First Developments of Different Roundabout Types

Abstract

In the years from 1913 to 1914, Hellier suggested circular traffic systems at places, where several main roads would meet and the main connection of the circular system would prevent overload. At the conference of the local governmental committee on the subject of main roads in 1914, this idea was accepted as positive under the condition that the traffic requirements were met (every intersection should have sufficient empty space, and lawns alongside the intersections would be desirable). The initial phase of development in Europe was interrupted by the First World War. When the British Road Transport Board was set up in 1918, it was suggested that the roads of France should be the model for Europe. Gyratory systems were also used in the USA but there was great difficulty in regulating traffic, local ordinances were unenforceable and flouted, and there was no uniform rule of the road throughout the country. In 1924, at a US national conference, rights of way at intersections, and warning and stop signs were proposed. The “circus” idea continued to spread in the United Kingdom and was frequently recommended for busy junctions of more than four roads. During 1925-26 a lot of gyratory systems were introduced in London. These were simply one-way systems around existing squares with fairly sharp corners. Unfortunately some of the important principles implied in Henard’s concept, e.g. the entries into gaps during circling, operating over a short distance, were being lost. The transfer of these movements to a straight road caused differences in speeds at the conflict points but this may at first have been unimportant when all traffic speeds were quite low. The design was based solely on commonsense and experience [1].