Because there are no market signals that could identify the best and highest use of street space, it is the role of urban planners to allocate the use of street space between different users and to design boundaries between them where needed.
This article appeared originally in Caos Planejadoand is reprinted here with the publisher’s permission.
As a city expands, planners and surveyors divide its area between private lots and public spaces. Architects, hired by the owners of private lots, design the buildings erected on each one. Lot owners’ taste, budget, and practical considerations shape the design of private buildings. However, land use regulations might restrict the use and shape of the final construction. Over time, changes in consumer demand, building technology, and land prices will require modifications or even the demolition of the original building, which will be replaced by a new one that responds better to current conditions.
This constant land recycling of private lots is a feature of market economies and the motor of urban land use efficiency. Unfortunately, current land use regulations, particularly zoning, tend to slow down this Schumpeterian creative destruction. A paper written by William Easterly, a professor at New York University, monitored the land use change on a Manhattan street over four centuries. The paper shows the unpredictability and necessity of constant land use changes in private urban lots.
In contrast with private lots, public spaces, which include the area occupied by streets, parks, and natural protected areas like beaches, riverbanks, and lakes, rarely change; they are not exposed to market price signals. So, when a city expands, how are the streets designed, and by whom?
On the American continent, little remains of pre-Columbian urban street design. The European colonists’ first task when creating a new town was to separate private lots from public spaces reserved for streets and plazas. Many of these original designs survive to this day. As cities expanded, private developers or municipalities created new roads.
Once fixed by the original surveyors, the city’s roads’ dimensions and patterns seldom change. Consider the design of streets in Manhattan, a borough well known for constantly demolishing and rebuilding ever-taller structures. The pattern and width of streets in the downtown Wall Street area remain identical to what they were at the time of the early seventeenth-century Dutch colony. Even the name, Wall Street, has not changed. The introduction of new, wide avenues, carved by Baron Haussman out of Paris’s medieval districts, is one of the few exceptions to the overwhelming endurance of existing street patterns. Most streets in our cities are fossils dating from the time when surveyors designed the neighborhoods.
Once they have been created, we must accept that streets’ widths and patterns are practically permanent. The areas of streets being fixed, their use has to be rationed. Because supply is inelastic, demand must be managed.
The primary purpose of streets is to allow the movement of people and goods between private lots. But in a large city, there are many ways of moving. Pedestrians, bicycles, scooters, buses, motorcycles, private cars, and cars for hire all contend for the same space. Street space could also be planted with trees. In addition, streets must have room for streetlights, electricity and telecommunication cables, and street and circulation signs. People also use the streets to rest, walk, and exercise. All these conflicting uses occupy precious space that cannot be expanded.
Because there are no market signals that could identify the best and highest use of street space, it is the role of urban planners to allocate the use of street space between different users and to design boundaries between them where needed.
With few exceptions, urban planners have neglected this critical design and regulating role. For instance, on New York City streets, more than two-thirds of the curb space is allocated for permanent parking free of charge. This neglect in the design and regulation of street space contrasts with the complex regulations that planners have applied to private lots. It is time for urban planners to switch their regulatory and design preoccupation away from private lot users and to concentrate on the design and regulation of the scarce space occupied by streets.
The use of private lots should be driven by consumer demand. Land use should emerge from a grassroot process creating an emerging order. By contrast, public spaces are not submitted to price signals that can make their use adapt to evolving demand. The separation of public space between different users is therefore by necessity a top-down design process under the entire responsibility of urban planners.