It is common for people to use the terms roundabout and traffic circle interchangeably, as though there is no difference between the two. Sadly, Streetsblog San Francisco, whose mission is to educate the public, claims that there is no significant difference and that it is OK to use the terms interchangeably (SFMTA Launches “Muni Backwards” […]

Continued from Part 1 Streets should be designed to induce traffic speeds that are appropriate to that street, consistent with surrounding uses. In my mind, that means 20 mph in residential areas and up to 30 mph in commercial areas. What about all those other roadways? They are mis-designed stroads. Properly designed streets: have a […]

I have noticed a lot of confusion in Sacramento amongst both transportation professionals and citizens interested in traffic calming about roundabouts. If you live, work or play in downtown and midtown Sacramento, you’ve seen a lot of structures in the intersections which people call roundabouts, but which are not, they are traffic circles. So what is a roundabout?

intersection conflict points

intersection conflict points

A modern roundabout is a structure that allows a free flow of traffic without stop signs. Instead, they use yield signs and markings. They are most appropriately used at street intersections where both streets are fairly busy. The biggest advantage of a roundabout, for all users, is the reduction of conflict points in the intersection from thirty-two to four, as illustrated in the diagram at right!

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