and > A 2005 Institute study documented missed opportunities to improve traffic flow and safety at 10 urban intersections suitable for roundabouts where either traffic signals were installed or major modifications were made to 10 intersections with signals. 14 It was estimated that the use of roundabouts instead of traffic signals at these intersections would have reduced vehicle delays by 62-74 percent. Sounds to me like existing roundabouts at least competitive to state-of-the-art experimental smart traffic signals ... and have the advantage of working even when the power goes out, and don't require more expertise in order to maintain.
- douche 11y ago
  I call bullshit on roundabouts improving the efficiency of traffic flow in New Hampshire. The roundabouts on US 4 between Portsmouth and Concord will back up for miles, and the Portsmouth traffic circle is an enormous cluster, with more accidents than any signaled intersection I've ever seen (Doesn't help that one of the highest-volume liquor stores in New England is located right on the circle...).
  - dalke 11y ago
    Those are traffic circles or rotaries, not roundabouts. Traffic circles are not roundabouts (nor are they 'traffic calming circles'). Eg, http://www.heraldtribune.com/article/20090621/columnist/906211023?template=printpicart http://www.heraldtribune.com/article/20090621/columnist/9062... (warning: that's the "print" page, rather than having three differet pages): > Often there is considerable confusion about roundabouts and traffic circles or rotaries. People often say that they don't work in the Northeast (especially in New York and New Jersey) and are being removed, so why build them here [in Florida]? ... > A study done by Per Gardner at the University of Maine found that traffic circles have 3.5 to 6.5 times more crashes than roundabouts. ... Because of these growing concerns, the last design reference to traffic circles in the U.S. design standards was in 1965. > Then came roundabouts. The first roundabout in America was built in 1992 at an intersection in Gainesville. Although traffic circles and roundabouts use a circular design, they operate very differently. Traffic circles are very large and are designed for high-speed vehicle operation. Roundabouts are designed as small as possible, 16 to 180 feet wide, and operate at 15 mph to 25 mph. See also http://www.wsdot.wa.gov/Safety/roundabouts/BasicFacts.htm http://www.wsdot.wa.gov/Safety/roundabouts/BasicFacts.htm and http://www.wcroads.org/sites/default/files/pdf/media/Modern%20Roundabout%20Myths.pdf http://www.wcroads.org/sites/default/files/pdf/media/Modern%... .