Clarence Stein

Clarence Stein (1882-1975) was an American architect and urban planner who was profoundly influenced by the Garden City ideals of Ebenezer Howard. In 1929 Stein and Henry Wright developed a new community at Radburn, New Jersey, based on the then-radical principle of separation of pedestrian and vehicular traffic, with discrete networks of motor roads and pedestrian footpaths, separated where possible at crossing points by over- and underpasses. The 'Radburn principle', and Stein's further development of the 'superblock' in his development at Sunnyside Gardens in New York City, contributed greatly to Clarence Perry's notion of the neighborhood unit in urban planning - in effect, a cellular development of towns as agglomerations of smaller, village-type units.

In the United Kingdom Stein's theories were adapted to preexisting urban neighbourhoods by the Metropolitan Police Assistant Commissioner Sir Alker Tripp (1883-1954), who in 1942 advocated the development of a hierarchy of roads and the creation of traffic precincts - city zones where through traffic would be discouraged by the selective blocking of streets.