The concept of phased evacuation has been highly used for a long time in the building of high-rise buildings. This is one of the major strategies used to ensure protection for people in high-rise buildings, especially against fire. When building a high-rise building some strategies can be used in case of danger. When designing the building it is very important to put in mind the safety of the occupants of the building and different strategies are put in place depending on the design of the house.
Phased evacuation is one of the major strategies used to put protection in place in high-rise buildings. The phase evacuation strategy is usually implemented in tall buildings and other sensitive buildings in society. The strategy “combines evacuating or relocating a portion of the occupant especially the ones in most danger while allowing occupants remote from an incident to protect-in-place.” (Jeffrey et al 2008) This means that the people who are highly endangered are the ones who are first relocated to ensure full safety. Relocation of the highly endangered people enables full utilization of the exit space provided, this is because the people who are in immediate danger are the ones who use exits.
While using this strategy it is assumed that no event is likely to affect occupants who are outside the affected area as the other occupants continue to safely evacuate the affected areas. The strategy allows occupants to flee from the danger zone safely and that is the reason it is highly used in high-rise buildings.
This kind of strategy is acceptable by International Building Code (IBC) and the conventional approach is used when constructing tall buildings. The strategy works in a way that the people on the floor where the incident takes place and the other floors surrounding that floor are removed from the floor to outside. The occupants on other floors are subjected to a ” protect in place strategy” this kind of strategy is implemented to ensure that there is enough safety for the people involved. The two strategies are combined for the people on the incident floor to move out without much distraction and at the same time reduce the time consumed in the evacuation of the people.
This strategy works well in cases of traditional fire events for instance the sprinkler-controlled fire. The reason is that high-rise buildings are designed in such a manner that a degree of flexibility, allows automatic suppression systems to work better in such buildings. Because of the design in which the high-rise buildings use they have proven to be effective in controlling huge fires that rise in these buildings. (Jeffrey et al 2008).
The strategy uses separations and other systems to be able to reduce dangers that may befall the affected and the other floors that are not affected. The phased evacuations are implemented while designing and building a high-rise building in these ways. At the same time, it is usually very important to notify the occupants distant from the event floor as well as those in the evacuation floor zones of the situation. This is because it helps in preventing any more problems that might arise if the fire continues or spreads in other areas. The occupants in the distant areas are informed of the incident and they are requested to remain in place to avoid any problems that may be caused by movements to the place of the incident.
When designing the high-rise building then the features that are critical for the provision of such a strategy are put in place. This kind of strategy is implemented whereby the people involved may be having problems when being moved because of various reasons. The reason for this is to allow the occupants to safely exit to avoid any accidents that might result.
Based on the incident of September 11 there was risk perception of the situation and at the same time, it added complexity to phased evacuation. The reason is that in most cases during disasters people involved pay no attention to reserve messages that are sent to them and they instead rush out immediately. People tend to trust more live voice messages over recorded messages. This means that when designing and building tall buildings the people involved should be taught to build in a way that provides live messages. For this to take place have an effective voice the people involved should be trained to avoid unwarranted concern when giving the message.
Based on the incident designers should therefore consider these issues because they are very important when an incident occurs. They should be put in place “as events of concern, as the needs of the owner and occupant characteristics differ from building to building.” Depending on the needs of the owner and the occupants, the building should be designed to accommodate these needs.
To have the phased evacuation in place the understanding of the building and its occupants is very important since it plays important role in ensuring that the building is in a way that the evacuation phase can be put in place. In addition, “protection measures should be put in place and the expected emergency response equipments.” (Jeffrey et al 2008) The strategy also should be put in such a manner that it equals to the ability, activity, and responsiveness of the people in the building and the potential of the staff to help in case an emergency occurs. (Siddens 32).
The reduction of clearance time for phased evacuation of the occupants in most cases is not determined because of the limited capability of response curves. To be able to reduce the time for evacuation effective response curves should be installed such that whenever an incident occurs evacuation takes place immediately in an orderly manner. To implement the alternative effectively calls for great cooperation between the occupants and the staff implementing the evacuation strategy.
The other alternative is that simultaneous evacuation can be implemented in high-rise buildings. This is because the strategy can help a lot in times of extreme events this is because it allows evacuation of occupants very fast because of the simultaneous exit process of people. This is a conclusion that was made after the September 11 incidence by the National Institute of Standards and Technology that tall buildings should be designed to accommodate timely full building evacuation such that in time of extreme events occupants can be evacuated fast through a simultaneous evacuation system. (Siddens 32).
Since the phased evacuation consumes reasonable time an alternative must be put in place. To reduce the phased evacuation time for major incidents evacuation of the non-residents including visitors and recreational vehicles must take place at least forty-eight hours earlier before the occupants are evacuated. This would allow faster and safe evacuation of the occupants, together with this, the other benefit is that it reduces the background traffic during the mandatory evacuation of the key residents. In addition, another advantage of using this alternative is that the reduction of the traffic also reduces the time needed for the occupants to exit. (Siddens 34).
During designing and building of the high-rise buildings, a performance-based engineered approach must be used to come up with the evacuation phase and carry out an analysis of the building conditions. In addition, they should analyze the possibility of having a simultaneous evacuation system in place in case of extreme conditions. This is the best approach that should be put in place when designing high-rise buildings since it ensures that efficiency is put in place.
Notification signals of the incidents and their effectiveness should be highly considered and put in place. This is because if they are not effective it is possible to hinder the process of evacuation in a coordinated manner. This may cause further problems since the occupants involved rush into exiting without clearly knowing the right direction to follow.
Safety features should be put in place in high-rise buildings such that all the people in the building are aware of the exits in case of emergency incidents taking place. For instance, features like “emergency lighting and marking of the pathways should be put in the high-rise buildings.” This is because they help the occupants and guide them in the right evacuation pathways, this helps to prevent confusion and chances of some of the occupants being injured in the process. In addition, it also helps to reduce the time of evacuation. (Tubbs et al 2007).
Jeffrey Tubbs, PE Arup and Brian Meacham, Selecting appropriate egress strategies, 2008. Web.
Siddens, Scott, “Rethinking high-rise egress, top to bottom.” Consulting-Specifying Engineer, 2008, 43, no. 1: 32-39.
Tubbs, Jeffrey, and Brian Meacham, Egress Design Solutions: A Guide to Evacuation and Crowd Management Planning Hoboken, N.J.: John Wiley & Sons Inc. 2007.