by Robert White of Stafford Springs, CT

visits since 041223; last updated 041223

        The history of circular intersections goes back over 100 years.
        See this page on "Roundabout Basics" http://members.cox.net/near/RoundaboutBasics.htm & the link on the Maryland DOT web site on history: http://www.sha.state.md.us/safety/oots/roundabouts/history.asp
        From about 1930 to 1960 hundreds of circular intersections, often called "Rotaries", were build in New England on the principal that "since entering traffic has the right of way, the bigger the circle, the greater the capacity". This has resulted in 100-foot-diameter circles in low traffic areas like Pepperell, & 1,000-foot circles in high-traffic areas like Revere.

        The notion that entering traffic should have the right of way was discredited in the 1960s in the UK, when many rotaries were experiencing total gridlock. When the rule was reversed, so "traffic in the circle had the right of way", two things immediately became apparent:
(1) grid-lock was eliminated, and
(2) the circles no longer had to be large to accommodate heavy traffic (queuing, if any, was now shifted from inside the circle to the entering legs).

        Smaller circles were cheaper to build, as less land and paving material was needed. Then, miracle of miracles, it was noticed that the smaller circle forced vehicles to travel slower. (Although you can drive 45 mph around a large rotary, in a 100-120-foot circle it's hard to exceed 20 mph.) This led to substantial reductions in crashes and in severity of crashes. Also (surprising to many), it allowed more vehicles to pass through the intersection, as drivers found it easier to enter the circles at the much lower speeds.

        Smaller circles result in reduced delays (hence reduced pollution), speeds, crash rates, and personal injuries.
        Since Massachusetts and New York each have over 100 of these large, outmoded rotaries, what is one to do with them? About twenty years ago, MassHighway embarked on a program to replace the rotaries with signalized intersections. Thus we somewhat correctly find articles in the Boston Globe making jokes about rotaries, and saying MassHighway is "getting rid of them all."
        It has also become apparent in these twenty years, that the number & severity of crashes has increased. People are getting killed. In the 1990's, communities started to build the UK-style "modern roundabouts", and by 2000 the Federal Highway Administration (FHWA) became interested in recommending them (see "Roundabouts - An Information Guide"  http://www.tfhrc.gov/safety/00068.htm).
         Insurance Institute for Highway Safety has come out with several papers showing the advantages of roundabouts over rotaries, stop-ed, & signalized intersections (http://www.hwysafety.org/safety_facts/roundabouts.htm).

        There are several reasons why drivers appear to have trouble with the "classic" rotaries in Massachusetts and elsewhere: Lack of uniformity of signs and lines, and lack of training. Until FHWA & MUTCD took an interest in roundabouts, there was no central authority to promote a uniform way of posting signs and painting lines. In some areas, every circle is different!
        The Driver Training Manuals of New England have done little to promote knowledge of even the simplest situations at circular intersections. For stop-ed & signalized intersections, the manuals have several diagrams and the sign section shows many typical signs found near stop lights; however, seldom do these same manuals address circular intersections except to state the rule, "Traffic in the circle has the right of way."
        We can't expect people to be mind-readers!

        So today we are turning a corner, and finding engineers & planners becoming increasingly interested in "making the best" of rotaries by trying to apply the FHWA/MUTCD standards to rotaries without changing the curbing/roadway. As much as 50% improvement of the functioning of rotaries can be expected from the example of the Latham Circle, in NY. In Spring 2005 we hope to see the Greenfield Circle (an Interchange on I-91) retrofitted to FHWA/MUTCD standards. Before-and-after studies are being conducted to document the changes in performance there.
        In Kingston, NY a Rotary was rebuild as a modern roundabout. In Worcester, plans were unveilded to replace Washington Square with a roundabout, but now the city fathers are looking at the advantages of retrofitting the circle.
        Planning & design work on modern roundabouts is proceeding in all the New England states as well as New York, Ontario, Quebec, New Brunswick, & Nova Scotia. 

        Many developers are recognizing the aesthetic and safety benefits of roundabouts, and have been putting them into new developments. New York DOT is moving toward requiring that engineers prove a roundabout will NOT work at a site, before any other design will be considered.
        Attacking roundabouts to try to stop or delay a development cannot be as effective as having the best, most enlightened "Plans of Conservation & Development" and Building & Zoning Regulations in place.
         Roundabouts are simply safe & efficient.  Even where grade separation is necessary due to heavy traffic, using a roundabout to manage traffic on the entrance/exit ramps is very elegant & effective!

         NorthEast Area Roundabouts works on many levels throughout southern New England to promote the advantages of circular intersections. We can arrange informational presentations & workshops of two-hour, half-day, one-day and two-day duration for your company, agency or RPA.

Bob White
North East Area Roundabouts (NEAR)
Roundabout Workshops
Stafford Rotary

Bob White kindly provided this web page in response to my request for information, and it is maintained on my web site with his permission.
--Dick Miller (TheMillers@millermicro.com