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INSIDE: THE TOP 100 PROJECT DELIVERY FIRMS

JUNE 12, 2017



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ICONIC EYRIE

UPGRADE THE EMPIRE STATE BUILDING’S STEEL BROADCASTING TOWER? WEAVE A SKYSCRAPING, HURRICANE-DEFYING WORKERS’ NEST FIRST (P. 26)

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6/5/17 6:18 PM

SEPTEMBER DAWN

By the light of blue LEDs illuminating the top of the Empire State Building, Local 40 ironworker Ruben Villagran nears the end of another shift at 6:10 a.m. He is working on one of the aluminum truss towers of the Haki Trak system, whose vertical rails capture and support the ballisticfabric walls of a workspace cocoon.

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hen engineers made plans to reinforce and upgrade the carrying capacity of the Empire State Building’s mast and tower by adding 39 tons of steel, they had to find a way to protect pedestrians from falling rivets, tools and materials. Roofing the observatory and building bridges over the sidewalks 1,250 ft below were lousy options. The top of the iconic New York City building has an open-air observatory at the 86th floor and premium viewing spaces at the 102nd and 103rd levels. Annually, these spaces host about 4.3 million visitors and generate about $85 million in revenue. Soaring above the busy streets, a 200-ft-tall steel broadcast tower bristles with antennas that generate about $20 million more. Together, the

CHRYSALIS

Workers weave a cocoon of steel, aluminum and cloth to create a safe work space far above the streets of Manhattan By Tom Sawyer 26

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PHOTO BY TIMOTHY SCHENCK, COURTESY OF SKANSKA USA

SPINNING A

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BROADCAST HUB

PHOTO (LEFT) COURTESY OF SKANSKA USA. DRAWING (RIGHT) COURTESY OF THORNTON TOMASETTI WITH ILLUSTRATION MANIPULATION BY EVA SAWYER

The mast of the Empire State Building is topped by a premium, glazed observation space at the 102nd floor and an open-air VIP parapet at the 103rd. A temporary, hard-sided workspace and support for the “cocoon” brace back to the conical ice shield above the VIP parapet; the cocoon floor is at the top of the steel panels. Fabric panels rise about 25 ft to a solid roof. The cocoon surrounds the lower part of the broadcast tower, which has just been reinforced to carry backup antennas for a similar array (here, seen above the worker on the cocoon roof). To improve future configuration flexibility, the strengthening goes well beyond immediate requirements.

observatory, mast and tower are the crowning jewel of the 86-year-old icon, which is owned by the Empire State Realty Trust Inc. COVER STORY The search for an alternative to PROJECT DELIVERY scaffolding dates to February 2014, when the ESRT’s building engineer, engineer-ofrecord Thornton Tomasetti, site safety engineer Plan B Engineering and contractor Skanska Buildings USA Inc. began to consult with New York City Dept. of Buildings officials to devise a plan that would not only protect the public and workers but also allow for the strengthening of the mast and tower without having to resort to sidewalk bridges. They came up with a design for a sheltering “cocoon,” which sits on a 560-sq-ft aluminum elevated work platform, or “dance floor.” The platform is braced from below by steel brackets through the conical ice shield, which is there to shatter ice falling from the tower. Further, the outer edges of the dance floor are guyed by cables leading up to the roof of the cocoon and the tower above. Encircling the exposed base of the tower just above the ESB’s roof, the floor is enclosed by walls created by aluminum truss towers arranged in an octagon and bridged by panels of ballistic cloth, which slide in edge tracks from bottom to top. To reduce exposure to dangerous winds, the panels can be drawn down in a few minutes by rollers. “The planning of the project took two years, including six months to design the cocoon and [perform the wind] testing in Florida,” says Tom Durels, ESRT’s executive vice president and director of leasing and operations. “That gives an idea of the amount of thought and engineering that went into it.” The assembly is designed to meet city codes for a 300-psf live load and a three-second wind gust of 98 mph. “It was wind-tunnel-tested to failure at 140 miles per hour, and it was the test-sample support structure that failed. It wasn’t the envelope,” says Peter Sjolund, the ESRT’s senior vice president of construction. “You are on the top of the Empire State Building, the most famous office building in the world. You don’t want to be on ‘film at 11.’ ” Stealthy Work Scott Seydor was project manager for the cocoon construction. An architect, he joined Skanska USA in 2011 as a design manager for mission-critical, design-build data-center work, which brought him to the attention of Skanska executives looking for someone with a strong design background to manage mission-critical work in the Empire State Building, he says. One one

Existing tower with new steel panels Handrail Cocoon roof

Cocoon tower Fabric panel

Handrail Lightgauge steel siding

“Dance floor” support

Ice shield

such project, Seydor managed the replacement of the Art Deco mast’s 480 pieces of glass between the 90th floor and 101st floor. When he heard of the mast-strengthening project, Seydor says he jumped at the chance to manage it, too. “I said, ‘We can do it right. We can do it safe. Let me do it. The project needs to be done.’ ” He adds, “I live in Philly. I get up at 3:30 in the morning because I get to do this. … I am an architect, and this is the most iconic building in the world.” Few New Yorkers—not to mention the hundreds of thousands of annual visitors who meander around the observation decks—are aware of the work being performed above them by a small Skanska USA crew and the handful of steelworkers from Skanska Civil NE, a sister business unit. “It’s such a small space, there’s only so many guys you can throw at it,” Seydor observes. Because the materials-handling path makes use of the passenger elevators and public observation areas, crews had to construct and, starting this week, will

TOPPER The

temporary cocoon structure encloses the base of the broadcast tower as it emerges from the truncated cone at the building’s roof.

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PHOTOS COURTESY OF SKANSKA USA

have to deconstruct the cocoon between the hours of 2 a.m. and 7 a.m., when the public spaces are closed. From the loading dock, materials are navigated through security scanners, down to a lower concourse and up a service elevator to the 79th floor, where they are carted to a passenger-elevator bank for a lift to the 85th floor and then transferred to a manually operated 1930s “mast elevator” for a ride to the 102nd floor. After that, materials are hoisted up ladders and through hatches by hand and with chain falls out through a single “submarine hatch” in the flat-topped conical roof that crowns the building. Due to handling constraints, including the size of the legacy elevator in the mast, the largest piece taken up was a 6-ft, 4-in.-long W12 steel beam, says ESRT’s Sjolund. A support for the platform framing, it weighs 2,833 lb. To maneuver beams out of the submarine hatch and into place, the assembly sequence first required the installation of chain hoists on lifting booms projecting from the tower. The steel beams were placed first, building up the ice-shield roof just beyond the perimeter of the planned dance floor. Then, crews erected a hard-sided wall around the first work area to prepare for assembly of the dance floor, just above.

LOGISTICAL CONSTRAINTS

Ultimately, all materials are delivered by brute force up a series of ladders and out through a submarine hatch in the ice shield. The first workspace was created on a temporary extension of the skirt around the ice shield, which was given steel-sided walls to protect the workers as they next assembled the aluminum platform and fabric cocoon above.

Creating a Safe Space While there is only a few feet between the cone and the hard side, the clearance creates a small storage area and just enough of a safe space to bolt and splice the hundreds of pieces of aluminum beams, floor plates and vertical truss sections required to create the aluminum floor, towers and roof of the cocoon, which begins just overhead.

The purpose of the work is to increase the steel tower’s carrying capacity by beefing up the lower section of tower above the roof, as well as by reinforcing its ties into the structure. The ironworkers accomplished the work with hundreds of pieces of ¾-in.-steel plate and bar, stitch-welded and bolted to the existing steel. The maximum dimensions and weight of the components are strictly constrained by the tortured logistics required to get them there and the frequent need to fit them between and around the structural features of the existing tower. “If we could have brought up 25-foot-long pieces, we would have loved it,” says Sjolund. The strengthening work included several phases, the first of which started in fall 2015 and involved strengthening the tower legs as they enter the building’s roof and carry loads down to the 101st level. Crews added bars and plate to the existing steel by replacing rivets with longer torsion-control bolts or fitting plate between existing members and introducing new braces, gussets and diagonals. On the 101st to 103rd levels, the interior work required opening ceilings, walls and floors in public spaces and was conducted during an around-the-clock, three-week push during February and March 2016. It was the only part of the work that interrupted visitor access to the observatory spaces, and the interruption affected only the smaller, premium spaces on the 102nd and 103rd levels. Work inside the completed cocoon enabled the next phase of the tower strengthening. “The cocoon allowed us to work uninterrupted through inclement weather and 24/7, without disruption to our broadcasters,” Sjolund says.

COVER STORY

PROJECT DELIVERY

SAFETY, SAFETY, SAFETY Wearing climbing helmets and fall protection, a crew of about a dozen Local 40 ironworkers assembled the 22-ton cocoon, beginning in late May 2016. The first steps were in the open air, but by the time the cocoon was finished and the workspace enclosed, “you could have been working in your basement,” says Scott Seydor, Skanska’s project manager through the assembly phase. The sound of the faraway city streets are lost when the wind rises and the cocoon’s fabric sides start rustling like luffing sails.

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TEMPORARY WORKS

Part of the temporary works installed to facilitate cocoon construction, outriggers and chain hoists jut from the tower above the cocoon’s hard roof. The cocoon roof and deck were engineered for 300-psf dynamic loading and impacts from falling objects, as per code. The new screen antenna array will be installed in the space where the cocoon is now; the new array will look like the existing array (at left, between the Xshaped “turnstile” antennas). The turnstile antennas are scheduled for removal. The tall white column is a digital television antenna installed for CBS in 1999.

To strengthen the tower, crews welded and bolted on additional steel. Further, crews enclosed the lower part of the tower in new steel plate. COVER STORY When workers need to de-energize PROJECT DELIVERY and service the existing upper antenna array, the new, lower backup antenna array will be used to continue broadcasting and its steel-plate backing will protect the workers from radio-frequency radiation as they climb up.

Antenna Upgrade The mast’s antennas are licensed to third-party television and radio broadcasters and data communications providers. Further, space in the building’s upper floors is leased to house transmission equipment and related facilities, including “multichannel combiners” that send broadcasts of multiple frequencies through common antenna arrays. Nineteen FM radio and about a dozen television channels currently broadcast from the tower. The FM stations use either a primary array about 100 ft above the building’s roof or, lower down, the 50-year-old Alford Antennas backup array, to which signals can be diverted when changes or repairs are needed on the primary array. Signals are conducted from the channel combiners on a lower floor via 31/8in.- or 61/8-in.-dia copper-clad coaxial cables in nitrogen-filled jackets. “We call it plumbing—think … of 6-inch-diameter copper pipe,” says Ed Driscoll, the ESRT’s manager of broadcasting. The big copper lines rise through the upper floors and travel up the tower to the antenna. Having run additional lines for the new backup array, the antenna installers will soon start to hang the 4.5-ton backup array on the now-strengthened tower. Work will begin after the cocoon comes down in mid-June. A 2014 reconfiguration plan mapped out an upgrade to the tower’s antennacarrying capacity. The addition is driven by market forces, according to the ESRT’s most recent quarterly SEC filing. “The business of broadcasting TV and radio signals over the air is in flux, due to deteriorating industry fundamentals and the ongoing Federal Communications Commission spectrum auction, and there is competition from other broadcasting operations,” the statement acknowledges. New generations of broadcasting equipment are expected to begin populating the tower in the months and years to come.

TOWER SET

A triangular “Tomcat Truss” tower segment is set in place (above) as the cocoon frame takes form. All assembly work atop the building had to be accomplished between 2 a.m. and 7 a.m., during the hours when the public observation areas below were closed. Now that the tower strengthening has been accomplished, cocoon disassembly soon will begin.

Moving On “One of the things about working on the Empire State Building, the world’s most famous building, is we are constantly innovating and have the benefit of working with the world’s leading experts,” says ESRT’s Durels. “Building this protective cocoon is an example of that,” he notes, adding that the project “may lead others to see what can be done on towers worldwide when it comes to this type of work.” Seydor will not be around for the cocoon demolition. After years of getting up at 3:30 a.m. and commuting 240 miles a day to lead what he calls a project of a lifetime, the project manager has moved on to work closer to home at Genesis Engineers, Plymouth Meeting, Pa. “It was … an incredible project. They knew it wasn’t just a job to me—it was a passion,” he says. “This is the Empire State Building: Things are different here.” n

HANDCRAFTED Worker (center) positions a Hugen portable drill

to make a hole for a torsion-control bolt to fasten steel plates to the existing tower structure. Once positioned, a switch activates the drill’s electromagnetic base to hold it in place. Ironworkers (above) adjust a template to mark locations for new holes. PHOTOS COURTESY OF SKANSKA USA AND ESRT

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