A Star is Born: Custom Beacon Shines Atop One World Trade Center
Often described as one of the world’s biggest stages, New York City recently got another star. This one crowns a patriotic building being erected on the site of the 9/11 terrorist attacks. It’s a one-of-a-kind beacon installed on the top of the new One World Trade Center tower in lower Manhattan, which will be the tallest building in the Western Hemisphere when it opens in early 2015.
The energy-efficient beacon will shine at 1,740 feet above the streets of New York; the new tower will reach a patriotic height of 1,776 feet. “The antenna structure is approximately 400′ tall and consists of 18 separate segments,” explains Tom Trytek, P.E. of TDK Engineering, which partnered with J.R. Clancy in completing the project. “The beacon is in the last segment.”
The light itself is made up of 16 suitcase-sized petals, each containing 11 modules of LED lights. The bottom petals each contain an array of 22 LED modules. Each module produces 1,200 lumens on its own, for a cumulative total of 316,800 lumens – a light that will be seen easily from Manhattan to New Jersey, even on a foggy night.
The petal array lives in a stainless steel structure with large mirrors located between the LED modules to maximize and direct the light across the city, says Bridget Cox, J.R. Clancy’s director of project management. “The ‘mirrors’ themselves are not actually glass, but are specialized laminated assemblies of honeycomb board with a custom reflective aluminum surface,” she says.
The light sources remain stationary, while the mirror assembly rotates on a small, motorized turntable. A computer supplied by Barbizon Lighting sends a signal to the motor control cabinet, turning the beacon turntable on every day an hour before dusk, and shutting it off an hour after sunrise.
The beacon’s creation was the kind of design engineering, manufacturing and installation challenge that comes around once in a lifetime. The project team was a talented ensemble whose members had honed their individual skills and cooperation working on theatrical rigging projects, which are J.R. Clancy’s specialty and primary business.
When Ballantyne Strong, the entertainment lighting and projection system company, was selected to create the beacon, they reached out to Clancy.
“Clancy was always the first choice because they had been world renowned for their expertise on custom fixtures,” says Glen Thor, director of Strong Lighting. “Clancy president Mike Murphy and Strong’s engineering team got together on the project over the next 13 months of engineering work, and we were able to get it to the finish line in less than half that time.”
Strong also worked closely with lighting designer Claude Engel through the preliminary phases of the project. The motorized turntable, mirror assemblies, and electrical components were built by a manufacturing team led by Clancy, with the assistance of Blair Construction and Fabrication in Auburn, NY.
High Installation, Low Maintenance
The team paid special attention to reducing potential maintenance and repair issues. “The entire beacon is exposed to the elements, so it had to be designed to withstand New York City heat in the summer, cold in the winter, and precipitation,” says Cox.
“There’s a special enamel paint treatment used for all of the parts that could not be made out of stainless steel. The stainless steel motor control cabinet can withstand the summer heat intrinsically, but if the temperature drops below 40 degrees, internal heaters kick on to keep the control components at a relatively constant temperature. The turntable motors are also equipped with heaters to help avoid condensation.”
Designing a super-bright lighting fixture is challenging enough, but the fact that this beacon lives above 1,700′ required the design team to think through every aspect of maintenance and repair.
“The specifications from the architect were that the beacon was to be fully capable of being dismantled and replaced in place,” says Trytek. “The beacon is segmented, so every component can be removed individually and replaced.”
Clancy and TDK examined every aspect of the original design to determine the best ways to simplify and ruggedize the structure, reducing the likelihood of a mechanical breakdown.
The turntable structure involves a slew ring bearing — a single large, circular bearing with a projected life of one billion revolutions. “It turns as fast as a second hand, and it operates roughly twelve hours a day,” says Trytek. “With proper maintenance, it could last almost forever.”
A second gear motor in the turntable provides a redundant motor drive system so the beacon would still operate if one of the motors malfunctioned.
“The slew ring is so much simpler, with an infinite lifespan, and it’s very easily serviceable,” says Thor. “Ours was a motor track system that would have required much more maintenance. I have to give TDK and Clancy credit for coming up with a better solution that saves everyone a lot of time, effort, and money.”
In the Spotlight
Even with all of these precautions, the team knew that service personnel would need to access every part of the World Trade Center beacon for routine maintenance and repairs — both for the beacon itself, and for the components above it.
“Through the center of the mirror system is an access ladder,” says Trytek. “Just above the beacon on the tower are four FAA lights, as well as a light at the very top of the antenna. So we had to be sure that a maintenance person could pass through without interfering with the mirror, to reach the lights at the top of the tower.”
While some of the mirror panels are fixed to the frame of the beacon housing, the center panels can be removed, “sort of like a leaf in a table,” Trytek explains. “Each of the leaves of the mirror system can be stored to the left and right sides of the mirror frame. So you have an unobstructed way to get to the upper and lower petals of the LED system.”
With the beacon soon to cast its light across Manhattan, Thor is quick to praise the expertise the Clancy team brought to the project. “Clancy’s role has been instrumental; we couldn’t have done it without them,” he says. “Between the three companies, there has been a personal level of trust and understanding. I trusted that they were doing the right thing, and that was the key for me.”