NFPA Journal

NFPA Journal®,  July/August 2012 

BY Fred Durso, Jr.

The task seemed monumental: Take a 19th-century structure towering 305 feet (93 meters), implement an assortment of safety improvements that comply with today’s codes and standards, and make sure the upgrades only minimally impact the structure’s historic fabric.   

If anyone could endure such rigor, it’s Lady Liberty. Celebrating her 126th birthday this year, she’s withstood the test of time (with the help of a facelift in 1986 for her centennial) and is now undergoing needed repairs and upgrades to her interior. The U.S. National Park Service (NPS), which maintains the monument, has initiated a series of fire and life safety improvements — at an estimated cost of $29 million — in advance of allowing visitors to once again access observation areas in the statue’s pedestal and seven-point crown.

But upgrading such a unique and historic structure wasn’t as simple as following provisions in relevant codes and standards. What actually occurred was a constructive integration of safety and historical preservation, a task that was achieved with assistance from NFPA 101®, Life Safety Code®; NFPA 72®, National Fire Alarm and Signaling Code; and NFPA 13, Installation of Sprinkler Systems. “It was the goal of the Park Service to make [the monument] as code compliant as possible without impacting key historic elements,” says Michael Ferreira, senior engineer at Hughes Associates, the consulting firm that developed a series of recommended improvements to the Statue of Liberty. “One of the unique aspects of this project was that decisions were made with numerous types of stakeholders, not just engineers.”

Grand reopening
Immediately following the terrorist attacks of September 11, 2001, public access to the Statue of Liberty was prohibited for security and safety reasons. Three years later, following a $20 million safety upgrade to the monument that included accessibility improvements and the implementation of a tour reservation system to manage crowds, the NPS reopened the pedestal’s observation area to visitors.

Secretary of the Interior Ken Salazar permitted limited access to the crown’s observation deck in 2009 and promised that enhancements to the monument’s interior would continue in order to enhance its safety since aspects of the monument, particularly the elevators and means of egress, weren’t code compliant.

Before Salazar’s decision, however, congressional members from New York led a push to initiate a life safety and emergency assessment of Lady Liberty. The House Subcommittee on National Parks, Forests, and Public Lands asked NPS two key questions during a hearing in 2007: What physical changes to the structure would be required to bring it up to code and safely allow access to the crown? Moreover, how could NPS minimize risk to staff, visitors, and emergency management personnel if upgrades were not fully code compliant?
                                     
Seeking answers, NPS sent a bid to engineering firms eager to perform the requested analysis, and selected Hughes Associates in 2008. “Based on their reputation and experience with fire safety, Hughes had the best technical team,” says Hugh Duffy, Denver Service Center project manager with the NPS who is overseeing the monument’s improvements.

Hughes engineers consulted the Life Safety Code — mainly provisions related to egress — during their initial research on bringing the monument up to code. Based on its size and ability to have an occupied floor 75 feet [23 meters] above grade, the monument is considered a high-rise structure and adheres to code provisions for such structures. Following completion of fire and egress models of the structure, Hughes presented its findings, along with a series of recommendations, to the NPS and New York’s State Historic Preservation Office (SHPO), which provides input on culturally significant projects. (Citing security concerns, NPS did not permit Hughes to share the results of its study with NFPA Journal.) “SHPO is consulted on all state and federal projects that may impact historical properties in New York State and makes recommendations to avoid or mitigate any adverse impacts on historic resources,” says Sally Drake, spokesperson with the New York State Office of Parks, Recreation, and Historical Preservation.

SHPO considered Hughes Associates’ recommendations, which included features that would make the overall structure — the 154-foot [47-meter] pedestal, as well as the 151-foot [46-meter] statue — fully compliant with the city’s building code. SHPO determined that some of the proposals would have had more-than-minimal impacts on the monument’s “historic fabric,” according to Ferreira, including the statue’s copper sheeting — just .09 inch [2.3 millimeters] thick, or about the thickness of two pennies placed together — as well as the internal framework supporting the structure and the double helical stairs in the statue leading to the crown. “To make [the stairs in the statue] fully code compliant, you’d have to remove them and replace them with two enclosed stairs within the body of the statue,” says Ferreira. “That wasn’t practical or desired.”

A similar process was used to determine the level of fire and life safety that would be achieved throughout the structure, including the areas that were particularly sensitive to “historic fabric” considerations. The Hughes recommendations included computer models addressing life safety hazards, fire protection options, and means of egress, Ferreira says, so that designers were always aware of the effects that fire safety and historic preservation had on each other.

SHPO regarded other aspects of the monument as less integrated with its historic fabric. For example, the main elevator and staircases in the monument’s pedestal that lead to the pedestal’s observation platform were last replaced in the 1980s for the monument’s centennial in 1986 and were not up to current building and life safety codes. Upgrading these elements would require the removal of concrete that was poured during the statue’s construction in the 1800s. “It was viewed during the evaluation process that certain historical aspects…[such as the concrete] in the pedestal weren’t as important as what was in the statue itself,” Ferreira says.

Guidelines for such decision making are at the core of NFPA 914, Fire Protection of Historic Structures, which was developed to address precisely this type of project. NFPA 914’s process is designed to identify normal solutions that don’t work for historic buildings and to replace them with innovative approaches — “close-to” code design, equivalencies, management operational controls, and more — that maintain a structure’s historic fabric while also achieving fire safety goals.

Necessary adjustments 
The first phase of improvements was to the original double-helical stairs that spiral within the statue. Rather than replace the stairs, which did not comply with code-required riser heights, tread depths, and headroom measurements, contractors installed handrails and guardrails for added safety. (Chapter 7 of NFPA 101, which outlines means of egress requirements, includes a “guards and handrails” section for new and existing stairs.) The upgrades now permit visitors to safely descend both stairs in an emergency. Protective glass sheets were also placed in certain areas near the stairs where the handrails and guardrails couldn’t go, thus serving the same purpose as guardrails and preventing visitors from touching aspects of the statue’s historic framework. Contractors secured the glass using specially designed clamps in an effort to avoid drilling into the structure’s internal framework, which had been designed by Gustave Eiffel.

The 11-week project was completed in July 2009. The NPS once again reopened the monument to the public, but limited the number of visitors to 30 at a time: 10 people in the crown’s observation platform, and 10 apiece on each of the statue’s staircases. “This was a management strategy recommended by Hughes Associates to minimize exposure of visitors and NPS staff to risks while in the statue,” says Duffy. “Previous to the planned re-opening of the monument this fall, the NPS will re-evaluate how visitors are managed to maintain safety and make appropriate changes.”

Immediately following the 125th anniversary of Lady Liberty’s commemoration last October, the NPS once again shut down access to the monument to begin the next phase of fire and life safety upgrades. (Liberty Island, the nearly 15-acre [six-hectare] plot of land in New York Harbor where the statue is located, has remained open to visitors during the project. The island attracts about 3.5 million visitors a year.) Before work could begin on the next phase of life safety upgrades, NPS had to secure the funding, conduct an environmental assessment, and complete designs for new elevators and improved egress routes that didn’t compromise the structural and historical integrity of the monument. NPS anticipates the completion of all upgrades, including restroom renovations and a new HVAC system, by the end of the year.

One key element of the second-round improvements was the main elevator, which is housed in the pedestal and transports passengers to a level below the pedestal observation platform. (From there, visitors take a supplemental lift or stairs to the platform.) The problem was that the existing elevator — a freestanding glass model with no enclosure — did not meet the necessary code requirements for size. Creating a larger elevator shaft at the same location would have impacted the pedestal’s structural beams, so contractors relocated the shaft to another portion of the pedestal’s interior. The demolition of nearly 1,300 cubic feet [nearly 37 cubic meters] of concrete — a modest amount that was approved by SHPO, notes Duffy — helped make way for the new elevator core as well as two new code-compliant staircases configured around the core that lead to the observation platform. The freestanding elevator was removed.

Those new staircases include pressurization systems that bring in outside air to minimize the presence of smoke during a fire event.

“Theoretically, if the doors are closed, the pressurization prevents smoke from entering the stairs,” says Ferreira. “Pressurization systems are required for stairwells in new high-rise buildings.” The “means of egress” chapter in NFPA 101 establishes the range of provisions needed for such “smoke-proof enclosures.” For example, access to and discharge from the enclosures, as well as pressurization levels needed to keep the environment clear of smoke from a fire, must be balanced against the opening force of the enclosure doors. The code also requires emergency power to the mechanical fan system. Additionally, pressurization of high-rise exit stair enclosures is a requirement listed in the high-rise buildings chapter of NFPA 5000, Building Construction and Safety Code®.

Also underway is the development of a “supplemental lift” to transport visitors who may have mobility impairments from the main elevator’s highest level in the pedestal to the pedestal’s observation platform, as well as the replacement of the statue’s emergency elevator, which travels from the pedestal observation level to a floor level near the statue’s shoulder. Workers are also upgrading the pedestal’s fire protection systems by installing sprinkler and fire pump systems throughout the entire monument, with the exception of the helical stairs and emergency elevator landings. Ferreira says NFPA 13 and 72 were referenced during the design of these components.
 
The existing fire alarm system is also getting a boost, and now provides an array of visual and audible notifications. Initially limited to only portions of the monument, smoke detection monitoring and audible alerts will now occur throughout the structure. An updated fire command center, located at the base of the pedestal, will interface with a new smoke control system. According to NFPA 72, the fire command center, used by emergency responders, usually provides the status of detection and alarm communications systems and operator controls for the smoke control system.

Integrating such structural improvements on a grand scale is nothing new for Hughes Associates, which kept historical preservation in mind while also developing safety upgrades for the Library of Congress and National Gallery of Art in Washington, D.C. “There are many historic buildings in the U.S. that can’t meet…the code to the letter, but there are safety improvements that can be made to maintain the historic aspects of the building,” says Ferreira. “This project is probably one of the top projects I’ve worked on. We’ve allowed people to safely access the Statue of Liberty’s crown — that’s pretty important.”