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Diverging Diamond Interchange comes to Washington State (2016) [video]

14 points by anonu 9y ago

marx1 9y ago
That means, the bridge will be under British control!
justinator 9y ago
Looks like a pedestrian would have to cross 4 segments of road to just get across the street instead of one? The vid. sort of yadda yadda'd that part.
- Rebelgecko 9y ago
  This style of intersection is somewhat popular in Utah. What often happens is that they replace the left turn lane with a uturn-only light a block or so down the road. If most people are making lefts that may not be a workable solution though
- notatoad 9y ago
  four crossings instead of two, not four instead of one. unless you're simply crossing the cross street, and not actually crossing the highway, which there isn't really any reason a pedestrian would do at that at that intersection. making two 36' crossings is a lot safer than a single 72' crossing. narrowing the crossing width is a good thing in intersection design, even if it takes a bit longer. It's a fairly long walk for for a pedestrian to make, waiting for an extra light isn't going to make a significant change to the crossing length for a pedestrian.
gmiller123456 9y ago
Unfortunately everything I've seen about diverging diamonds appears to me to be more like a marketing campaign for it rather than actual information. They only talk about the positive points of it, and only in abstract terms like the number of conflict points and number of traffic light phases. It seems to me it's trading a separate phase for the left turns, in favor of "everybody has to make a left turn", and those wanting to proceed straight also have to cross traffic again. So I'd imagine this probably does work better for people who wanted to turn left, but worse for people that wanted to go straight. And during low traffic periods, anyone wanting to go straight will have to stop at two lights rather than just having the lights default to green unless a car shows up at one of the sides. Maybe they're better, maybe they're worse, but more likely it depends on a lot more things than this video lets on.

14 points by anonu 9y ago

That means, the bridge will be under British control!

Looks like a pedestrian would have to cross 4 segments of road to just get across the street instead of one? The vid. sort of yadda yadda'd that part.

Rebelgecko 9y ago
This style of intersection is somewhat popular in Utah. What often happens is that they replace the left turn lane with a uturn-only light a block or so down the road. If most people are making lefts that may not be a workable solution though
notatoad 9y ago
four crossings instead of two, not four instead of one. unless you're simply crossing the cross street, and not actually crossing the highway, which there isn't really any reason a pedestrian would do at that at that intersection. making two 36' crossings is a lot safer than a single 72' crossing. narrowing the crossing width is a good thing in intersection design, even if it takes a bit longer. It's a fairly long walk for for a pedestrian to make, waiting for an extra light isn't going to make a significant change to the crossing length for a pedestrian.

gmiller123456 9y ago

Unfortunately everything I've seen about diverging diamonds appears to me to be more like a marketing campaign for it rather than actual information. They only talk about the positive points of it, and only in abstract terms like the number of conflict points and number of traffic light phases. It seems to me it's trading a separate phase for the left turns, in favor of "everybody has to make a left turn", and those wanting to proceed straight also have to cross traffic again. So I'd imagine this probably does work better for people who wanted to turn left, but worse for people that wanted to go straight. And during low traffic periods, anyone wanting to go straight will have to stop at two lights rather than just having the lights default to green unless a car shows up at one of the sides. Maybe they're better, maybe they're worse, but more likely it depends on a lot more things than this video lets on.