The Washington State Department of Transportation has announced that they are planning on introducing the first Diverging Diamond Intersection (DDI) on I-5 at Marvin Road in Lacey. The DDI was first introduced in 2009 in Springfield, MO and helps improve traffic flow through complex interchanges by minimizing traffic signal phases, shortening wait times, and improving traffic throughput. In addition, this intersection design cuts in half the number of potential conflict points while purportedly improving safety for pedestrians, cyclists, and other road users.

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  1. Could you just use a roundabout.
    they have been proven to work in the whole of europe, asia and australia.

  2. I encountered one of these while on vacation in Utah recently. A little disconcerting to be on the “wrong” side of traffic on the overpass. Am glad I didn’t subconsciously revert to my British driving experience.

  3. It’s an interchange, it’s gotta move traffic, seems to be pretty efficient at that. The problem is building your town around it! The most walkable places aren’t defined by the most-walkable interchanges and the most-walkable stroads…

  4. This should be on your other blog – ” The Suburbanist” where auto oriented sprawl continues to destroy the planet and make it impossible for pedestrians and bike riders to exist.

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