This paper describes a new pattern for the streets in a metropolis.
Average speeds in an area laid out according to this pattern would be 45 mph, ar against the 15 mph typical for urban areas today: yet mean trip length is increased by only 5%.
The principal features of the pattern are: all streets are parallel; there are no cross streets; streets are connected by freeways 3 miles apart
The Geometry …The geometry is shown in diagram form in Figure 1. Its essential features are:
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All streets are parallel. There are no cross streets, and no two streets intersect.
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The streets are about 500 feet apart.
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Streets are one way, alternate streets running in opposite directions.
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At 3 mile intervals multi-lane freeways run under the streets
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Pairs of streets are connected to the freeways by clockwise loops.
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Neither pedestrians nor parked cars are allowed on the streets.
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The strips of land between the streets, where the buildings are, are continuous pedestrian areas.
Access driveways in these areas go all the way from one street to the other, but are interrupted by frequent ridges, so that vehicles cannot move on them at more than walking pace.
Generating Demands Requirements:
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Movement in the city must allow the maximum free use of personal vehicles.
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Average speeds must be as high as possible. Average trip times must be as low as possible.
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The street pattern must connect any two points with roughly equal efficiency.
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The system of streets must be essentially at ground level.
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It must be possible to take long walks from any house; and it must be possible to walk to neighbors’ houses, to borrow things and to get help.
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There must be a smooth transition between streets and freeways.
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Vehicles turning on and off a street must not endanger other high speed traffic on the street.
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Vehicles must be able to get to within a few feet of any building.
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Wherever the pedestrians go, they must be safe from traffic.
…The pattern of parallel streets solves the problem of congestion. As far as I can see, the pattern is causally self-contained and raises no new problems of its own; it is compatible with the other elements of the existing city. But it is not in itself a plan; it is merely a basic scheme. Like the grid pattern, it will have to be modified, transformed, and interrupted, as the need arises.
Finally, let me repeat: It is not necessary to build this pattern from scratch. The essential features of the pattern can be obtained in most existing cities gradually, by closing cross streets, one at a time.
[Commentary: ’…No cities followed this advice, to our knowledge, but the paper was influential because it introduced the concept of creating novel patterns to solve specific problems. His subsequent work introduced a “pattern language”2, 3, with each of 253 patterns giving the principle of a solution but not the implementation. In Alexander’s words, “each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice.”2.’]