The high life: Locating the floors of America’s tallest residential building
Case study
Author:T/F/D
在曼哈顿的“亿万富翁的行”,一个新的glistening New York skyscraper nears completion. The Central Park Tower rises to 1,550 feet (472 metres) tall, the tallest residential building in the world, and the second tallest building in the city, second only to One World Trade Center. Construction began in 2014 and Pinnacle Industries II, LLC installed the core super-climber forming system in 2016. Due to the height of the building, Robert Mandelbaum, Survey Engineer at Pinnacle Industries II, used a GPS solution − a Leica Geosystems GNSS system − to locate the layout of each new floor.
A new approach to monitoring
Central Park Tower will contain 179 homes with one of the most expensive views in the world. 300 feet (over 91 metres) above the street, the Tower cantilevers to the east, creating views of Central Park for all north-facing residents. The elegant exterior gives away nothing of the complexity of the construction or the challenges of keeping the building’s footprint consistent and accurate. Before each new floor could be built, Mandelbaum needed to provide the Pinnacle Industries II team with reliable coordinates to set out the structure. On a smaller building, surveyors would use optical instruments to do this from the ground, but above a certain height that becomes impossible. “Because it’s so high, we cannot use conventional transits [transit levels] to establish location,” explains Mandelbaum. “On a bad weather day, that’s just not happening. At 1500 feet (over 450 metres), you cannot see with a traditional instrument.” So, for the first time on a residential construction site, Mandelbaum used a GPS-based solution.
Establishing control lines for each floor
Leica GeoSystems基于GNSS的监视系统的工作原理由GNSS接收器放置在建筑物的外部 - 在这种情况下，液压攀爬的保护屏幕包围了结构 - 并充当随着地板完成的控制点。中央公园塔建筑上使用的系统包括四个Leica AS10 SmartTrack antennaswith co-located 360 prisms, aLeica GM30 GNSS监视接收器, Leica Viva TS15 Total Station (the predecessor ofLeica TS16) andLeica SpiderandLeica GeoMoS monitoring software。曼德鲍姆（Mandelbaum）解释说：“保护屏幕爬上了建筑物，所以我把所有设备都放在上面。我不必担心我会身体上移动它，因为它已固定在屏幕的内部。GNSS天线，我将在大楼的每个角落都放在彼此之间。他们会给我坐标，并使用我能够建立控制线。”控制线标记了建筑板边缘的位置以及柱子和墙壁的位置和定位。
Proven accuracy in a high-pressure environment
The most significant benefit of the system to the Pinnacle II team, says Mandelbaum, was its accuracy, reassuring when working on any construction site, but especially a high rise. He used a traditional technique to check the GNSS measurements. “To verify that the access lines or the control lines stack from floor to floor, every 10 floors, I would use an old school piano wire. Literally a piano wire, and drop it through a corner. I would tie a good 80 lb weight to the bottom of it, and I would physically check with a rule to the access lines on the floor, to the control lines. And it was there, within a 16Thof an inch (1/6 inches = 1.55mm accuracy). It just proved that it’s right.”
A Leica Viva TS15 Total Station was also used to establish the position of the control lines, acting as another independent check of the solution which could be referenced against the antenna readings. The total station positioned itself via prisms co-located under the GNSS antennas. Mandelbaum explains, “I would know where each antenna is according to the solution on the laptop. I would take the antenna that’s the farthest away from me, and I would look for the time solution as well. I would be at the same time slot and shoot (measure with the total station) the antenna. And if it’s the same number that I see on the laptop, within a few thousandths, then I will use it.”
Easy to use software displaying real-time data
Despite being new to the GNSS system, Mandelbaum and his partner found it easy to use. With support from Leica and by filming some of the processes on his phone for reference, he says “it was pretty simple.” A self-confessed mechanic rather than a ‘software guy’ Leica’s software programs − the Leica Spider Software Suite and Leica GeoMoS Now! − provided easy access to the real-time data essential for establishing control lines. “There were a few steps I needed to learn, and that was that. It was a piece of cake.”
Construction of Central Park Tower is due to complete in 2021. Now that Mandelbaum’s part in the build is finished, he plans to use the Leica Geosystems GNSS system again: “If I can, I will. It has a track record that it works.”
有兴趣监视吗？请随时阅读进一步的案例研究，显示我们的客户如何使用我们的解决方案来改善其监视工作流程：
