Photo: Collin Winterbottom
Case Study: The Washington National Cathedral
August 24, 2011, is a day I will never forget. That morning I was called by my boss at the Washington, D.C., office of Wiss, Janney, Elstner Associates to join a team that would assess the damage suffered by the Washington National Cathedral during a 5.8 earthquake the day before. As I pulled up to the building, I was awestruck not only by the its sheer size (it’s currently the sixth largest cathedral in the world), but also by the intricacy and extraordinary level of craftsmanship expressed so gracefully in each of its facades. I was overcome with sadness as I saw just how much damage had occurred during the earthquake. In the days and weeks that followed, however, I also came to realize just how well the cathedral had weathered the event, and I was moved not just by the soaring spaces of this High Gothic masterpiece, but also by its resiliency in the face of natural disaster.
The Resilient Response of the Cathedral
In the Critical Infrastructure Resilience Final Report and Recommendations issued by the National Infrastructure Advisory Council of the Department of Homeland Security (DHS), “resiliency” is defined as the ability to reduce the magnitude and/or duration of disruptive events. In addition, the report notes that the effectiveness of a resilient infrastructure or enterprise depends upon its ability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event.
Although it is not likely that the potential effects of an earthquake were anticipated in the cathedral’s initial design, the base building structure itself remained intact and was able to absorb both the movement that occurred as a result of the earthquake and high winds that followed shortly thereafter as the remnants of Hurricane Irene passed through the region. Damage to the ornamental limestone pinnacles, finials, and similar elements was extensive: restoration and repairs, as well as additional measures to prevent future such failures, will take several years. Remarkably, however, no injuries were reported as a result of the event, and the building envelope was compromised at only two locations, where the roof sustained damage from building elements that fell from the towers.
Shortly after the earthquake, the cathedral was closed to the public, including daily services, and the grounds were temporarily secured until a team of architects and engineers, my team, was able to complete its work. This, of course, required cathedral administrators to adapt their operations by either discontinuing or limiting any activities that were not critically important to the day-to-day operation and maintenance of the structure itself. Initially, it was expected that the cathedral would resume activities 15 days after the earthquake, on Sept. 7, in order to allow for a series of nationally televised memorial events for the 10th anniversary of the 9/11 attacks.
However, this timeline was disrupted when the cathedral sustained another unexpected event: The mobile tower crane being used to hoist scaffolding beams and related materials to the top of the Central Tower collapsed in a heavy rainstorm. Fortunately, damage was limited primarily to concrete and asphalt paving, as well as the north elevation of the Herb Cottage, trees and landscaping in the Bishop’s Garden, the field stone wall and gate along the north edge of the Bishop’s Garden, and four vehicles. Remarkably again, only one minor injury resulted from the collapse. In the hours immediately following, the cathedral again adapted its operations and elected to cancel all activities associated with the 9/11 memorial service and found an alternative venue for the service. All work associated with temporary overhead protection and scaffolding under way at the time of the collapse on the exterior of the Cathedral was immediately halted. Evaluation of the interior vaulted ceiling and interior wall surfaces were allowed to continue, and discussion of a possible reopening in time for the upcoming holiday season began.
Due to the initial goal of safe occupancy within 15 days, the rapid recovery of the Cathedral first began to address those tasks (including making the space safe for the memorial events) determined to be of highest priority. These tasks included make-safe operations at the interior and exterior of the Cathedral, as well as assessment and documentation of all visible damage that could pose a safety risk. For the interior, WJE and Keast & Hood Co. performed hands-on sounding and removal of loose material at all locations that were accessible from a 40-foot-high rolling scaffold. At any locations where a close-range survey was unable to be performed from the scaffolding, debris netting was installed to relieve any risk from additional debris falling from overhead. Tasks at the exterior included installation of perimeter fencing, consideration for overhead protection and debris netting for high-risk elements, and visual survey of all exterior building elements to identify unstable elements that would need to be given further consideration and temporary overhead protection put into place. Also, shortly after the earthquake temporary repairs were made at the roof locations where pieces had penetrated the batten-seam lead-coated copper roof surface.
After the crane collapsed and memorial service was relocated, the critical timeline was readjusted for the public reopening on November 12 to coincide with the Consecration of the Ninth Episcopal Bishop of Washington. The recovery path was adjusted and refocused to include the investigation, disassembly, and removal of the collapsed crane. This was followed by the installation of temporary working platforms, debris netting, and scaffolding at the central tower. The team performed rope-access survey of the central and west towers to achieve a close-range visual condition assessment and sounding of the exterior walls to identify any hazardous or unstable elements along the tower shafts. Other efforts included the stabilization of the south transept turret and repairs to paving at South Road.
Key Factors in Achieving Resiliency
The DHS Report identifies three key factors in achieving resiliency which can be applied to the cathedral as well as contemporary designs: (1) robustness: the ability to maintain critical operations and functions in the face of crisis; (2) resourcefulness: the ability to skillfully prepare for, respond to, and manage a crisis or disruption as it unfolds; and (3) rapid recovery: the ability to return to and/or reconstitute normal operations as quickly and efficiently as possible after a disruption.
Robustness was reflected primarily in the cathedral’s mass-masonry structure and few slender elements, which minimized the damage. When designing contemporary buildings, robustness can be achieved on multiple levels (e.g., structural, electrical, mechanical, information systems) by creating systems that can withstand potential forces and events that are likely to occur in the area the project is to be built.
Resourcefulness was demonstrated through the rapid management response of the situation, including the assembly of experts and creation of a committee to oversee the series of events, the identification of high-priority objectives, the establishment of a critical timeline of events, the ability to adjust the timeline as events dictated, and effective communication. In present-day designs this can be addressed by establishing an emergency response committee and include a space within the project that is designed to remain intact and accessible if an event occurs. This space should include any amenities that the emergency response committee deems necessary to facilitate the management of the situation.
Rapid recovery was achieved largely due to the robustness and resourcefulness employed, allowing cathedral administrators to establish and employ successful emergency operations, to make contingency plans, and to gather the expertise needed to make critical decisions and further the recovery. When designing current projects, a designer can create an environment to encourage rapid recovery also through successful implementation of robustness and resourcefulness concepts. The idea being that if the design is robust enough to sustain minimal damage and the resources to manage the situations are available and effective, the client should be able to carry out the established actions for rapid recovery.
These ideas may be conceptually easy to understand, but it still can seem like a daunting task to employ specific measures within a project. Luckily, there are many resources available to help. DHS is a great resource that has been involved in many of the recent discussions surrounding resiliency. The DHS Science and Technology Directorate’s Infrastructure and Disaster Management Division (IDD) also engaged the National Institute of Building Sciences to convene a committee of technical experts and stakeholders in real estate development, design, and construction to develop what became the Resilience Application Project Report, published in November 2011. In addition to summarizing the overall outcome of the project highlighted within the report, it also created, for the first time, a pathway toward the development of owner’s performance requirements (OPR), which are based on quantifiable objectives for both operational and functional performance. The report also identified the targets that must be achieved in order to qualify a building or structure as “high-performance” within the broader context of the location, intended use, and anticipated service of the building or structure and the performance requirements that may be unique to that mission.
In response to this report, a beta version of the OPR model is available online at oprtool.org, where through a simple and user-friendly interface the user can input information of proposed projects. The program then employees a complex algorithm through which the information is processed and outputs up to four different comparable scenarios based on user-selected objectives. The OPR has the potential to dramatically improve the project planning process for owners and designers by allowing them to align goals and performance based on quantitative analysis of potential outcomes. Ultimately the OPR can be translated into a basis-of-design and legally enforceable set of fully integrated and comprehensive contract document drawings and specifications that, if properly implemented and enforced during construction, will deliver truly quantifiable high performance that is both functionally and operationally resilient, regardless of the scale and complexity of the project.
Although the cathedral was unable to recover within the initial 15-day timeframe, it was able to reopen to the public and regain most of its functionality in just under three months, a relatively short period: the Washington Monument, for example, remained closed to the public for nearly two years following the earthquake and reopened only recently, in May 2014.
The resiliency of the cathedral in response to these events is self-evident. However, in an age when “resiliency” and “sustainability” are tossed around as much for their buzzworthiness as they are for the organizing design principles that they represent, the real lessons that the cathedral has taught us through these events is inherent both in the robust nature of its design and the resourcefulness of those responsible for operating and maintaining this landmark — attributes that are indispensable if rapid recovery is to be a success.