Our friends said it was put in for the new shopping mall and a big subdivision that connects into the intersection on the west. The waits at the intersection would have been too long for the shoppers and the new homes, without changing the intersection. The roundabout worked great. Traffic smoothly transitioned into and out the intersection with only mild acceleration/deceleration. Rarely did you have to stop, but when there were bursts of traffic people did have to stop and wait to go against the dominant flow (myth busted: no stopping with roundabouts). The radius seemed larger than ones in Encinitas. For an intersection with light traffic and with people frequently turning down any of the exits, the round about was the clear winner.
As for being the best for CO2 emissions, roundabouts can not logically be the universal best solution (but, so what, a lot of public policy is based on vehicle miles traveled, not CO2 emitted. Did you know that?). As for the problem of slowing down emergency response, the response looks like it will be hit with only a small new delay when going only one of the four directions. If there were ten roundabouts in a row, and especially if they all had really small radii, that might sum to a delay that shouldn't be dismissed.
I got the following link in my in box while I was on Kauai.
USA Today: Fire Departments and New Urbanies at Odds
Urban villages, quaint and pedestrian-friendly developments embraced by environmentalists, are sparking opposition from fire officials who say the streets are too narrow for their fire engines.
The popularity of such residential complexes sprouting throughout suburbia is forcing a rethinking of street design so the villages can accommodate both emergency responders and a desire for more intimate neighborhoods...
[I've never understood the hope that we will get a small town social dynamic by becoming embedded in a bigger social network. I've never seen the claim backed by data either. Anyone seen it?]
"It's far different than it was 10 years ago because people have actually started talking," says Jim Tidwell, a former chief of the Fort Worth Fire Department and a member of the city's planning commission. "Let's try to find a solution."
U.S. guidelines set by the International Code Council call for 20-foot-wide streets, but individual communities can adopt the codes and regulations they want. Some require 24-foot widths.
In sprawling suburbs where fire stations serve a vast area, departments opt for large trucks that can respond to a variety of calls. Because many suburban subdivisions are closed off by cul-de-sacs and have only one way in and out, firetrucks need wide streets to get their apparatus in and out.
Groups such as the Congress for New Urbanism, a non-profit that promotes the health and environmental benefits of walkable neighborhoods, are turning up the pressure to come up with guidelines that can accommodate urban villages without jeopardizing fire safety.[Moonlight lofts was smart growth/new urbanism. It didn't appear that anyone walked for utility trips or didn't use their auto as a primary means of transport among inhabitants of moonlight lofts. Then there is, Billions have been spent on transit-friendly housing, but it appears people aren't leaving their cars behind.]
"As our streets grew and as our budgets grew, our equipment grew," says Charles Marohn, a Minnesota engineer and one of the founders of the Strong Towns blog, which comments on the financial implications of development. "As cities are forced to contract, we're finding we can't afford the system we've created."
Proponents of narrower streets say they reduce car and pedestrian accidents because traffic slows when streets are not as wide.[Curved and narrow streets doesn't seem to solve the speeding/safety concerns in Cardiff.]
•One of the techniques for creating narrow, calm roadways and still provide emergency access are drivable sidewalks and roll-down curbs, Tidwell says.
"It restricts normal traffic to the width of a lane," he says, but wider vehicles can straddle sidewalks.[The Encinitas FD had spoken publicly about roundabouts having a negative impact on response time. I don't know that there has been an official or justified reversal of their conclusions. Anyone know if they include roundabouts in their response time modeling?]