Problem
The net-like pattern of streets is obsolete. Congestion is choking cities. Cars can average 60 miles per hour on freeways, but trips across town have an average speed of only 10 to 15 miles per hour.
Solution
Within a local transport area build no intersecting major roads at all; instead, build a system of parallel and alternating one-way roads to carry traffic to the Ring Roads (17). In existing towns, create this structure piecemeal, by gradually making major streets one-way and closing cross streets. Keep parallel roads at least 100 yards apart (to make room for neighborhoods between them) and no more than 300 or 400 yards apart.
Related Patterns
… in earlier patterns, we have proposed that cities should be subdivided into local transport areas, whose roads allow cars to move in and out from the ring roads, but strongly discourage internal movement across the area — Local Transport Areas (11), Ring Roads (17) — and that these transport areas themselves be further subdivided into communities and neighborhoods, with the provision that all major roads are in the boundaries between communities and neighborhoods — Subculture Boundary (13), Neighborhood Boundary (15). Now, what should the arrangement of these roads be like, to help the flow required by Local Transport Areas (11), and to maintain the boundaries?
The parallel roads are the only through roads in a Local Transport Areas (11). For access from the parallel roads to public buildings, house clusters, and individual houses use safe, slow, narrow roads which are not through roads — Looped Local Roads (49), Green Streets (51) — and make their intersections with parallel roads a “T” — T Junctions (50). Keep the pedestrian path system at right angles to the parallel roads, and raised above them where the two must run parallel — Network of Paths and Cars (52), Raised Walk (55). Provide a Road Crossing (54) where paths and roads cross.
Alexander, Christopher. A Pattern Language: Towns, Buildings, Construction. Oxford University Press, 1977, p. 126.