WRITTEN IN SUPPORT OF ROUNDABOUTS
history of circular intersections goes back over 100 years.
by Robert White of Stafford Springs, CT
visits since 041223;
last updated 041223
page on "Roundabout Basics"
http://members.cox.net/near/RoundaboutBasics.htm & the link on
the Maryland DOT web site on history:
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.
that entering traffic should have the right of way was discredited in
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
(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).
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
a large rotary, in a 100-120-foot circle it's hard to exceed 20 mph.)
to substantial reductions in crashes and in severity of crashes. Also
(surprising to many), it allowed more vehicles to pass through the
as drivers found it easier to enter the circles at the much lower
circles result in reduced delays (hence reduced pollution), speeds,
crash rates, and personal injuries.
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
intersections. Thus we somewhat correctly find articles in the
Boston Globe making jokes about rotaries, and saying MassHighway is
"getting rid of them all."
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"
Insurance Institute for Highway
Safety has come out with several papers showing the advantages of roundabouts over rotaries, stop-ed, & signalized intersections
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!
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."
expect people to be mind-readers!
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
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
& design work on modern roundabouts is proceeding in all the New
England states as well as New York, Ontario, Quebec, New Brunswick, & Nova
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.
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 &
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 kindly provided this web page in response
to my request for information, and it is maintained on my web site with