看看老帖:
http://bbs.comefromchina.com/forum5/thread959209.html
http://bbs.comefromchina.com/forum5/thread997386.html
欧洲国家,特别是英国,roundabouts很多。
And Roundabout Rules of the Road from Transport Canada:
http://www.tc.gc.ca/eng/roadsafety/tp-tp15085-1203.htm
http://www.tc.gc.ca/eng/roadsafety/tp-tp14787-menu-179.htm