Great Streets by Allan Jacobs: What Makes a Street Great

Great Streets (1993) is the book in which the planner Allan Jacobs, a professor at Berkeley and formerly San Francisco's planning director, answered a question that seems simple and is not: what makes a street great, not by its size but by the life it sustains. To answer it he drew at the same scale and walked dozens of streets around the world, from the Champs-Élysées to Barcelona's Rambla, from the Paseo de Gracia to Rome's Via dei Giubbonari and the tiny Roslyn Place in Pittsburgh, and drew from the comparison the physical qualities they share. His conclusion is that great streets are designed, and that their ingredients are known and reproducible.

The eight requirements of a great street

Jacobs distinguishes between requirements and contributing factors. The requirements are eight. Places for people to walk with some leisure, wide and continuous pavements where people can go at their own pace. Physical comfort: shade in summer, sun in winter, protection from wind. Definition: façades and trees that bound the space and give it proportion, like an outdoor room. Qualities that engage the eye: details, variety, things to look at every few metres. Transparency: doors, windows and shopfronts that connect inside and street. Complementarity between buildings, alike without being identical. Good maintenance. And quality of construction and design.

Trees, proportions and time: the contributing factors

To those requirements he adds contributing factors: trees, which Jacobs considers the most effective element for transforming a mediocre street; clear beginnings and endings, a square or monument that marks where it starts and stops; variety of buildings and uses; accessibility for all; the density of people and activities that sustains it; places to sit and stop; and time, because great streets mature over decades. Jacobs measures each with comparative drawings at the same scale, pavement widths, façade heights, tree spacing, and shows that the ratio of height to width, around one to one or one to two, appears in almost all of them.

Against the car's street: speed, crossings and boulevards

The book is also a critique of twentieth-century street design. Traffic engineering standards sized streets for the car, with wide lanes, generous turning radii and residual pavements, and produced fast, dead roads where nobody wants to be. Jacobs shows that great streets usually carry traffic, the Champs-Élysées does, but the car is subordinate: low speeds, frequent crossings, parking that does not dominate and central space for the pedestrian. In The Boulevard Book (2002), with Elizabeth Macdonald and Yodan Rofé, he extended the analysis to multiway boulevards that engineering considered dangerous and that turned out to be among the safest and liveliest.

The influence of Great Streets on urban design guides

The influence of Great Streets shows in everyday-life urbanism and in the street design guides that cities around the world have adopted since the 1990s, from complete streets manuals in the United States to the public space guides of London or Barcelona. His method, comparing real streets drawn at the same scale, is still taught in architecture schools, and his list of requirements serves to diagnose any street: what it lacks and what should change. Jacobs converses with Jane Jacobs, to whom he is not related, and with Jan Gehl and William Whyte, but his specific contribution is to have translated street life into dimensions.

Allan Jacobs's lesson is that a great street is not a luxury of European capitals but the result of concrete decisions within reach of any city: widen the pavement, plant trees in a line, define the space with continuous façades, open the ground floors, lower the speed and take care of the details. The best streets in the world are, in his analysis, those designed so that people would want to be on them, and that intention remains the only recipe that works.