The magic roundabout
The roundabout was constructed according to the design of Frank Blackmore, of the British Transport and Road Research Laboratory. Traffic flow around the inner circle is anticlockwise, and traffic flows in the usual clockwise manner around the five mini-roundabouts on the outer loop.
The complex junction offers multiple paths between feeder roads. The outer circle carries traffic in a clockwise direction, like a normal roundabout (in places where traffic drives on the left hand side of the road), and less proficient users may choose to use only the outer circle. The inner circle carries traffic in an anticlockwise direction, and more proficient users may choose to use the alternative paths.
Use of ephemeral and plastic constraints
When the roundabout complex was first opened, the mini-roundabouts were not permanently marked out and could be reconfigured while the layout was fine tuned. A police officer was stationed at each mini roundabout during this pilot phase to oversee how drivers coped with the unique arrangement.
Once the layout had been tuned, it was fixed. Virtually the same overall configuration has been in place for 48 years.
Experience and results
In 2005, it was voted the worst roundabout in a survey of the general public by a UK insurance company. In September 2007, the Magic Roundabout was named as one of the world's worst junctions by a UK motoring magazine. In December 2007, BBC News reported a survey identifying The Magic Roundabout as one of the "10 Scariest Junctions in the United Kingdom".
However, the roundabout provides a better throughput of traffic than other designs and has an excellent safety record, since traffic moves too slowly to do serious damage in the event of a collision.
In 2010, the National Cooperative Highway Research Program concluded that the roundabout reduces injurious crashes by three quarters.