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Thread: Syncing traffic lights: Tech fixes, enduring challenges

  1. #1
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    Default Syncing traffic lights: Tech fixes, enduring challenges

    Syncing traffic lights: Tech fixes, enduring challenges
    https://taprootedmonton.ca/stories/2...ng-challenges/
    “You have to dream big. If we want to be a little city, we dream small. If we want to be a big city, we dream big, and this is a big idea.” - Mayor Stephen Mandel, 02/22/2012

  2. #2
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    Perfect synchronization is impossible, but there are some places that should be easy that still don't work right. Some pedestrian lights for example. These should either be fully synchronized with the nearest intersection, or should give pedestrians priority by turning immediately after the pedestrian hits the button. However, I have seen pedestrians waiting to cross 118 Av at 139 St while I was waiting at a red light at 142 St, only to have the pedestrian light change just as I get a green. That doesn't work well for anyone.

    Another example is 108 St at 111 Av. It uses the same time cycle as the adjacent intersection at 109 St, but it is delayed about 10 seconds from where it should be. The last eastbound vehicle on 111 Av to get through the 109 St intersection before the light turns red will only take 8 seconds to reach 108 St at the 50 km/h speed limit, but the 108 St light stays green for another ~25 seconds. This results in westbound traffic being stuck a red light at 108 St while the 109 St light enters the left turn phase. Simply advancing the 108 St light cycle by 10 seconds would solve this problem.

    There are also examples of lights being synchronized for the wrong speed. You can catch every green on Gateway from 34 Av to Whyte if you go about 75 km/h, but not if you do the 60 km/h speed limit.

  3. #3

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    Hi guys, I used to time some of the signal networks in Edmonton. I suppose you guys can ask away.... I'll see what I have retained as I've moved away from that aspect of Engineering.

    Commenting on the article, the author has definitely been in contact with the traffic signals branch and mostly everything there is accurate and technical terms conveyed in somewhat simple terms - but it misses a few crucial explanations which would make appreciating the intricacies of timing signals a lot better understood (and also a lot less animosity for the folks behind the designs).

    As for Titanium's observations, that's a peculiar observation, but I think the Gateway network might start from Whitemud to Whyte Avenue as opposed to from way back at 34 avenue. But if you're starting at Whitemud, going north at the speed limit and still not hitting the greens majority of the time, that might warrant a call into 311 and ask why. Regarding 111 Avenue, I've dealt with such situations before, and sometimes the most optimized solution doesn't make much sense to the driver on the ground. Although I can't diagnose unless I see the time-space diagram designs...again 311 won't hurt, someone from the traffic signals section will look into it and see if tweaks can be made (I had to deal with dozens of citizen complaints each week).

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    B.ike, do you know much about the SCOOT system? Red Deer uses it. Not sure if good or bad tho.
    When did punk rock become so safe? When did the scene become a joke?
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  5. #5

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    Wouldn't a lot of the problem be the city's ' traffic calming ' . They purposely restrict the flow of traffic so people can't race/ speed .

  6. #6

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    Quote Originally Posted by champking View Post
    Wouldn't a lot of the problem be the city's ' traffic calming ' . They purposely restrict the flow of traffic so people can't race/ speed .
    I've seen it cause light-to-light racing, over and over again. Just makes the races shorter. Also, people will do WAY over the speed limit to try to beat the next red light.

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