To The Point

  • Tue December 21, 2010

    Newsworthy Solutions: The Diverging Diamond Interchange


    The country (California especially) is at a point where we don't have a lot of money for highway infrastructure, but we've still got plenty of issues like congestion, maintenance, and so on. One of the things we've been concentrating on at Point C is investigating alternative solutions that are cost effective and relatively unintrusive. 

    The diverging diamond interchange is one of these solutions. It's a little weird to see at first, because it requires you to drive on the other side of the road as you cross the over or underpass. In short, the two directions of traffic that are coming off the freeway cross over to the other side using both sides of the bridge at the freeway, but only one direction goes at a time.

    Sounds complicated, but it's actually a great safety improvement because it eliminates left turns that cross oncoming traffic and gets rid of horizontal road curvature that can be the source of accidents. In addition, everyone moving is controlled by a light, rather than yielding. It also reduces delay by using short, two-phase signals.

    Here's a video showing how it works:

    Sprinfield, Missouri is the first city to build one in the US, but France has a few. 

    Here at Point C, we feel that alternative solutions like the diverging diamond interchange and the continuous flow intersection, a close cousin, are exactly what we should be looking into to keep costs down but still find effective, sustainable solutions to congestion, environmental impact, and safety.