‘Shared-space’ streets cross the Atlantic
Up and down the West Coast and in parts of the East Coast, a select group of streets is going through a radical makeover. The street surfaces are being raised to the same level as the sidewalks. Curbs are being eliminated. Trees and vegetation are extending into what had been the domain of the automobile.
Motorists and pedestrians are being expected to use — imagine this! — their intelligence and their powers of observation to operate safely in multipurpose environments. A fundamental premise of modern traffic engineering — that safety can be assured only by strictly separating pedestrians from moving vehicles and by explicitly telling drivers what to do — is under challenge.
The new approach, called “shared space,” is showing up in Seattle, Portland (Oregon), San Francisco, Santa Monica, and other cities on the West Coast; in Cambridge, Massachusetts, New York City, and other places in the East; and in scattered places in between, such as New Town at St. Charles, Missouri, and the South Main development in Buena Vista, Colorado.
A few examples:
• In September the City Council of Santa Monica, California, authorized Nelson\Nygaard Consulting Associates to help implement the shared-space concept on three blocks of Longfellow Street — a residential street near heavily traveled Lincoln Boulevard — and on three streets that connect with Longfellow.
For a long time, the entire 40-foot right-of-way of Longfellow Street was paved with asphalt for cars to drive on and park on, although occasionally pedestrians walked in its center, since there were no sidewalks. This year and last, Jessica ter Schure and Michael King of Nelson\Nygaard worked with a design team including Blackbird Architects, Van Atta Associates, and Sherwood Design Engineers and with neighbors and the city to determine how to convert Longfellow into what Santa Monica planners call a “living street” — a pleasing, landscaped corridor where pedestrians can comfortably coexist with motorists.
Vehicular movement will occupy a single 14-foot-wide lane in the street’s center; when vehicles approach each other, one of them will have to yield. To the sides of the asphalt-paved central travel lane will be on-street parallel parking, most likely surfaced with decorative, permeable concrete pavers to let rainwater seep into the ground. Beyond those will be 5-foot-wide gardens with trees and native, drought-tolerant grasses and shrubs.
Integrally colored concrete with a decorative pattern will probably extend across intersections, to make the pedestrian character of the street readily apparent. The expectation is that motorists will sense that they’re in a mixed environment, and will drive slowly, watching for people in the street. It’s hoped that Longfellow redesign will lead Santa Monica to install more shared streets in the future.
• In San Francisco, Winslow Architecture designed alterations for Linden Street, a narrow passage in the Hayes Valley neighborhood. Architect David Winslow, with financial support from developer Loring Sagan and agreement from the city, proposed repaving the narrow roadbed in patterned, colored concrete, level with the sidewalks. Planters and recycled curb stones, set vertically, will differentiate the travel surface from areas where people can gather and relax.
The objective, says Winslow, is “a landscaped community gathering space where pedestrians and bicyclists will be on equal footing with motorists.” Planted areas, including five trees, will anchor seating areas. “It will be a living room in the street,” Winslow predicts.
• Winthrop Street in Cambridge’s Harvard Square was converted into a shared-space street offering improved access for the disabled as well as a more sociable atmosphere. The walking and driving surfaces of Winthrop Street have become curb-free, covered in a combination of concrete pavers, asphalt, and brick. Previously the sidewalks were too narrow, so people frequently walked in the street anyway — encouraged by relatively slow traffic speeds. Now they can do so more comfortably, by design. Winthrop has several restaurants with outdoor seating, whose activity will naturally overflow into the street.
• Peter Swift at Swift and Associates has designed a woonerf — a paved area shared by people and vehicles — for the South Main development in Colorado. When the woonerf is constructed, possibly next year, buildings will extend over the street at either end. This recalls the Fulton Grove Townhouses in San Francisco, built in 1993 to a design by architect Dan Solomon. In that project, openings in new buildings at the ends of a private street allow vehicles to enter — and create the sense that the motorists are entering a passage where pedestrians have priority. One of the keys to shared-street design is providing visible and sensory cues so that motorists will slow down and pay close attention to how people are using the space.
The European contribution
The father of today’s shared-space movement was the Dutch traffic engineer Hans Monderman, who succumbed to cancer last January at 62. Monderman devoted much of his career to removing traffic signs, signals, markings, bollards, and barriers from small communities in Holland; he accentuated the physical cues that cause motorists to proceed carefully through streets that serve purposes broader than vehicular movement.
Monderman recognized that at an appropriate speed, drivers and pedestrians are able to establish eye contact and anticipate each other’s behavior. They use their intuition. In many locales, the Monderman strategy has been shown to reduce accidents and injuries.
Initially, it was believed that the shared-space approach was appropriate only in small communities and those with low traffic volumes. But as the British traffic and urban design consultant Ben Hamilton-Baillie points out in an impressively comprehensive article — “Shared Space: Reconciling People, Places and Traffic,” in Vol. 34, No. 2, of the journal Built Environment — more recent experience has shown that shared-space principles can work in places traversed by 20,000 or more vehicles per day. In West London, shared-space ideas have been successfully applied to Kensington High Street in the Borough of Kensington despite its stream of more than 40,000 vehicles a day.
Hamilton-Baillie, whose firm Hamilton-Baillie Associates is based in Bristol, England, says the shared-space concept is now well established in Scandinavia and some other places in Europe. Among the communities in England that employ it is Poundbury, the development that Leon Krier designed for Prince Charles.
In the US, much of the experimentation with shared-space design is occurring on alleys and in other streets with very light vehicular traffic. “Intimate streets are a good place to start,” says Winslow in San Francisco. “It’s an easy sell. They’re a natural refuge.”
To make a shared-space street function effectively, designers often use a variety of paving materials and textures, with differing tones or colors — making the place register on the consciousness of motorists. The distinctiveness of the street and the surroundings causes drivers to proceed more cautiously.
Elimination of curbs works to the advantage of disabled people; an obstacle is gone. The blind and visually impaired, on the other hand, sometimes resist the removal of curbs and other demarcations between the vehicular and the pedestrian way. These warn the blind that they may be entering dangerous territory. Textured paving can help to alert the blind to the vehicular portion of a street. Planters or bollards may also act as something of a guide, but if placed too far apart their effectiveness diminishes.
Patrick Siegman of Nelson\Nygaard argues that in the US, mixing of pedestrians and vehicles is less novel than many take it to be. “Most large parking lots — for example, those at shopping centers and grocery stores — effectively function in ways that are very similar to shared spaces on European shopping streets,” he observes. Siegman suggests that Americans have been operating in shared spaces — if drab ones — for decades, without being aware of it.
Perhaps, then, the shift to shared-space streets will be less of a shock than the skeptics think.