What Goes Around

The fact that I put $80.08 worth of gas in my car (very large tank) yesterday has me thinking, like everyone else across the planet, about fuel efficiency. You probably already know some of the basics - 55 mph, take 'er easy on the AC (although if the only alternative is rolling down the windows, the added aerodynamic drag can actually make AC the more efficient option).
But it also turns out a great way to tackle aggregate fuel efficiency is the replacement of traffic-lighted intersections with roundabouts (traffic circles). As you recall from your high school physics, accelerating something takes a great deal more force - and therefore more fuel - than maintaining its speed. So a good traffic scheme minimizes braking and acceleration, which is what you have in a roundabout.
This page cites studies that show a roundabout represents about a 30% reduction in emissions (and therefore increased efficiency) compared with the signalized intersection it would replace. It's safer (for motorists and pedestrians) than a signalized intersection as well, because speeds are lower.
This is not to say they are completely without dangers, though:




Postscript. Maybe everyone knows this already, because my googling for this post shows me there was a story about it yesterday on no less than All Things Considered.