Ingenuity Spring 2018

Pond Ingenuity Spring 2018 5 wind conditions. The test results yield wind loads specific to the tower design, but also provide the pressure on the exterior skin, or cladding, to support the design of those components. Pond uses all the available data to better analyze the structure and reduce the possibility of vibrations and noises due to wind. The Importance of Designing to Code A key aspect that sets towers apart is the fact they are tall, narrowly shafted, multi- faceted structures that serve as secure enclosures for highly specialized equipment. Their height drives the code specifications and regulations under which they must be designed. It is essent i a l that the des i gn team understands the numerous distinctions between Federal and local codes. The FAA interprets and applies the Codes differently, and typically more stringently, than most local jurisdictions. In fact, the FAA is their own AHJ (Authority Having Jurisdiction), meaning that typically a minimal review by the local permitting agency is completed due to the complexity of the FAA guidelines. For instance, the International Building Code has a section pertaining to Special Structures (I.e. “towers”) that allows for applying specially designed means of egress, or the way out of the building, for tall structures such as airport control towers, or a high-rise office building or condominium for example. But ATCT’s often exceed the height and area restrictions addressed in this section of the Code, creating conflicts between design needs and Code interpretations. In cases when the AHJ may not understand how this special structure functions, the designer’s challenge is to research available code narratives that either identify exclusions or identify how the code has been previously applied to find an established precedence. For example, for one of Pond’s recent projects, the overall design area of an upper level floor exceeded the allowable area suggested by the Code. A majority of the space in question was reserved for electronic equipment and building mechanical systems leaving a small area for the controllers. After discussion with the AHJ, this application of code was interpreted to mean “occupied area.” Under this interpretation, Pond was able to continue the functional design for that level, assuring that it would meet the local and AHJ’s requirements for that code. For smaller, locally operated, non-FAA involved ATCT projects, sometimes referred to as “contract towers” there is a different approach. These ATCTs are typically not tall enough to fall under the “tower” Code, and many are considered occupied shafts, where other employees in addition to the controllers work every day. One project Pond currently has underway is for an airport in southern Florida. It is a hybrid project where the airport is providing construction funding for the new facility, resulting in total local participation in the permitting and inspection process during construction. Regardless of which type or size of tower is being designed, codes are written in a way that is open to interpretation. There may be multiple design and engineering solutions that meet the requirements in a slightly different manner. It is part of Pond’s job to assess the precise meaning of the code and assure that the correct interpretation is conveyed in the design drawings – and then convey that interpretation in understandable terms. Get It Permitted Whether designing for a Federal or local project, opening a direct line of communication early on with the permitting agency’s officials is essential. These officials may include the local fire marshal, emergency responders, local zoning boards and building inspectors and others who are typically not involved in design or construction of FAA-regulated projects. Yet these same people have vested interests in the project. Initiating early contact with the site development staff and building department staff (structural, electrical, mechanical, etc.) to introduce them to the project, and then arranging follow-up meetings at multiple points of design progression, are very important and have been well received. Pond prepares for each of the meetings by developing a list of the specific code items for discussion or items changed during the latest design phase. Continuing the dialog, Pond holds follow- on meetings with the local permitting jurisdiction at key design milestones for a review of design documents, so that when permit drawings are submitted, they will pass muster. If there are any concerns or questions, these can be addressed and resolved before the project proceeds. Designing Safety into the Control Tower Workplace Throughout the design process, Pond’s in-house specialty engineers provide design expertise and conduct various constructability reviews. These thorough analyses assure that the ATCTs are built to strict specifications in design, structure and functional usability. For instance, Pond develops the electrical arc flash documents that identify safety procedures and equipment issues surrounding electrically energized components. This study results in the identification of personal protective equipment (PPE) needed to safely work on or modify energized electrical components. Pond applies its expertise to ensuring the integrity of the system and assisting the safe work practices of the personnel responsible for maintaining them. ATCTs are highly specialized structures, and Pond understands what it takes to complete these unique projects successfully. The firm has completed 75+ ATCT projects since 2005. Success is orchestrated by a tightly knit team dedicated to maintaining strict compliance with code requirements, facilitated by staying in close communication with the myriad organizations and government officials involved in each project, and driven by the ATCT’s specific design requirements. David Woods AIA, LEED AP BD+C Program Manager, Aerospace Facilities ATCTs are highly specialized structures, and Pond understands what it takes to complete these unique projects successfully.