Grand central viewing station

As part of creating a bespoke structure in the centre of a major New York development to offer unique public space, Heatherwick Studio utilised a revolutionary technique to create a copper finish in steel that wouldn’t degrade over time, as Roseanne Field reports

The neighbourhood of Chelsea on the west side of Manhattan, New York, is home to a huge new development – Hudson Yards. Dubbed the “cultural centre” of Manhattan’s New West Side, the project by real estate companies Related and Oxford Properties Group consists of offices, public art and cultural institutions, a hotel, over 100 shops and restaurants, 14 acres of public space, and four residential towers with apartments for both sale and rent. What Related felt the development was missing was something at the heart to tie it all together, and so they approached a range of practices to come up with a concept. Heatherwick Studio had the winning submission, and the project moved forward from there in what was a “quite straightforward” process, says project leader at the firm Laurence Dudeney. The practice more or less had free reign. “It was kind of a great blank slate in a way,” Dudeney explains. “They put so much work into this mega development, really historic in terms of its size and quantity and funding, but they knew they needed something to really bind it all together.” The development had been designed “really smartly,” he says, to provide a piece of open, public space. He adds: “They were engaging with us on how to activate it and give prominence to the whole development.” Originally, the project’s landscape architects, Nelson Byrd Waltz, had come up with designs for the plaza but, says Dudeney, “they realised that they needed something more”.

Design development

Having been given a relatively open brief, Dudeney and the team’s first thought was that whatever they designed needed “a single point of focus” and “to have some ability to hold its own” and therefore draw people to it. “Our main concern was that this development was so big and whatever we put in there would just get lost,” he explains. Their original line of thinking was looking at sculptures – “it’s not uncommon in New York for a developer to think about putting in a piece of public art,” explains Dudeney – but it was an idea they quickly dispelled on the basis people would simply take pictures and walk away. “We wanted something much more engaging and interactive,” he says. They looked at various ways of doing this – such as with digital and mechanical interventions – but ultimately agreed it needed to be “more open” and a public space that “you should be able to walk into and experience. It was the idea of allowing people to experience public space from a different dimension,” he explains. They decided to build a tall structure for a couple of key reasons. Firstly, it seemed logical in that it would create more space than what was there already, as opposed to constructing something that would take away that space. It was also for this reason that Vessel takes its unique shape, increasing in width the higher its gets. “Rather than reducing the space left for the city, we wanted to raise it and bring people up,” Dudeney explains.

They also wanted to keep the structure in proportion to the heights of the surrounding buildings. “It needed to have a decent scale in order to do it justice,” says Dudeney. The site itself, and specifically the High Line – a 1.45 mile- long raised park, ‘greenway’ and rail line on New York’s west side – also influenced their thinking. “It’s really energised people and made them think about New York in a different way by making it accessible.” The piece of “heavy infrastructure” inspired them to “think about infrastructure as a way of expression”. The entire development has been constructed on a platform over  working train lines with trains constantly running underneath, explains Dudeney. “It’s a phenomenal achievement. It’s so New York, it’s just another layer,” he says. “That kind of American ‘look forward’ mentality, we were excited by how infrastructure could play a part in this.” Coming up with the unusual shape wasn’t something that took the team too long. “This was an almost immediate understanding,” explains Dudeney. They had spent time researching public spaces around the world, particularly in Europe, and realised that areas with a change in level – such as the Spanish Steps in Rome – were a “phenomenal magnet for people to come and hang out.” They began exploring the idea of using steps and “went on this exploration of stairs and historic infrastructural uses of them”. At this point they came across the Indian Stepwells, the geometry of which became the direct inspiration for Vessel’s design. “We were thinking about how the geometry would play and fit,” says Dudeney. “But the idea always remained the same.” The resulting self-supporting structure, which has no columns or beams, is a series of pairs of staircases (154 flights in total), between each of which is inserted a steel spine. The building’s porous structure was designed as such so people could look out of it, as well as in. “We never saw this as an indoor experience, it felt wrong to enclose it,” Dudeney explains. “It was something that generated purely from thinking of the experience of how people would navigate it and what do they see.” The client was always in support of their ideas. “We realise that projects are great when we have a great relationship with the client,” he says. “They were really engaging and involved throughout the whole process.”

A lasting finish

The studio knew they wanted to clad Vessel with something “warm and inviting” to offset the fact that the majority of Hudson Yards’ towers are glass. “We wanted something to counteract that and act as a draw,” Dudeney says. They first looked at copper but were put off by the weathering and changes it would undergo, and the consequent maintenance required. “We designed Vessel to stand for generations,” he explains. Despite disregarding copper itself, the studio still wanted to achieve the same finish, so began exploring alternative options. They looked at electroplating but weren’t convinced, as it “isn’t always super stable”. They then came across a process called physical vapour deposition (PVD), where sheets of stainless steel are placed into a vacuum chamber and exposed to nitric oxide. The gas reacts with the surface of the steel, creating a chemical bond and producing the copper colour Heatherwick were after. It’s a process that has commonly been used on a much smaller scale – such as iPhones and pens, explains Dudeney – but is now being utilised on a much larger scale. “The reason we really got drawn to it is its longevity.

You don’t need to maintain it – the colour will look exactly the same in 90 years.” The material was put through rigorous tests by the studio and contractor Permasteelisa, to see how the surface would react once it had been formed and shaped into the required parts to fit the curved soffit. “We realised once the sheets were coloured they would need to be bent into shape, and we needed to find out what that would do to the surface and the visual outcome of it,” Dudeney explains. The only altering was on the “tightest radius bends” where “you get a slight stretching in the colour but it’s very minute,” he says. “Otherwise it stands up very well to being manipulated like that.” It was also unaffected by being cut where necessary. “There was a huge quality assurance over the whole project and we’re really happy with it,” Dudeney says. As well as being tested for the specific ways it would be manipulated for Vessel, it also underwent testing that put it up against the saline atmospheric conditions of New York. The practice have been so impressed by PVD they’re likely to use it again, says Dudeney. “As a studio we are very interested in materials,” he explains. “We’re always interested in designing through exploration of materials so this is another way for us to expand our knowledge.” They chose not to clad the entirety of the soffit in the copper-look steel – it mostly runs along the underside of each walkway – leaving certain elements of the painted carbon steel structure on show. “New York has a great steel heritage so we were keen to show off the joints and what the structure is,” Dudeney explains. In total there are 75 major steel components – which were built at Cimolai’s yard in Italy. The stainless steel upstand was also added before the components were shipped to site and assembled along with the concrete flooring and glass balustrading. “What they managed to do was fantastic,” says Dudeney. Each splice joint location was influenced by the practicalities of transporting the steel elements and where they needed to be broken up but, he says, “I think it makes the whole thing feel more relatable and interesting.” Everyone working on the project was focused on tackling the constraints of a busy Manhattan site – surrounded by tower block construction – and every precaution was taken to minimise the work needed insitu. Cimolai test constructed the bottom few levels in Italy, and the Heatherwick team would fly out to look at it, check the tolerances and make any necessary changes before the components made their way to the US. “That whole process really helped debug anything that might have happened in New York which was great,” says Dudeney. “Logistically there was a lot of work in terms of getting materials in and out and they did a great job with that.”

Engineering challenges

One of the “major challenges”, says Dudeney, was figuring out just how small they could make Vessel’s base, and how large it could be at the top. “It’s the complete reverse of what buildings normally do, for very good reasons!” he says. “You mix in New York regulations, the physical reality of what carbon steel can do and the structural limitations, and the physical movement and how much it needs to hold – lots of different things over the course of its design affected what you see now.” Dudeney describes the process as “more like designing a bridge in terms of how it’s been put together and the materials that were used.” They faced the “classic” issue of how to balance the components so it would provide the necessary stiffness but not be big and bulky. Their work with engineers AKTII and Thornton Tomasetti was “paramount” in making the structure work. “They did lots of dynamic analysis on it, we had tuned mass dampers all along the top which helped calibrate the whole structure’s movement,” he says. Software was also used to model how people would use it. Surprisingly, the base was another of the most complicated parts. “Once you get up the top the platforms are large, there’s more space – the base is the most constrained element,” Dudeney says. There are four sets of stairs and the lift is squeezed into “the smallest gaps you could possibly have.” The varying angles also proved

a challenge, with every steel and concrete connection having to be thought through individually. While these elements presented challenges, Dudeney found the biggest trial to be the lift, an element that the studio were mainly responsible for. “It is an absolute feat of engineering,” he says. The shape of Vessel meant it had to move on a curve. He explains its unprecedented nature: “To those of us who don’t design lifts, it seems it should be possible, but actually it’s not out there.” The final product was custom-engineered and custom-built by Comai Technologies, and is “one of the more unique experiences on the Vessel”.

Mixed reactions

Since Vessel – which is free to explore – was completed in March, it’s been subjected to some fairly harsh online criticism online. But it isn’t something Dudeney and the team are particularly phased by: “Any project will have negative feedback, and that’s just the nature of it,” he says. “It’s one of the amazing things about this industry, you’re not working towards an echo chamber – you have all of New York and there’s divided opinions. We’re always ready and prepared for that.” Their focus, he says, was very much on creating a public space for people to enjoy – something they’ve undeniably achieved. Nearly one million people have visited since its completion and “that’s people going inside, not walking past and taking a photo,” Dudeney explains. “For us that’s amazing. We always have to work on that broader spectrum.”


  • Designers: Heatherwick Studio
  • Client: Related / Oxford Properties Group
  • Design engineers: AKTII
  • Structural engineers: Thornton Tomasetti
  • Landscape architects: Nelson Byrd Woltz
  • Architect of record: KPF Associates
  • Steel contractor: Cimolai
  • Lift contractor: Cimolai Technologies
  • Cladding contractor: Permasteelisa
  • Crowd analysis: Arup
  • Lighting designers: L’Observatoire International
  • Project management: Tisham