Roundabouts: Good for What Ails You

An alert reader sent us this literature review page from WSDOT, touting the benefits of roundabouts:

  • 37 percent reduction in overall collisions
  • 75 percent reduction in injury collisions
  • 90 percent reduction in fatality collisions
  • 40 percent reduction in pedestrian collisions

9 responses to “Roundabouts: Good for What Ails You”

  1. So, an idea that I’ve been trying on for size is to begin replacing traffic signals with roundabouts within our existing cities, as a part of a program to broaden the modal choice on arterials through cycle track installation and slimming down of mixed-flow lanes to one in each direction… Obviously, there would be huge safety benefits from doing so, not to mention positive traffic-calming effects. The question in my mind is whether this could also lead to an overall reduction in VMT; that is, if congestion might be lessened through trip avoidance as a net positive side effect?

  2. I’m a roundabout fan who needs to acknowledge that their safety record for cyclists has been mixed. The newer ones seem to be better designed for bicycles, but the multi-lane instances remain a concern.

  3. Scotty, I like the way you think :)

    As for the bike issue, here’s an example of a cycle-friendly roundabout.

    Visiting Astoria a couple of days ago, I was reminded of all the advantages of roundabouts when driving through the formerly gnarly intersection of US 101 and OR 202 (unless I’m mistaken this was the first true roundabout to be built in Oregon). The only real disadvantage to roundabouts that I can see is their larger footprint, but the increased safety and decreased congestion more than mitigate this.

  4. Thanks, dan, I always try to be progressive.


    I’m assuming by “true roundabout” you mean what traffic engineers call a “modern roundabout“, which has specific design criteria. Such criteria serve to exclude many older pre-existing traffic circles, such as NE Chavez (39th) and Glisan (stop-signs control entry into the circle) and the former circle at SW Barbur and Terwilliger (signal-controlled, with through traffic on Barbur not needing to enter the roundabout, whereas traffic turning left on to Terwilliger did).

  5. I come from the UK, a country that never met a traffic problem it didn’t think it could solve with a roundabout, and I hope to never see one again. They’re a horribly suburban solution, that take up a pretty large amount of land compared with signalled intersections. This is (arguably) fine in the exurbs; but unacceptable in the city. Just try to imagine Portland’s Central City if roundabouts were widespread. It would be horrible for walking and cycling. Not a direction we should desire to move in.

  6. I’ve wondered about the real estate issues myself… And the effects on pedestrian access. It is true that a pedestrian attempting to cross a single street will experience benefits of visibility, safety, and drivers stopping sooner, when utilizing a roundabout. But when crossing two streets, isn’t the walk necessarily further? Imagine if very-walkable NW Portland (21st/23rd) were configured primarily as roundabouts, and pedestrians had to divert 25-50ft at every intersection in order to continue along the corridor?

    Is there a happy medium?

  7. I wouldn’t put a roundabout at every intersection on NW 23rd, but one was considered at 23rd/Burnside as part of the West Burnside plan.

    I suspect it would have performed well, but alas it would have required taking a large amount of private property (possibly including some buildings).

  8. 39th and Glisan needs to have the stop signs removed, and needs bike improvements. I am okay taking the lane, but a lot of cyclists are not.

    We have several mini-roundabouts in our neighborhoods which are controlled by stop signs in one direction. These never made sense to me…

    NE 37th and Prescott would be a good candidate for a roundabout. This intersection is very dangerous for north/south traffic on 37th due to the blind corners and high speeds on Prescott. I would like to see more of these placed strategically for traffic calming.

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