Lynda Tollner is a program director in the World Trade Center Construction Department with design and construction responsibilities for One World Trade Center.
Ms. Tollner has more than 25 years of experience in project management and structural engineering and has worked for the Port Authority for seven years. In the past, she has managed design and construction of a variety of commercial, institutional and transportation facilities including projects at LaGuardia and Newark Liberty International airports and the Port Authority's current headquarters at 225/233 Park Avenue South.
One World Trade Center is scheduled for completion at the end of 2013.
(Note: We received more than 40 questions in response to our "Ask the PA" feature on One World Trade Center. Some of the questions were repetitive, so to avoid redundancy, we eliminated several of them).
Q. When do you anticipate that 1 WTC steel installation will exceed 7 WTC in height? – John, Washington, WA
A. John, we are getting real close. We expect to exceed the height of 7 WTC in February. Right now, we are on the 56th floor.
Q. What do you see as the greatest challenges looking forward toward completion of 1 WTC? – Mike, Moravia, N.Y.
A. We encounter challenges with this project every day and our staff works diligently to meet each and every one of them. Perhaps the greatest challenge we will face in the future is the construction of the 408-foot antenna concurrent with the completion of the roof and the rooftop mechanical systems. Essentially, we will be undertaking two separate projects simultaneously in very limited space.
Q. When do you expect 1 WTC to become the tallest structure downtown, as well as in New York City? Also, why does the first floor of glass skip to every other piece, and finally when will the plaza finishes begin? – Anthony, Commack, N.Y.
A. We anticipate 1 World Trade Center will be the tallest structure downtown by mid-summer when it surpasses the Beekman Tower, and the tallest in the City when it surpasses the Empire State Building by the end of this year. The missing panels of glass on the 20th floor were left out intentionally to accommodate supports for the protection required for the curtain wall glass installation.
Q. When I visited last week, I noticed something strange with the glass. The reflections of things close to the building are very clear, but buildings and objects that are far away seem to be wavy and odd. Is this because the glass has just started to go in? Is there a film on the glass? – George, Philadelphia, PA
A. George, there is no film on the glass. Once the building is fully enclosed and pressurized, the wavy reflection will be reduced.
Q. About what floor will 1 WTC reach by the 9/11/11 anniversary, and what floor will it reach by the end of 2011? – Michael, East Brunswick, N.J.
A. We expect to have steel up to a floor in the mid-80s by the 10th anniversary later this year and near the 104th floor by the end of the year.
Q. There appears to be vents in the façade that cover the large mechanical floors near the top of the building. These mechanical floors and vents also appear to correspond to the original impact site of Flight 11. Is this deliberate or simply a coincidence? – Kyle, Fargo, ND
A. If there is an alignment, as you say, it definitely was not intentional.
Q. How long will it take to reach the 75th floor? – Peter, Verona, N.J.
A. Our goal is to build one floor a week. Given that schedule, we expect to be at the 75th floor in about 22 weeks.
Q. When will the base of 1 WTC by completed in concrete, and how will this process happen? – Zack, Elkton, MD
A. Concrete work at the base of the tower is proceeding, but it must be carefully staged so that it does not interfere with other trades and delivery logistics at the base. Portions of the concrete wall will be done later so that various trades can drive trucks into the lobbies for materials deliveries. For example, all of the elevator rails are being delivered to the North Lobby. Fireproofing materials are delivered to the South Lobby.
Q. Does 1 WTC use the tube-frame structure system like the original Twin Towers? – Benjamin, Canberra, AK
A. No, it does not. 1 WTC involves a building system that consists of a steel frame and a concrete core.
Q. Since the tower is coming closer to being topped out, will there be a topping out ceremony toward the end of the year? – Dominic, Grants, NM
A. We anticipate the tower will be topping out in early 2012. Our focus right now is getting the tower built. When the time comes, we will focus on whatever announcements or ceremony is appropriate. For now, it's just build, build, build.
Q. 1 WTC seems about five floors shorter from street level than the neighboring 7 WTC, which claims a height of 52 floors. Why the difference in height and number of floors? – Josh, New York, N.Y.
A. The number of floors in office buildings does not correspond to a specific height. For example, the first office floor in 1 World Trade Center is the 20th floor, which is approximately 180 feet above street level. However, there are only nine floor slabs between the lobby and the 20th floor, which will accommodate the tower's mechanical systems.
Q. When will the glass façade for the base of 1 WTC be in place? – Tyler, New York, N.Y.
A. Installation of the podium wall glass will begin in early 2012. This work must be staged later to allow the tower's hoists to remain in place, so the podium glass won't be completed until the 2nd quarter of 2013.
Q. I was just wondering when the curtain wall will start on the mechanical floors under the 20th floor? – Spencer, Montreal, N.Y.
A. Just to be clear, the curtain wall and the podium wall glass are not the same. The curtain wall glass is currently being installed from the 20th floor to the top of the building, while the podium wall glass for the bottom 20 floors is in fabrication, with installation to begin in early 2012.
Q. I know that some steel recovered from the site after 9/11 was used to build the U.S.S. New York. Is any of the steel being used to build the new tower? – Joshua, Sparrows Point, MD
A. No. However, there will be two of the massive steel tridents that were part of the original World Trade Center towers on display in the Memorial Pavilion.
Q. When will the spire go on 1 WTC and how long will it take for the spire to be installed? – Logan, New York, N.Y.
A. Installation of the tower's spire will begin in mid 2012, and will take approximately six months to complete.
Q. I noticed a crane on the northwest corner of the building. What will this crane be used for? – Holmdel, N.J.
A. The “slider crane” on the northwest corner of the building is used by the concrete contractor to convey reinforcement and other materials into the building and to remove debris.
Q. How often do shipments of glass arrive at the World Trade Center site? – Erik, Baltimore, MD
A. The curtain wall panels are loaded into shipping containers in Portland, Oregon and shipped by rail to North Jersey, where they are placed on trucks for delivery to the site. We receive one major delivery at the site each week.
Q. Is it true that 1 WTC will top out this year? – Steven, San Diego, CA
A. We expect 1 World Trade Center will top out in early 2012.
Q. I noticed that the crane on the northwest portion of 1 WTC is still attached to the building and no glass panels have been installed on that section of the tower. When will the crane be disassembled in order for the glass to be put up? – Michael, East Brunswick, N.J.
A. As the slider crane moves up the building, the temporary steel on the lower floors is being removed so that the curtain wall installation can continue on this corner.
Q. How many workers are working at 1 World Trade Center at any given time? – Joe, Brooklyn, N.Y.
A. Currently, the total manpower of all of the trades is approximately 1,100 people.
Q. What brand of elevators will be used in 1 World Trade Center? What brand of chillers will be used? – Bob, Louisville, KY
A. Thyssen-Krup will provide 70 elevators and 9 escalators for 1 World Trade Center. There are no chillers in the building. McQuay is providing the self-contained direct expansion air conditioning units on each floor.