Imagine Broadway as a pedestrian mall. Vehicles are banned, except for deliveries. Cafes and stores overlook a wide plaza, bisected by a row of trees. There are benches, chairs and tables where people can meet or take a break from shopping. Little kiosks sell coffee or a quick snack. Bicycle parking is plentiful.

A few years ago, anyone suggesting this would have been laughed out of the room. It is almost a rule of nature that New York City streets exist to move as many cars and trucks possible, as quickly as possible, and to provide the maximum number of parking spots.

But the balance is starting to shift. Two key goals of Mayor Michael Bloomberg's PlaNYC 2030are to reduce traffic congestion and increase open space. City agencies, including the Department of Transportation under its new bicycle-riding commissioner, Janette Sadik-Khan, are working intensively to lay the plan's groundwork before the end of the mayor's term.

Streets for People - and Flowers

Against this backdrop, many West Side residents and elected officials believe the time has come to reclaim the streets as public space. In November, several hundred people filled the Jewish Community Center in Manhattan to hear Jan Gehl, the Danish urban planner renowned for humanizing the streets of Copenhagen, London and dozens of other cities. Gehl's talk launched the Upper West Side Streets Renaissance, a campaign to radically reconfigure the streets led by Transportation Alternatives, the Project for Public Spaces and the Open Planning Project.

Gehl is working as a consultant for the transportation department. With a team of volunteers, he conducted studies of how the streets are used in various parts of the city and made recommendations for supporting “walkability” in public life.

He was not free to reveal his suggestions for specific locations, but his vision for the city as a whole inspired the Upper West Side crowd. He said there is plenty of room on New York's broad streets for bus and bicycle lanes, along with wider sidewalks lined with trees as on the boulevards of Paris. Where space allows, there can be flowers, nice benches, good paving stones and public art.

" The nicer a city is, the more you will sit down, not to miss anything," he told a group of reporters on a walk earlier in the day. "New York was made to get from point A to point B. That has changed in many cities. It can change in New York."

Rethinking The Space Between Buildings

The city's minimum open space goal is 1.5 acres per thousand residents. Yet many neighborhoods, particularly low-income minority areas, fail to reach this bar. If current population trends continue, 59 neighborhoods will be deficient in parkland by 2030, according to the projections in PlaNYC.

PlaNYC sets a goal of ensuring that every New Yorker lives within a 10-minute walk of a park. To do that, it proposes re-imagining the entire public realm, not just underused parks and schoolyards but also the public space between buildings, including streets, sidewalks, medians and unused asphalt at oddly shaped intersections.

The plan proposes creating or upgrading a public plaza in every community district and filling in barren blocks with street trees. If this happens, along with reducing traffic congestion, extending greenways and encouraging bicycling, the city could be a much greener place 25 years from now.

Although it would seem that taking away space for automobiles on some streets would clog other nearby roads, research showsthat doesn't happen. Instead, the traffic shrinks. When driving becomes too inconvenient or expensive, people decide to take public transit, carpool, bicycle or walk. In New York City, 90 percent of car commuters have another transit choice.

Creating plazas, adding greenery and making it easier to get around on foot and bicycle offers many environmental, health and social benefits. These changes can also boost property values and business revenue. Studies have found that when safe and appealing public spaces make it easier for people to walk to stores, they spend more time shopping - and more money.

People-friendly streets also help create a sense of community. Studies show that people living on heavily trafficked streets go outside less often and don't allow their children to play in the streets. Gehl believes that urban public gathering places are even more important now than they were in the past. "Today you can easily have a life where you do everything by Internet and driving," he said. "We have found that when we offer bigger public spaces, people come streaming out of their houses to see what's happening."

Taking Back Broadway

Gehl's ideas have particular resonance on the Upper West Side. It is a highly residential area, with a lot of families and senior citizens. Only 10 percent of the residents commute by car, but the high volume of traffic overwhelms the community's streets with noise and pollution and makes it dangerous to navigate on foot or bicycle. Two of the city's great parks - Central and Riverside -- bookend the blocks of apartment buildings and brownstones, but in between there are few public spaces, except for benches on narrow islands of greenery amid Broadway's tumultuous stream of cars and trunks.

Over the next year, the Streets Renaissance campaign intends to bring together planners, elected officials, residents and businesses to create a blueprint to make the Upper West Side into the most walkable, bike-friendly and vibrant neighborhood in the country. To accomplish this, it hopes to introduce traffic calming and safer intersections, encourage bicycle and bus travel, develop a cohesive network of protected bike paths, address the pricing and best use of parking spaces, and reimagine Broadway as a pedestrian way.

An exhibitdisplayed at the campaign's launch suggests some possible changes. A block of 81st Street zigzags around three alternating mini-parks (replacing parking spots), while wider sidewalks at the intersections make crossing safer and add space for plantings, seating and bicycle racks. On Amsterdam Avenue, a tree-filled median separates bicycle and bus lanes from traffic, and curb extensions provide more room to plant trees.

Many ways of reconfiguring the streets would be inexpensive to put in place, requiring mostly a change in policy. For example, on weekends, half the streets could be closed to make playstreets. "You would within a year have a generation of kids growing up meeting their neighbors," said Mark Gorton, founder of the Open Planning Project, who lives on the Upper West Side.

" Basically, every street should be thought of as public space," he said. "A lot of functions that we think of as belonging in parks - it wasn't always that way. Kids used to play in the streets."

One participant in the effort is the Columbus Avenue Business Improvement District, which covers the stretch from 67th to 82nd streets. The business improvement district has been working for more than a year with the Project for Public Spaces to develop a plan for a greener, more inviting streetscape and has prepared a wish list for the Department of Transportation. It includes a physically separated bike lane, expanded sidewalks at the gateway intersections, benches and bike racks. The list also calls for the installation of Muni-meters so that parking can be priced to encourage turnover and make spots available at all times.

The Beginnings of Change

Whatever specific recommendations ultimately come from the Streets Renaissance campaign, there is no guarantee that they will be put in place by the Department of Transportation, which has to weigh competing interests, such as delivery trucks and business owners who want people to be able to park in front of their stores.

Over the past few years, though, the agency has begun making some areas more people-friendly. It has altered streets and intersections to make them safer, and in 2006, it created a very successful temporary public plaza on Willoughby Street in downtown Brooklyn.

These efforts have gained a lot of momentum now that PlaNYC is pushing all the city agencies in the same direction. At the Department of Transportation, Commissioner Sadik-Khan has refocused the staff toward the goals laid out in the plan.

In the last half-year, the agency turneda parking lot in DUMBO into a pocket park and created a public space, a bike lane, and safer pedestrian crossings at the intersection of Ninth Avenue and 14th Street.

To oversee the creation of four new plazas a year, as promised by PlaNYC, the agency hired Andy Wiley-Schwartz, formerly at the Project for Public Spaces, as assistant commissioner in its new Office of Planning and Sustainability. In an e-mail message, Wiley-Schwartz said that the agency is considering sites for new plazas, although none have been selected as yet. "We are especially looking to build plazas in 'underparked' neighborhoods to start, to help fulfill the PlaNYC goal of putting every New Yorker within a 10-minute walk to a park," he said.

At the urging of City Councilmember Gale Brewer, Manhattan Borough President Scott Stringer and the community boards representing the area, the Department of Transportation has also begun a comprehensive study of traffic, parking and pedestrian issues in the Upper West Side.

Given the political clout of automobile commuters and their deep sense of entitlement to drive and park wherever they want, it is still a stretch to think that Broadway could one day resemble a European-style promenade. But clearly, more livable streets are coming to the Upper West Side.

" I think we have a tremendous opportunity to push the envelope," said Paul Steely White, executive director of Transportation Alternatives, "to not just realize some very progressive street changes but also to lock in a whole new paradigm for street management that will continue into the next mayoral administration."

Speaking at the Streets Renaissance event in November, Commissioner Sadik-Khan described a recent trip she and City Planning Commissioner Amanda Burden had taken to Denmark. "To see how safe everyone felt on the streets in Copenhagen really affected me," she said. "I don't see why we can't have some of that here."

The next event scheduled for the Upper West Side Streets Renaissance campaign is a talk on December 10 by Dr. Donald Shoup, author of the "High Cost of Free Parking," on how changes in parking policy can improve the public realm and generate the revenue to do it.

Anne Schwartz, in charge of the parks topic page since its inception in 1999, is a journalist who specializes in environmental issues.