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The key fact about a burning high rise building that has the SkyWalk concept incorporated in its design is that, unlike previously constructed tall buildings, fleeing occupants from above the fire floor(s) can rapidly leave the building without having to descend through the flame and smoke. The multiple, vertically spaced, stacked SkyWalk bridges connect the burning building to a generally similar companion building.
This frees the occupants from the restraint that heretofore has always forced them to be exposed to that danger, or worse, be trapped above the fire floor(s). At the same time, those occupants below the fire, but still at a high level, can exit to complete safety as rapidly as the occupants at the levels above the fire. They can now make a very rapid exit to safety, regardless of how high they are in the buildings. |
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Q: Are the SkyWalk escape bridges fireproof?
A: Fully. Additionally they function as firebreaks because of their fireproof construction, plus the fact that they enter a fireproof staging area in each building that is equipped with two firedoors.
Q: High rise buildings are flexible structures, and wind loads and other physical forces can cause random motion in each building causing elongation, contraction and even angulation of the sky-path between buildings. How does the SkyWalk bridge cope with that situation?
A: Easily. That was the fundamental problem blocking the full utilization of the basic concept of ground-to-roof, horizontal exit through the side of the building. The bridge/building junction is a unique arrangement that possesses the ability to compensate for the random motion of the buildings, yet provides unquestionable, positive captivity in each building.
Q: I have seen bridges connecting buildings together, many times. What is so unique about SkyWalk bridges? And why haven't bridges been used before for evacuation from burning buildings?
A: Good question! Bridges between adjoining structures have been used many times over the years. Office buildings to office buildings, hotels to garages, factory buildings to factory buildings, and similar combinations. But these have been at low levels, rarely more than two, three or four floors above ground level. They are intended for regular, daily people flow, building to building, according to the purpose of the enterprise.
- A single exception: the Petronas Towers, in Kuala Lumpur, Malaysia, where a single bridge connects the tower buildings at the 42nd floor (of 88 floors), supported at its center by a tall strut and ball joint combination rising from anchor points at the 29th floor level in each building. The stated purpose, according to the owners, and the government of Malaysia, is as a tourist attraction, functioning as a symbolic Gateway to the Capital city. From its design and construction, it is obvious that evacuation was not in the mind of the designer.
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| “Each bridge is designed with an independent pressurizing system, and a backup pressurizer. Electric power is redundantly supplied from each building, to both units.” |
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Q: What are some of the important details of the escape bridges?
A: They are environmentally enclosed, and constructed of materials that will not support combustion and are commonly used in fireproof construction. Each bridge is designed with an independent pressurizing system, and a backup pressurizer. Electric power is redundantly supplied from each building, to both units. The walkway is located above the utility bay, which carries redundant electric power, water, communication lines, and other utilities. Under the utility section is the main support structure.
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“It is a happy by-product of the SkyWalk concept that the time for complete evacuation is constant, and is independent of building height.” |
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- The size of the bridge depends on the maximum anticipated population of the building and the spacing between buildings, and also whether there are two or more buildings in a SkyWalk complex. To put it in clearer perspective, consider that escape bridges at every 10th floor of a burning building and its companion, approximately 150 feet of separation between buildings, and a walkway height of 9 feet above the utility bay and support structure, would enable transfer from the burning building to complete safety in 15 minutes or less. This is based on the highest building population density known to exist in New York City. Of course the bridge widths would be sized to match the intended use of a specific building, and would range from 10 to 20 feet. It is a happy by-product of the SkyWalk concept that the time for complete evacuation is constant, and is independent of building height.
Q: There has been much comment about “redundancy” in post-9/11 media coverage. Could you elaborate about that in regard to SkyWalk?
A: The subject of redundancy could literally fill a book. New York City Fire Commissioner O'Hagan's excellent treatment of fire safety in high rise buildings in his 1976 book, “High Rise/Fire and Life Safety” stated, “…fire fighters must place almost complete reliance on the building's systems and components for fire suppression.” The same is certainly true for occupants and their safe evacuation from a burning building of current design.
- Adding additional systems and components (“redundancy”) is good, but unfortunately there are some limits that come into the picture, particularly in regard to occupant evacuation. Adding additional elevators and stairways inside a stand-alone building does not guarantee that they will be operative, available, not blocked or smoke-free. Additionally, cost considerations, and they are quite significant, will inevitably limit the amount of redundancy, thus further limiting their effectiveness.
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“…the presence of SkyWalk would result in significant enough reduction in annual insurance premiums…” |
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- The “buddy system” concept of SkyWalk supplies not just some redundancy, but complete redundancy, elevators stairways, standpipes, power supply, water supply, communication services, everything necessary for rapid and safe evacuation of occupants, faster access for firefighters / rescuers and much quicker application of their services. All of this at relatively little extra cost, since the companion building is a revenue producing entity at the same time that it functions as the ultimate supplier of the redundancy function.
- Further, in the opinion of a former president of the property division of one of the largest insurance companies in the world, he can see a strong possibility that the presence of SkyWalk would result in significant enough reduction in annual insurance premiums to be a meaningful offset to the cost of the bridges.
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