Building owners and managers owe a duty of care to their tenants to adequately plan for terrorist and criminal actions, mechanical failures, natural disasters and accidents, where in the past, prior to 9/11, fire was the only concern. As a result, new threats must be recognized and be prepared for all kinds of emergencies and evacuations. But what constitutes adequate care? Among the answers is the improved building evacuation.
Actually, working and living high can be make safer, not only from terrorist attacks but also fires triggered by other causes. The number of security-related steps that have been taken since the 9/11 terrorist attacks are too numerous to count. One of the preventive measures that have been put in place to address the problems of terrorism is by incorporates more security features around the space where the skyscraper is located. Such a preventive approach eliminates to a certain extent, the threat of car bombs.
The danger was borne out not only in the 9/11 attacks on the World Trade Center in 2001 but also in other high rise blazes reported in other countries that claimed lives. The evacuation of the World Trade Center complex is of particular interest because it was the biggest full-scale evacuation of people in modern times. What could we learn from the lessons of World Trade Center evacuations that could help in other fires? Evacuation preparedness activities are needed when mitigation measures have not prevented disasters or cannot prevent them.
Problems In Fighting High Rise Fires
Fortunately, deadly high-rise fires are rare in modern skyscrapers that have heat-activated sprinklers help to extinguish fire and the alarms to enable people to make their escape and get them out sooner. Some buildings even have their smoke alarms wired right to Fire Department dispatch, so firefighters are often on the scene before a blaze can swell. But in a building without sprinklers, or where sprinklers were being repaired or had been sabotaged, a healthy fire could get going fast. In the large, open-air office floors that are currently in favor, where everyone has cubicles instead of smaller rooms, a phenomenon called "flashover"—in which all the combustible material goes up at about the same time—can occur. When a high-rise fire reaches flashover, it starts lapping out the windows and it literally just climbs the floors. People trapped above the flames are then in peril.
Fighting high-rise fires is a nightmare to Fire Departments. There are several things that are unique to a raging fire in a high-rise situation. The operations are manpower intensive. Even getting firefighters to a high-rise fire can be difficult and takes longer time to reach the target floors, as there are a large number of occupants walking down the same stairwell. Study revealed that the access time for firefighters in tall building emergencies where elevators are not functioning and only stairways can be used, averages between 1 min and 2 min per floor, which, corresponds to between 1 1/2 hours and 2 hours (depending on the amount of gear and equipment carried) to reach 60th floor of a tall building. Further, the physiological impact on firefighters of climbing more than 10 to 12 floors in a tall building makes it difficult for them to immediately begin aggressive firefighting and rescue operations, which can mean the fire has a chance to burn longer and become bigger. The problem is that the bigger the fire, the hotter it gets. And in high-rise blazes where firefighters must attack from inside the building, some fires are so large that no hose can spray enough water to extinguish the flames. Adding to the trouble, water might be limited because of the internal plumbing that make hoses connected to water pipes high up in buildings sometimes lack adequate pressure. All of these things can create hazardous situations for the fire departments.
Firefighters can do remarkable things, and 343 died doing them on 9/11. But one thing they can't really do—is put out a raging fire in a high-rise blaze. They can conduct floor search and rescue, get people down the stairs, help the injured, vent smoke out of the exit stairwells, and fight smaller fires that impede evacuation. But if the stairwell(s) damaged or impassable, and that the elevator(s) not functioning, there is nothing the fire crew can do to save lives. Just have to wait until all the fuel is consumed, and that usually takes some hours.
Problems In Evacuating of High Rise Buildings
Skyscrapers have always been celebrated, admired and enjoyed by many. The risks and rewards of working and living in high-rise buildings are obvious. Skyscrapers maximize the best view and also the best real estate values. The initial knee-jerk reaction to skyscraper has faded away after the 9/11 events. But still, people would need to realize that the higher the floors, the longer it would takes to walk down the stairs in an emergency evacuation, if the elevators not functioning.
There are several things that are unique to a high-rise evacuation situation. Usually there is a large number of occupants in the building, which can make evacuation more difficult and last longer. The elevators are not to be used in fire evacuation, as it is unreliable. Not all people have the physical ability or the mobility of walking down the long flight of stairs unassisted. Stairways could be crowded with people fleeing down while the firefighters are rushing up. No matter how good the local fire brigade is - firefighters cannot put out fires or conduct search and rescue until they know there is one and have to be able to gain access to the building in question. It all takes time. All of these things suggest that there is a greater perception of risks to tall buildings. Occupants of the top stories of tall buildings, in particular to office blocks are more at risk in an emergency. Hence, one should consider how to ensure that those with a view of high living are kept safe and are able to get out of danger in the event of a extreme emergency.
Recommendations For Improved Building Evacuation
Heeding lessons of World Trade Center evacuations could help in other fires. After 9/11 events, many fire safety professionals believed that the current codes for tall building emergency egress is inadequate.
For example, current codes determining such things as adequate stairwell capacity, required number and location of exits focus on single floor evacuation or base on ''phased'' evacuation strategy rather than full building evacuation. The provisions of fire protected refuge floors are meant for fire evacuation purposes. If occupants are on the 68th floor, they don’t have to run all the way down the building to escape the fire, they can just run mid-way down to the refuge floor in the middle of the building. The idea is that the firefighters will put out fires before it can get to people within the refuge floors. However, that assumption could threaten lives as it proven in 9/11 tragedies.
New design of tall building should accommodate timely full building evacuation of occupants due to building-specific or large-scale emergencies such as widespread power outages, major earthquakes, tornadoes, hurricanes without sufficient advanced warning, fires, accidental explosions, and terrorist attacks. Building size, population, function, and iconic status should be taken into account in designing the egress system. Stairwell and exit capacity should be adequate to accommodate counter flow due to access by emergency responders. For existing tall buildings, they should be prepared for total building evacuation in the event of such emergencies arises.
The current building evacuation plans do not take the special-needs population into account because it rely so heavily on self-evacuation that the handicapped, old and the sick may have little chance of getting out on their own from tall building. Adopting a broad definition leaves no one behind, and the imperative is clear that emergency managers address the broad spectrum of disability and activity limitation issues. Hence, greater attention is needed regarding standards for improving building evacuation.
In short, improved building evacuation should include system designs that facilitate safe and rapid egress, methods, for ensuring clear and timely emergency communications to occupants, better occupant preparedness for evacuation during emergencies, and incorporation of appropriate egress technologies, which may allow all occupants an equal opportunity for evacuation and facilitate emergency response access.
Facilities For Improved Building Evacuation
The improvement of building egress features and the incorporation of appropriate new safety facilities will help to improve building evacuation:
1. The new design of tall buildings to have wider staircases, larger areas of refuge, and a staircase running the entire height of the building reserved for emergency responders only.
2. Developing of "fire-protected and structurally hardened elevators" to improve emergency response activities in tall buildings to responders and the evacuation of mobility impaired building occupants. The "fireman's switches" make elevator safe to use in the event of a blaze by giving firefighters control of them so they do not open on the floor of the fire. They also prevent members of the public using them. It would have taken firefighters much longer to get to fires on the top floors, if the elevator not functioning.
But what constitutes adequate care if, an estimated of about 20 percent of the building occupants living or working in high rise buildings would have difficulty in walking down long flight of stairs. Stairway evacuation is almost impossible - not just for people in wheelchairs, but also for people with walking difficulties, heart disease, epilepsy and so on. And even getting firefighters to a high-rise fire by running up the stairs can be difficult, since they might each carry 100 pounds of gear. The elevators might be unreliable, as elevators would not operate in a power outage situation. There have been instances of major power failures that were caused by technical faults of power supply stations, and in extreme cases of total power failures to buildings that were damaged by fire/explosions. Under such a situation, what are the "alternative means for people with mobility impairments to be safety evacuated" if, the elevators not in operations? For these reasons, there were recommendations that called for more redundancy and survivability being built into the building evacuation system.
3. The author views that, the ADA Design Requirements for Accessible Egress and the "Accessible Means of Egress" in NFPA 101, Life Safety Code, should include escape route choices for those unable to evacuate because of a disability. Apart from "stay in place and the sprinkler will save you", there should be an option for people to choose either to stay in place and wait for rescue or to be given the opportunity to self-reliance escape. Only with the provision of such choices can we say that the less fortunate are given the equal opportunity to evacuation.
4. Experts are looking into new escape systems for high-rise buildings under fire (or damaged by explosions) whose aim is to bypass impassable floors or blocked stairways. These would allow people trapped in higher elevations to escape safely to the street. That's why "high rise building internal and external evacuation devices" are being developed with intended performance to take people out in tall building emergencies where stairways and elevators are damaged.
5. The use of markings designed to identify stairwells, stair steps, final exits, floors, stairwell doors, handrails, and landings of an approved photoluminescence material, which shall be capable of remaining visible in total darkness for a period of at least eight hours after exposure to normal lighting conditions. When building lights go out during an emergency, exit path markings and signs create a high-intensity glow that light the way in complete darkness and even in smoke-filled buildings so that people can quickly and safely identify building escape routes.
6. More redundancy and survivability be built into building communication systems, fire alarms, sprinklers, smoke management systems and other "active fire protection" devices.
Egress Technologies
High-rise buildings should make use of egress technologies to provide alternative means of escape that are immune to failure of other building systems, enable more occupants from upper floors of a tall building to have a better chance of getting out fast under extreme emergencies. Such as, a universally designed evacuation system that is user-friendly, accessible and usable by the greatest number of people, regardless of their capabilities and relatively safe to use. Evacuation devices should be designed to protect users from flame, heat and smoke, and can operate even if the electrical supply to a building is lost. It should be able to deploy inside or on, the exterior walls of the building, provide escape solutions for high-rise buildings under fire (or damaged by explosions) whose aim is to bypass impassable floors or blocked stairways that allow people trapped in higher elevations to escape safely to the street.
Evacuation Devices
This article examines the functionality of a 'internal and external evacuation device' that is manufactured in conformance to its performance as “escape chute” tested by a ‘fire research institute for fire protection’ that permit evacuation from high-rise structures during an emergency.
In many ways, a "fire escape chute" system that is designed and approved for use in fire evacuation, will operate even if the electrical supply to a building is lost during a fire, provides the redundancy and survivability into the building evacuation system. This escape system can be retrofitted in structures from 2 stories upward to high-rise as a supplement to the existing egress. It can be deployed inside or on the exterior walls of the structure that allow people trapped in higher elevations to bypass impassable floors or blocked stairways when building under fire (or damaged by explosions) to escape safely to the street. When permanently installed the escape chute is ready to use within a few seconds from release. Depending of the length it enables as many as 30 people a minute out from danger or fire.
This unique chute has a 3-separate layer of specialized materials in its construction of the fire resistant chute tube that protect users from flame, heat, smoke:
Inner Layer: The inner layer is made up of two materials, Twaron is applied along the length of the chute, and Flexible Rohvyl yarn based on PVC chlorofibre is used across the chute. This hybrid fabric is extremely strong, very flexible and is also of heat resistant. The inner layer bears the load of the total chute, able to withstand approximately 10,000 kilos or a maximum load of 5,600 kilos per metre width of fabric.
Middle Layer: The centered layer is made up of a very elastic 'spun cell' - made of Lycra and Modlacrylic fibres - and can easily increase three times in size. It is this layer, comparable to an elastic knee supporter, which 'hold' the evacuee as soon as the arms and legs is pressed against the chute.
Outer Layer: The outer layer of the chute, made of flexible glass fibre, provides protection against fire, heat, and smoke, and can resist temperatures of up to 800°C. When firemen spray the chute with water, it can even be used at higher temperatures than that.
When the chutes are regularly used for drills, this means they have to be retrieved, folded out and up a lot after each use. The materials used for the construction of this unique chute are excellently suited for that purpose.
There are various types of escape chute installation. Some are stored away in containers, such as the single-entry type mounted on the rooftop, balcony or corridor, and window, allows occupants gain access to the chute on that floor and bring everyone outside. The multi-entry type allows occupants gain access to the chute at each floor where several levels can be simultaneously evacuated inside. In addition, there is a mobile version, which can be attached to the bucket of a sky lift or aerial ladder truck that is used by the fire department for height rescue.
Alternative Means Of Escape
While the idea of a chute evacuation may not be something that is very appealing to some people, it has slowly gained popularity. Given the opinion that elevators are unsafe to use for fire egress, stair travel is taxing and potentially dangerous for the aged and the disabled, evacuation via escape chutes provides the answer to make means of egress available to all people.
Today, fire escape chute is mostly customized for a specific application, for instance, in buildings, off-shores, ferries, grain silos, air-traffic control towers, rocket launching pads and giant shovels used in the mining industry. Some installation site may require minor alterations to the fabrics of the structure to accommodate the custom-designed platform for the chute installation. Most chute installations are permanently fixed in one location served as emergency exits.
The innovative applications in escape chute technologies have enabled designers and architects to have a new way of thinking in egress design to meet performance-based specifications for the provision of evacuation accessible to everyone in the built environment. One consideration for new buildings is to have the multiple escape chute installation and stairways constructed within the same structural core, thus allowing greater protection to both. The multiple chutes are installed at the center space of the stairwell. Such a building egress design for accessible means of escape offers the possibility to provide evacuation route choices for vertical exits in an enhanced stairwell enclosure, maximizes safety and usability for all people, including those people who have no ability of walking down stairs in an emergency. When fire occurs, the disabled and the severe mobility impaired will have to make their way, assist or unassisted, and take temporary refuge inside this enhanced stair enclosure while waiting for rescue. They can either choose to use the chute inside the stair enclosure that would get them to the ground floor or to be assisted by helpers down the stairs. Only with the provision of such choices can we say that the less advantaged people are given the equal opportunity for evacuation.
As the escape chute can be installed at strategic locations and at heights within the structure, provide redundancy and back-up as an alternative escape route, gives trapped individuals the option to make their escape from a building in the critical minutes before rescue services arrive.
For example, an escape chute can be retrofitted at the rooftop of row-multi-story type of buildings that have only one access/egress route, providing a means of fire escape for the building occupants. Generally, this type of multi-story buildings is not equipped with active fire protection devices. Media often reports of fire fatalities in such buildings where there was no other way out if the only egress route is cut off by fire! The row-multi-story buildings are commonly designed for shop-houses/offices and walk-up-apartments in the developing countries.
The concept of having the common use of fire escape chutes at the rooftop for new row of multi-story buildings is a very encouraging and affordable emergency escape solution. Developers and builders can make provision of common escape route at the rooftop of these buildings and provide a fire escape chute at each end of the escape route for people to get down in an emergency. By having the cost of the fire escape chutes build into the selling price for each unit of new shop house/office or walk-up-apartment by the developer, it would add less than 1 percent to the selling price in each new unit. Most importantly, this concept of sharing the fire escape chutes provides alternative escape route that gives trapped individuals the option to make their escape from the rooftop of the multi-story building in the critical minutes before rescue services arrive if the normal egress route is not passable.
The Costs For Improvements
Some of the recommendations to improve safety and building evacuation would be costly, if not impossible, for existing buildings. But according to some estimates, the improvements would add only 2 percent to 5 percent to the construction cost in new buildings. And some steps have minimal costs, such as planning and participation in evacuation drills.
Modern intelligent high-rise buildings have added many innovative facilities and new features that have increased their project cost, yet make their buildings marketable and saleable. Would a slight increase in the project cost for the improvement in security, safety and building evacuation systems make their buildings even more marketable and saleable?
Among the more sobering conclusions in the investigation report of the World Trade Center Disaster conducted by the National Institute of Standards and Technology is the estimate of how many people might have died if the buildings had been fully occupied when the planes struck: 14,000, rather than 2,749. That figure should cause everyone to recognize the value in improving the odds of surviving a major fire in a high-rise building, regardless of the fire's cause.
Conclusion
A recently released report from the National Institute of Standards and Technology on the “NIST Response to the World Trade Center Disaster” that can be viewed from their web site: http://wtc.nist.gov should be required reading for government officials who approve building codes, and also for building stakeholders. The report urged building and fire safety communities to give immediate and serious consideration to NIST recommendations in order to achieve appropriate improvements in the way buildings are designed, constructed, maintained, and used and in evacuation and emergency response procedures. NIST recommends to building owners and public officials to evaluate the safety implications of the recommendations to their existing inventory of buildings; and take the steps necessary to mitigate any unwarranted risks without waiting for changes to occur in codes, standards, and practices.
This article contributed by Escape Consult Mobiltex (S) Pte Ltd. For more information on escape chute evacuation please visit web site: www.escapeconsult.com or email to sales@escapeconsult.com
