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Roundabouts
in the UK
| The first roundabout
was constructed in Paris around the Arc de Triomphe in 1901. According to the
BBC the first "recognizable modern roundabout" was New York's Columbus Circle.
The first British roundabout was five years later, in Letchworth Garden City in
1909 - originally intended partly as a traffic island for pedestrians. However,
the widespread use of roundabouts began when British engineers re-engineered the
traffic circle in the mid-1960s and Frank Blackmore invented the mini
roundabout to overcome its limitations of capacity and for safety issues.
Unlike traffic circles, roundabouts operate with yield control to give priority
to circulating traffic and eliminate much of the driver confusion associated with
traffic circles and driver wait associated with junctions that have traffic lights.
Roughly the same size as signalled intersections with the same capacity, roundabouts
also are significantly smaller in diameter than traffic circles, separate incoming
and outgoing traffic with pedestrian islands and therefore encourage slower and
safer speeds |
Some of Several UK Roundabout Signs. More Signs information
Click Here
Roundabouts are safer
than both traffic circles and traditional intersections—having 40% fewer vehicle
collisions, 80% fewer injuries and 90% fewer serious injuries and fatalities (according
to a study of a sampling of roundabouts in the United States, compared with the
intersections they replaced). Roundabouts also reduce points of conflict between
pedestrians and motor vehicles and are therefore considered to be safer for them.
However, roundabouts, especially large fast moving ones, are unpopular with some
cyclists. This problem is sometimes handled on larger roundabouts by taking foot
and bicycle traffic through a series of underpasses.
Movement within a
roundabout in a country where traffic drives on the left.
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Mini
roundabouts
Mini-roundabouts exist
at smaller intersections to avoid the use of signals, stop signs or the necessity
to yield in favour of one road of traffic. Mini-roundabouts can be a painted circle,
a low dome, or often are small garden beds. Painted roundabouts and low domes
can easily be driven over by most vehicles, which many motorists will do when
there is no other traffic, but the practice is dangerous if other cars are present.
Mini-roundabouts work in the same way as larger roundabouts in terms of right
of way. They can often come in "chains", making navigation of otherwise awkward
junctions easier. There are usually different road signs used to distinguish mini
roundabouts from larger ones.
In the UK the maximum diameter permissible of a mini-roundabout is 4m. Whilst
it may be physically possible, it is illegal for vehicles like cars, which can
turn around the mini-roundabout, to go over the painted island, or around the
wrong way- vehicles should treat it like a solid island and proceed around it.
(In practice, few motorists obey these rules). Some local authorities have installed
double white lines around the island to indicate this, but these are not permissible.
The centre island also must be able to be over-run by larger vehicles. If this
is not possible, perhaps due to plants, or street furniture it is considered a
small roundabout not a mini roundabout and as such must adhere to the stricter
roundabout guidelines
A slightly larger version of a mini-roundabout, sometimes called a "small roundabout",
is designed with a raised centre surrounded by a sloped "overrun area" of a different
colour from the roadway and up to a meter in thickness called a "truck apron"
or a "mountable apron". The truck apron's design discourages small vehicles from
taking a shortcut over it while at the same time allowing the mini-roundabout
to more easily accommodate the turning radius of larger vehicles (such as a truck
which may have to navigate the roundabout). These are not well suited for bus
routes, as mounting the apron can be somewhat uncomfortable to passengers.
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