Construction began in 2006. Design and construction were complicated and at times exasperating—there were five entities involved: Friends of the High Line, the city’s Economic Development Corporation, the Department of City Planning, the Parks Department and the mayor’s office. Switkin recalls:

All of those groups had representatives who you would meet with on a regular basis.  On the one hand it helped expedite certain things through the city process, but on the other hand, it meant that you had to work with five different agencies that had very different priorities.

The need for multiple sign-offs was cumbersome. For example, at one point the designers argued for a waiver from an 18-inch width requirement for park benches in order to install 12-inch-wide seating more in keeping with the park’s aesthetic. They made their point, but only after a time-consuming campaign. Says Switkin:

We must have had every commissioner in the city sit on the bench to figure out if it was comfortable. You had to sort of bring them along, but in the end they were actually very supportive.

In 2009, the city and Friends of the Highline signed a formal public-private agreement. ^[20] The city became owner of the viaduct and invested in the infrastructure of the three-phase restoration and conversion. The resulting public park would become part of the city Parks system. But rather than add to the department’s chronic maintenance shortfall, Friends of the High Line would operate and manage the park. Under the formal licensing agreement, Friends of the High Line would provide about 90 percent of the park’s annual operating budget. It would also contribute to construction costs. Friends of the High Line would be responsible for day-to-day operations and maintenance of the park, and the city would maintain the underlying viaduct. The notion “that it could create value in an underutilized place in the city was what got everybody on board,” says Switkin.

The first of the High Line’s three half-mile sections opened in 2009 and the second section in 2011. The first two sections of the park cost $152.3 million, of which the city provided $112.2 million, the federal government $20 million and New York State $400,000. ^[21] The park’s annual operating budget averaged around $3 million a year. ^[22] In 2011, Friends of the High Line brought in about $30 million and spent about $20 million, much of that for construction. Construction of the third and final section began in 2012 and was projected to cost $90 million, toward which the city committed $10 million. ^[23] By 2013, the city’s analysis put the cumulative economic benefit of the park at close to a billion dollars, well over the roughly $200 million HR&A had originally projected. Overall, both city and nonprofit were satisfied.

The High Line attracted interest from other cities, both in the US and abroad, hoping to repurpose disused or outmoded infrastructure. Its mix of innovative design, public place-making, and real estate development looked to many like urban alchemy. Switkin explains: “Many different people… are looking at the High Line as a model and a precedent for many reasons, whether it’s literally converting transportation methods to something green or to look at the model of the public/private partnership.”

Lisa Switkin: video.

Alschuler argues that the key to creating new parks like the High Line or Brooklyn Bridge Park, which he also worked on, is community involvement:

The most important partnership here is between engaged and passionate citizens and their government. These partnerships are economic. They’re legal. They’re civic. They are ways for the passion of citizens to be engaged in the democracy that reflects their values.

John Alschuler: video.

The High Line did boost an ongoing real estate boom. For some, that was a negative. The pace, scale and price range of much of the development adjacent to the High Line raised questions about equity and influence in city planning. ^[24] High Line advisor and board member Alschuler, however, remains more sanguine:

Has West Chelsea gotten wealthier? Yes. Has the role of the High Line been to exacerbate those trends? No doubt, but this is New York. One of the great things about New York is, we all coexist as part of a diverse neighborhood. It’s one of the reasons why public housing is so essential, [so] that when neighborhoods such as West Chelsea do transition, there are important blocks of housing that will be perpetually devoted to low- and moderate-income people and their future in a diverse neighborhood.

But not all the city’s public-private park projects were equally popular.