高生活：定位美国最高的住宅建筑的地板

Author:T/F/D

On Manhattan’s ‘Billionaire’s Row’, a new 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

中央公园塔将与一个包含179个家庭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.

为每层建立控制线

The Leica Geosystems GNSS-based monitoring system works by GNSS receivers being placed on the outside of the building − the hydraulically climbed protection screen enveloping the structure in this case − and acting as control points that move up as floors are completed. The system used on the Central Park Tower construction included fourLeica AS10 SmartTrack antennaswith co-located 360 prisms, aLeica GM30 GNSS监视接收器，Leica Viva TS15 Total Station（前身Leica Viva TS16) andLeica Spider和地缘监测软件. Mandelbaum explains, “The脚手架保护屏幕爬上建筑物，因此我将所有设备都放在上面。我不必担心我会身体移动，因为它已固定在屏幕。GNSS天线，我将在建筑物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，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 16^thof 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

尽管是GNSS系统的新手，但Mandelbaum和他的合作伙伴发现它很容易使用。在Leica的支持下，通过拍摄手机上的一些流程以供参考，他说：“这很简单。”一个自认的机械师，而不是“软件盖伊”莉卡（Leica）的软件程序 - 现在是莱卡蜘蛛软件套件和莉卡·吉莫斯（Leica Geomos）！- 可轻松访问建立控制线必不可少的实时数据。“我需要学习一些步骤，仅此而已。那是小菜一碟。”

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.”

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