Shared space applied to high-volume intersection

It’s been nearly a year since a major traffic light was removed at an intersection with 26,000 vehicles per day, heavily used by truck traffic in Poynton, Cheshire, England. A section of the town’s High Street was also renovated so that pedestrians, bicyclists, and vehicles all mix. The volume of vehicles is nearly double the upper limit for “shared space” intersections according to industry standards.

“This was the most ambitious shared space project — certainly in the UK — any anywhere else that I am aware of,” says Ben Hamilton-Baillie, a British urban designer who led the project.

Accidents have gone down so far, although Hamilton-Baillie cautions that it is too early to draw conclusions on safety. Traffic queues have been drastically reduced, despite an increase in pedestrian space of more than 100 percent.

Poynton is on the A523, also called the London Road, connecting Manchester to Stoke-on-Trent. Construction took two years, partly because a primary sewer line collapsed and had to be replaced, which raised costs to 4 million pounds ($6.4 million).

A truck and cars navigate the primary intersection with its two “roundels.” Photos courtesy of Ben Hamilton-Baillie

The number of traffic lanes were significantly reduced — from three to one in the major thoroughfare — and two to one on the high street. Given that peak traffic queues of a half mile frequently occurred prior to reconstruction, many were opposed to the reduction in lanes, Hamilton-Baillie says. Now that the traffic is flowing better than it was before, these skeptics are turning into supporters.

The project has counterintuitively increased capacity, Hamilton-Baillie says. “You get more efficient use of critical central space at low speeds, because drivers are able to anticipate movement and actions of other drivers more efficiently. They do not have to cope with multiple approaches. There are small headways between vehicles. And you get more vehicles through the space.” The elimination of the traffic signals means that there is no waiting time between signals and vehicles are constantly moving.
At the busiest times, now, queues are about 100 meters, or 300 feet. Traffic speeds range from 16 to 18 miles an hour.

The primary intersection has been changed from a large, complex, traffic light to two of what Hamilton-Baillie calls “roundels,” delineated by gray brick pavers, in a figure eight pattern. One roundel is about 90 feet across, with an inscribed circle of 16 feet in the middle (traffic can drive across this circle). The smaller roundel is 64 feet in diameter. The pedestrian space on the outside of the roundels has orange brick and is separated by a low, two-inch curb. The term “roundel” is commonly used to refer to a Royal Air Force insignia — but Hamilton-Baillie applies it for the first time to the shape of an intersection. 

A lot of effort was put into designing approaches, Hamilton-Baillie says. Strong gateways were created to slow down traffic and funnel it into single lanes. Similar care was taken in the multiple pedestrian crossings on the high street. The standard crossings were replaced with different color pavement. The traffic lanes are very narrow on the high street. Trees were planted and there is modest provision for on-street parking. “Poynton is already well supplied with parking,” says Hamilton-Baillie. 

One of many pedestrian crossings on Poynton High Street. Photos courtesy of Ben Hamilton-Baillie

“All of the evidence shows an increase in the pedestrian counts, and anecdotal evidence of an increase in bicycle traffic,” he says. “The retail stores are doing better. The number of vacancies has dropped.”

High streets in Britain are going through a hard time now, he says, and there is a shift toward restaurant uses from general merchandise. “The intent of the plan is to keep the coherence of a town and make the high street more successful while coping with very high volumes of traffic,” he says.

Poynton could be a model, he adds. The maximum of 14,000 vehicles per day for shared space in the literature “is not based on anything solid. It has become established wisdom, and this could shatter the established wisdom,” he says. “I think it will begin to open up wider range of applications for shared space than people have tended to use in the past. How busy are the intersections that these principles can applied to? The honest answer is we don’t know.”