Source: adapted from Marshall, W.E. and N.W. Garrick (2010) “Street Network Types and Road Safety”, Urban Design International, 10.1057/udi.2009.31, April 21 2010.
Prior to the late 19th and early 20th century, a grid street pattern was relatively uncommon. The conventional street grid is mostly the outcome of the streetcar suburbs that emerged in the early part of the 20th century. It conferred optimal accessibility and the use of available space. The diffusion of the automobile was a driver in the shift of the street network towards a more curvilinear pattern. This implied a reduction in the level of connectivity as well as the density of land use. This was part of a paradox where while the automobile was becoming the dominant support of urban mobility, it was also increasingly associated with local disturbances. Planners responded by developing cul-de-sac suburban patterns with the goal to reduce and even eliminate through movements on a large number of residential streets and having them taking place on main arterials. By the 1950s, the conventional cul-de-sac pattern became prevalent in suburban developments. Although this pattern minimizes non-local circulation, it also generates more movements and energy consumption.