While stairways are an approved route to get down for most occupants of buildings, but escape route for the disadvantaged who have either no ability or have difficulty to use stairs when lifts are considered unsafe during emergencies are often overlooked and has continue to become a moral problem.
Introduction
Currently, designated exit staircases are the minimum fire escape requirement in buildings. However, this minimum may no longer be adequate as the global population ages rapidly. Stairways are an approved route to safety for most occupants of buildings – but for the disabled and those with walking difficulties stairs can represent an insurmountable problem. Injury statistics from the U.S. Consumer Product Safety Committee (CPSC) has estimated the number of injuries related to stairs has been increasing over the last 25 years (1974 – 1998). Of this, the number of people aged 65 and above suffering from serious stair related injuries increased from about 16 percent to about 23 percent. But a more disturbing fact is revealed – most stair-related fatalities occur among people over 65 years of age.
While exit stairways in tall buildings are designed to accommodate total building evacuation, there are practical matters associated with always having to empty the total building population. In all cases of high rise evacuation, it is believed that 20% of the occupants need assistance to use stairs and the process of getting them out of the building safely may easily take hours. A difficult part of moving the severe mobility impaired people to the ground floor involves the capabilities of other occupants. Can a buddy assisting a disabled or severely mobility impaired occupant negotiate 50 flights of stairs? This can be a slow, dangerous, strenuous and painful process that could also jeopardize the lives of those rendering assistance raise a moral dilemma. This dilemma engages a ‘fairness' debate on if one person can potentially slow the progress of what could be many hundreds. Also, if there is smoke in the staircase containing fleeing occupants, poor visibility adds to their difficulty.
Fire Escape Solutions For The Disabled
According to the American Public Health Association, it encourages NFPA in its development of codes and standards, generally to utilize a "Universal Design" or inclusive design philosophy, which maximizes safety and usability for the largest range of people, including elderly persons or those of any age with disabilities. Why not provide a special designate vertical egress with multiple escape chute installation as the primary egress route for those who have difficulty or have no ability of using stairs in an enhanced staircase enclosure? Given that stair travel is taxing and potentially dangerous for the disabled and that lifts are unsafe for used in extreme emergency, the development of "Accessible Means of Escape” design, would provide a way out of a building or structure for this segment of society.
Design For Accessible Means of Escape
One consideration for new buildings to incorporate the design for accessible means of escape is to have multiple escape chute installation and stairways constructed within the same structural core, thus allowing greater protection to both. Such a building egress design offers the possibility to provide evacuation route choices for vertical exits in an enhanced staircase enclosure. It maximizes safety and usability for all people, including the elderly, non-ambulatory, handicapped peoples, and severe mobility impaired persons in an emergency.
The enhanced staircase enclosure is to be constructed in accordance to local fire code that provides protection from fire effects for evacuees so that it can be used safely for refuge and egress. The staircase enclosure include fire resistant doors to the entrance at each floor, stairs and landings at each level, multiple escape chute installation at the core structure of stair enclosure, and a fire resistant door at the level of exit discharge.
Only a minimum of 1.2 sqm area is needed at the center of the enhanced staircase enclosure for the accommodation of the multiple escape chute installation. A vertical series of small chute rooms, one for each floor is constructed at the core of the staircase enclosure. Each floor consists of doors to the chute rooms, one segment of chute at each floor inside the chute room, from the highest floor to the ground floor on the same vertical line, and a door at the level of exit discharge.
The chute tube is constructed of 2 different fabrics:
1. Outer layer – flexible elastic fabric acts as brake and operate effectively in a temperature range of from –45 degr C to +175 degr C).
2. Inner layer – Du Pont Kevlar or Enka Twaron fabric can resist temperature of up to 650 degr C. This layer supports the whole chute load and the Kevlar has the breaking strength of over 10 tons (10,000 kg).
The escape chute system need no power supply to operate, allowing it to be operational for evacuation during power outage in extreme condition. It works on the principle of gravity. Using the stress and friction vertical descend method, users regardless of body size, shape and weight, injured on stretcher and unconscious people, once inside the chute, will arrive at ground level quickly and relatively safely. The system require an extreme minimum of physical effort, the position of descend is a sitting like position. A rescuer can carry an unconscious person heavier than himself with a minimum of effort while sliding down the chute.
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.
Performance-Based Approach
Creating this egress design for means of escape accessible for all into the basic infrastructure of a building need considerable challenge where it is impracticable to comply with prescriptive provisions in the Codes. Such a design necessitates a performance-based approach. Performance-based approach allows increased design flexibility and enables engineers to provide solution to meet predefined performance criteria, in this case, “equal egress for all” in a given scenario. Such an approach would allow the incorporating of the multiple escape chute installation at the center of the enhanced staircase enclosure within the same structural core, thus allowing greater protection to both.
The accessible means of escape is a unique and integral part of the enhanced staircase development that meet an overall level of safety and thereby derive full compliance of the relevant codes of practice to prevent entry of fire and smoke into the staircase enclosure. The enclosure with the multiple-entry escape chute installation inside becomes a safe zone for refuge after a fire starts, demonstrates equivalence with prescriptive provisions and their associated fire safety objectives. In addition, the provision of accessible means of escape designed into the basic infrastructure of a building, provides evacuation accessible to everyone, meet the performance expectation of the American Public Health Association.
Conclusion
The concept of accessible evacuation for all will becoming an integral part of future building design, enhancing its functions and egress features, marketability and overall quality of life. In considering to develop better elderly-friendly buildings for the growing ageing population worldwide, and with the Disability Discrimination Act and Health & Safety legislation now in place, the provision of accessible means of escape in buildings offers worry-free solution to the disadvantaged who have difficulty or no ability of using stairs. This vertical egress design is fail-proof to get more people down, giving the disabled and the severe mobility impaired people the same ability that able-bodied people have for vertical escape, making high rise evacuation quicker and relatively safer.
This article contributed by Escape Consult Mobiltex (S) Pte Ltd, for more information visit our website at www.escapeconsult.com or email us at mobiltex@singnet.com.sg
