June 28 2021
Building a Foundation for the Future with the Manhattan West Platform
In 2011, Entuitive were just opening our doors and within two weeks of doing so we were approached to be part of the Manhattan West Platform in New York City.
Recently, we sat down with Principal Barry Charnish, Principal Mike Hillcoat, and Associate Dave Douglas to discuss how one of the most technically challenging projects we’ve brought to life came to be, and how the award-winning structure continues to present new challenges and opportunities as buildings rise above and around it.
Thanks for sitting down with us today. Can you tell us a bit of background on the platform? What was our initial role?
Barry Charnish (BC): This was literally just as we were starting up as a company. A previous team of engineers had come up with a proposed scheme constructed of structural steel with 15 columns placed between the existing rail tracks. We were called in by Brookfield to come up with an alternative idea that would be less impactful at track level.
We had two weeks to come up with an idea. We did some research and played off the idea of eliminating all columns and not touching down into the rail corridor. Working at track level is costly to do, especially because the railway is in constant use. Extended closures of any of the tracks leading into Penn Station were near impossible.
We thought, “Isn’t this platform really a bridge?” and, “How do they build bridges?” So, we looked at steel and a number of alternative materials, including segmented post-tensioned construction. This is the kind of construction you see in the grand, modern long-span bridges in the Alps and places like that. The erection of these bridges is frequently achieved using a purpose-built launching unit that pushes the bridge segments across from pier-to-pier.
We tried to establish what the risks were with this idea. For instance, if the segments got too big, we would be able to get them onto a truck and over the bridges into Manhattan. So we had to investigate truck limitations in size and weight. We felt that we could realistically get a structure depth that was 12 feet high.
At the end of the two-week period, we drew up a quick design to see what this would look like, whether it would work, and how we could support moving the project forward. We went back to Brookfield (our client) and convinced them that this was something worth exploring.
We then had six weeks to prepare a pricing package to shop to the trades. There was a similar sort of bridge construction going on in the New York area, and there was a contractor, Rizzani de Eccher, that was doing one of these. Brookfield brought Rizzani in to get numbers from them and that sprung the whole project forward.
Obviously, this was a huge project for us. How have we seen the significance play out long term?
BC: These days we’re seeing an increased focus on transportation and transit-oriented developments. We’ve leveraged our work on Manhattan West as an extreme example of how you can build over subways, LRTs, and roadways. This project is kind of like the ultimate case study – 16 rail lines right in Manhattan.
Mike Hillcoat (MH): For me, the significance is that our client put a lot of trust in us as a relatively new company. We played a major role in making this extraordinarily high-risk project a reality. Brookfield were trying to build over the busiest rail line in North America without interrupting the trains travelling underneath. It’s significant for Entuitive that Brookfield, a major international developer, trusted us with not only the design, but also the development of the erection methodology for such a sensitive and complex project. It’s brought Entuitive continued recognition for our technical expertise and our willingness to pursue complex construction engineering projects that include erection methodology and means and methods.
BC: I think the best example of trying something new and complex might be the launcher. The launcher is the big piece of equipment used to erect a bridge. The client asked us to specify what this launcher, this $10 million piece of equipment, would look like. We did quite a bit of research and decided that we were going to need to lift and place the roughly 2,400-ton concrete spans within a ¼ inch of their target. A lot of rigour had to go into writing a performance specification so that this was achievable.
We asked ourselves, “Is that even practical? How do you design this?” and, “How fast does it move?” We were thinking of putting it on the tracks and looking for equivalencies in crane design, trying to decide how you design a crane to hold a 30,000-pound coil of steel.
We also had to look at each of the 16 spans. The weight of the last span that the launcher had to place was right at its limit. How do you place this thing between the existing 9th Avenue Bridge and Span 15 with only about a 1” gap to work with? I literally wrote a machine spec for the first time in my life. It was the most challenging project I’ve worked on.
Dave Douglas (DD): I think it’s important to recognize how quickly this became a construction engineering exercise. There were those initial two weeks at the beginning of the project and from there we quickly homed in on constructability, looking at bridge clearances and how you can get the materials in. Then we had six weeks to study what this would actually look like. Brookfield came to us because they recognized that this project was more of a construction engineering exercise than a pure structural design project. There would have been many ways to build a platform like this if you had all the space in the world, but in this location, the key differentiator was really in the logistics of building it.
Looking back, almost ten years later, have we continued to play a role and what has that role been like if so?
MH: The platform itself was primarily built to protect the tracks below in order to allow Brookfield to construct two office buildings, a residential building, a hotel, and some retail over the tracks. The platform became a staging area on which to place cranes and stored materials for the erection and construction of those towers. The platform was very heavily utilized throughout the construction of the adjacent towers, piled right up to its maximum capacity with materials and some of the heaviest mobile cranes on the planet. Entuitive continued to assist Brookfield and the multiple contractors reviewing loads on the platform, limitations on crane placement, and what kind of outrigger loads the platform could accommodate and where. These loads were anticipated at the time of construction, as it was always meant to be used as a construction staging platform. But from time-to-time certain massive picks required close attention and review.
Three of those buildings have been completed now and the final one is still under construction. There continue to be significant loads imposed on the platform.
DD: The platform remains a living part of the site beyond its staging capabilities. All these buildings have and continue to go up around it, and there are interfaces between those buildings and the platform with the support of permanent elements like walls and new stairs. There’s also a massive high-pressure steam line. We continue to be involved, coordinating with these other developments on the site and making modifications and responding to modifications to the platform structure as they arise.
You’ve mentioned several collaborators we’ve worked with on the project. What has it been like work with so many different people on this project?
MH: I have a fond memory working with Rizzani de Eccher, because the launcher and post-tensioned segmental precast construction were all very new to me. I was extremely impressed – blown away, even – by their lead engineer Daniele Tosoratti, who led the final design of the Launcher. Daniele was proficient in structural, hydraulics, electrical, and mechanical engineering, all of which were required to design this thing. It was a combination of skills I’ve never seen in the building construction world. So it was quite inspiring for me. We had the opportunity to work with this amazing company, and we’ve subsequently worked with them on 550 Washington in New York. They’re a great company to be teamed up with on complicated projects with multi-disciplinary constructability considerations.
DD: I would say Metropolitan Walters has been great to work with as well. We began our work with them at the very beginning of the platform construction, continued our collaboration through the construction, and are still interfacing with them on site today as new considerations arise. Our relationship with Metropolitan Walters has also continued on at 550 Washington. Along with Rizzani, we formed a winning relationship where we can come together to design unique, revolutionary structures.
MH: A unique challenge on this project was that we had to build on and excavate a heck of a lot of rock. It sounds straightforward but when you’re talking about Manhattan schist it’s not a straightforward operation. It was extremely impressive to see Civetta’s approach and methodology for excavating this rock in a very organized way that kept things on schedule. Rock excavation adjacent to and between rail tracks is difficult work, and Civetta ran an impressive operation on both the laborious rock excavation and the construction of the foundations we had designed.
Turner and Tishman Construction were both involved at different stages in the project as construction managers, and both have been exceptionally good, acting as true construction managers, representing the owner’s interests well, as opposed to focusing too much on looking after their subcontractors. Since Manhattan West, I’ve worked on projects with every conceivable project delivery model, and construction management is by far the best when it is executed properly. Both Tishman and Turner have really professional staff and are excellent people to work with.
BC: I couldn’t agree more with what Dave and Mike have said. With this project we experienced an even higher level of collaboration than we tend to see on most of our Design Build or P3 projects we get into. On well structured construction management projects you feel you’re truly one team.
DD: I came in well after Mike and Barry, after the platform construction had begun. I walked into a room with Turner and Metropolitan Walters and I could really feel the sense of being part of a team. Everyone was very coalesced around the development, the construction, the coordination – I don’t think a project like this comes together without the close collaboration fostered between the engineers, the contractors, the subcontractors, and the owners. Brookfield did a great job of managing this.
MH: What I’d like to say specifically about Brookfield is that they listened to the experts. To be honest, there’s nothing more rewarding as an engineer than when you express your opinion and you’re firm on it, and that opinion is trusted. It’s becoming more and more rare as structural engineering becomes a bit more commoditized on high-rise residential buildings where engineers are selected based on the lowest fee and much of the design can be done remotely without a true understanding of the client’s needs or the challenges of the site. When you get into something incredibly complex and unique like Manhattan West, you can’t look to a similar project to find a solution. You need to rely on the experience of good engineers to help you. Brookfield did that and it brought a lot of satisfaction to the entire team. The project was very collaborative and that was rewarding for everyone.
Any final thoughts that you think we should cover?
MH: It’s probably worth noting that there are many opportunities for this kind of development – rail overbuild projects – in many cities throughout the world. I would recommend that developers consult people who have worked on successful overbuilds early on in the process to learn about what was successful. A project delivery method that encourages collaboration between all parties is critical to getting these projects off the ground. I see a lot of these potential overbuild projects sitting in limbo due to politics and conflicts between the parties. The Manhattan West site had those challenges as well and Brookfield set a tone of respect and encouraged creative thinking to cater to the interests of all stakeholders, which enabled the project to get built.
Thanks for sitting down with us today, Barry, Dave, and Mike. We learned a lot!