he mile-and-a-half path of concrete planks will weave among plants and wildflowers like a curvilinear boardwalk meandering through a floating garden. Some entrances will emphasize a gradual ascent from the grit and congestion of the city's streets to an oasis of pastoral calm. The 22-block stretch is to include the unexpected: an adjustable chair that can become a table or a chaise longue; a walkway flanked by a wetland with lily pads.
These details and others have been refined over the last several months by designers who plan to create an elevated public walkway out of the High Line, an abandoned railway that runs 30 feet above the city between 10th and 11th Avenues in Manhattan, from 34th Street to Gansevoort Street in the meatpacking district. The most recent digital drawings and renderings, including a 20-foot-long architectural model, go on display at the Museum of Modern Art tomorrow.
"Landscape architecture and urban design are completely integrated," said the show's curator, Tina di Carlo, an assistant curator in the museum's architecture and design department.
Construction of the project, designed by the New York-based architectural firms Field Operations and Diller, Scofidio & Renfro, in cooperation with the city and the nonprofit group Friends of the High Line, is expected to begin by year's end.
However innovative the design, the ultimate aesthetics and workaday experience of the High Line will hinge on how it relates to its surroundings, which are currently in flux. New construction is planned along the High Line, including several buildings that will intersect the railway. In addition, the Jets stadium and convention center, if built, could have a profound impact on the High Line's views and crowds.
The design team has been focusing on the first phase of the High Line, the southernmost portion, from Gansevoort Street to 15th Street, deciding on elements like seating, security and access. "It's answered a lot of the practical questions we've always had: how do you make it safe, and how do you get up there? At the same time, how do you keep it interesting?" said Robert Hammond, a founder of Friends of the High Line.
The designers are beginning to consider how the High Line will pass through or abut various new buildings, including a 15-story André Balazs hotel designed by Polshek Partnership at 13th Street; a building designed by Robert A. M. Stern between 17th Street and 18th Street, developed by Edison Properties; and a building designed by Frank Gehry, developed by Georgetown Partners between 18th Street and 19th Street.
"Yes, it poses technical and financial burdens on the hotel," Mr. Balazs said. "But I think the goal is to embrace it. As difficult as it is, I think it's really worth the challenge."
Much of the designers' work has been devoted to seeking a balance between preserving what one called "the romance of the ruin" - wild grasses growing up through the metal skeleton of rails and rivets - and creating a fresh green corridor for pedestrians. (The High Line is currently off limits.) "There is an ecosystem in place," said Elizabeth Diller, one of the architects. "The moment you let people up there, that ecosystem will be destroyed. We have to find a way for humans and growth to coexist."
James Corner, the founder and director of Field Operations, the project's landscape architect, described the challenge as "how to maintain the magic of the High Line as a found landscape in the city, yet at the same time accommodate the numbers of people who want to stroll up there." The concrete planking system is to cover about half of the High Line, a soft layer of vegetation the remainder. But these proportions are flexible; planks can be added to reduce the amount of greenery and vice versa.
"We're trying to keep this as uncommercialized as possible," said Ricardo Scofidio, another of the architects, "to keep it simple and natural and not to overwhelm it."
In developing plans for the downtown portion of the High Line, the designers have been focusing on how the walkway will interact with the street, distinguishing among the different entrances in terms of speed - some will provide a slow ascent; others will be more direct. Every access point is to have a presence at ground level.
The one at Gansevoort, for example, is to feature a large glass-encased area that may be used for a restaurant directly underneath the High Line; it will rise gradually to the walkway, so that people come close to the metal bones of the structure as they move up into it. Also at Gansevoort, where the railway begins, the architects plan to leave the existing exposed section of the High Line, "so you can clearly understand the construction of the structure," Mr. Scofidio said.
The design calls for a variety of seating options all along the High Line, including loose chairs and benches - "all sorts of combinations as to how the public could inhabit this space," said Ms. di Carlo, the assistant curator. "A couple or a couple with a baby or disabled people or someone walking their dog," she added, "all of that has been studied."
The designers hope to use the areas of the High Line that are covered by buildings as rental spaces for events to generate revenue. Lighting along the line is to be kept as a soft ambient glow below eye level. The designers expect the area to be monitored by video cameras. The architects plan to keep the original steel railings - "designed to keep locomotives from plunging into the street," Mr. Scofidio said. To meet the code requirements at crosswalks would require the installation of eight-foot walls that would obstruct east-west views. As a result, the architects are planning to add glass or a fine mesh to the railings and to create a wetlands area at 14th Street that will keep people from the edge.
The show opening tomorrow at the Modern features large-format photographs by Joel Sternfeld, a New York photographer who has documented the High Line's current rough, overgrown condition.
The design team also includes Piet Oudolf, a horticulturalist; Olafur Eliasson, an artist; and the firm Buro Happold, structural engineers.
Friends of the High Line, the nonprofit group that successfully fought to save the railway from demolition in 2001, has raised about $3.5 million in private money. The city has committed about $50 million, and support is expected to come from the federal government and the state.
"For a long time, the mystery of the High Line was it could be anything," said Joshua David, a founder of the High Line group. "Now we have a design developing that retains that same sense of mystery and possibility even as we're narrowing down to a singular vision."
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