22 September, 2004

New Thoughts On Building Emergency Evacuations Via Elevators After 9/11
By James W. Fortune

T= he Problem

While it is virtually impractical to design elevator equipment to withstand bomb blasts, airplane rammings, or other catastrophic terrorist acts, modern elevator dispatching technology could be modified to make it possible to consider the use of the Building’s elevators for tenant, visitor or guest evacuations during or after such events.

E= vacuation Problems in Mega High-Rise Buildings

1. = For the past 30 years, we have been advising building occupants to use the exit stairs, not the elevators for evacuations during an “emergency”. Whil= e this strategy may be valid for a fire or an earthquake, it can be the wrong appr= oach for a bomb scare or terrorist attack, when time is of the essence in trying= to quickly evacuate the upper level tenants.

2. = The fact is that emergency access/egress stairs can become quite crowded during= a full building evacuation, particularly in high-rise buildings.

3. = Just as building tenants are trying to escape (usually down) and out of the building, emergency personnel are concurrently trying to access the same st= airs from the ground to go up. Thi= s can create incredible conflicts in traffic flows and stair usage. The upward charge of rescue person= nel can seriously impact the number of tenants that can escape, while the tenan= t bottlenecks can seriously hamper any rescue and emergency response efforts.

4. = In addition to ordering a building evacuation, emergency command personnel wil= l often try to direct evacuates to a “holding floor” and out of the emergency exit stairwells so they can be utilized by rescue personnel. Newer U.S. Building Codes now requ= ire that less than 1% of each high-rise building floor be set aside as an area = of refuge (holding area) for handicapped persons. In Hong Kong and China, = all new high-rise buildings must now have a completely vacant refuge floor located = at each 15 floor vertical segment within the office tower (20-25 floors for ho= tel or residential occupancies). = The thinking is that office tenants during an emergency, can walk in the stairw= ays up 5 floors and down 10 floors to reach a refuge floor.

5. = Wheelchair bound tenants and other physically challenged or aged people cannot be expe= cted to utilize exit stairs for evacuation.&nbs= p; Under present building codes, they are now encouraged to enter a hol= ding area located on each floor (normally adjacent to or in the building service/firefighters’ elevator lobbies) and wait for rescue personnel= and special elevator evacuations.

6. = Once the building tenants enter the emergency stairwells at an upper floor, the doors will automatically close behind them and they cannot usually exit unt= il they reach the ground level, a sky lobby or dedicated refuge floor.

7. = Stairwells can become quite crowded and tenants may hold the emergency stairwell access doors open until they can enter the stairwell. Keeping the stairwell entry doors = open may allow smoke and fire to enter and contaminate the stairwell.

8. = In a crowded stairwell, it can take one minute or longer for a building tenant= to transit one level. At = this rate it would have taken a person working on the 100^th floor in = the World Trade Center towers at le= ast 100 minutes to escape. World = Trade Center 1 (North Tower) apparently collapsed at 104 minutes after the aircra= ft impact while World Trade Center 2 (South Tower) only lasted 54 minutes, hardly sufficient time for the upper floor tenants to escape (presuming they could get past the impact floors) even during ideal conditions.

9. = Under current designs, none of the building’s elevators are normally availa= ble for automatic, emergency evacuations because they would normally have been returned to the bottom loading floor (designated level) on Phase 1 Firefigh= ters’ service and then shut down.

10. Most European countries have adopted the EN81 Code, which requires that all automatic passenger elevators return to the designated level and shut down. None of these elevators= can run during an emergency and the firefighters’ are supposed to access = the upper floors and respond to emergencies via one or more dedicated firefighters’ lifts. Th= ese special lifts can be quite small (630KG [1390 lbs] minimum size), usually cannot be used for service (goods lift) functions, (except in Asia) and could not possibly be utilized for timely tenant evacuations. Many Middle Eastern and Asian coun= tries have similar dedicated, firefighters’ lift requirements.

E= levator Emergency Operation Evolutions

Elevator installations have been continually upgraded = and installed to be able to withstand the effects of natural calamites such as typhoons, earthquakes and building fires.&= nbsp; After major, catastrophic events such as the 1973 Las Vegas MGM Grand fire, new firefighters’ operations Phase 1 (return) and Phase 2 (fire= fighters’ attendant service) have been developed and mandated in the U.S. Elevator Code. After the 1971 California, San Fernando Val= ley earthquake, new elevator seismic resistant equipment restraints, automatic shutdowns and special clearing operations were developed and are now routin= ely included in buildings located in strong earthquake zones. Similarly, the Asian market has developed special, high wind elevator operations for use in Hong Kong, Taipei and Shanghai where high-rise buildings can be subjected to hurricane (typhoon) force winds. This strong wind force sometimes results in excessive building displacements so special hoistway equipment snag guards, rope followers and slow down operations have been de= veloped to minimize the possibilities of elevator damage during such events. If the buildings sway increases pa= st preset thresholds, the tenants are advised to leave via the elevators. After the building is evacuated, t= he elevators are then run to pre-selected floors (usually outside of the hoist= /compensation and governor rope sympathetic vibration nodes) and shut down.

W= hat Do Elevators Presently Do During A Building Emergency?

1. = All modern passenger and service elevators installed in the U.S. are presently equipped with Phase 1 and Phase 2, Firefighters’ service, standby (emergency) power switching and emergency communications capabiliti= es.

2. = Firefighters’ emergency operation for automatic elevators requires that a signal, received from a floor smoke detector or other fire alarm systems, shall cause the elevator(s) to immediately return to the designated level (normally the gro= und floor) and shut down. If the designated level smoke detector is activated, the elevator(s) then return t= o an alternate level (normally the first floor located above the designated leve= l) and shut down. This emergency return operation is termed Phase 1, Firefighters’ Return Operation and can also be activated by a Phase 1 return key operated switch normally loca= ted in the main floor (designated level) lobby with a 2^nd duplicate, switch located in the building fire control (BMS) station.

Phase 1 Firefighters’ Operation was introduced in the early 1970’s. It particularly came into vogue following the Las Vegas MGM Grand fire, in order to minimize the possibility that persons riding on the elevators would be called to a fire involved flo= or and be killed (or asphyxiated) when the elevator doors automatically opened. Reportedly, about 2/3= rds of the hotel guests killed in the MGM Grand fire were on or about the elevator= s. Unfortunately, they continued to r= un on automatic operation and still responded to registered car and hall calls du= ring the fire.

3. = Phase 2 Firefighters’ Operation permits responding emergency personnel to commandeer any recalled elevator by activating a special in-car key switch and then to run it under their control until the building is cleared= or the emergency is terminated. = Phase 2 Operation gives complete control of the elevator to the on-board operator= so that he selects the destination (car call) and has door buttons that manual= ly controls the door opening and closing operations and sequences. The elevator(s) will not respond to registered hall calls under either Phase 1 or Phase 2 operating modes. Normally, Phase 2 operations are utilized to move emergency personnel and their equipment up = to fire floor staging areas and are not usually engaged for building tenant evacuations because:

a) = Each elevator would have to be run on Phase 2 independent service by an onboard, trained rescue person.

b) = The elevators cannot respond to hall calls, as these calls cannot be registered during firefighters’ emergency operation.

c) = The “rescue” elevator operator would have no way of knowing where to pick up waiting tenants to rescue, unless he was informed by other emergency personnel through the emergency communication system or via radio. Waiting handicapped persons, locat= ed in an upper floor “holding area”, are supposed to contact the buil= ding fire operations center over the emergency communications system, with their location then relayed to the “rescue” elevator operators.

d) = There is presently no way to interface individual “rescue” elevator operators located on each individual elevator into “group dispatching” or to determine which floors have been or are to be serv= ed, without group automatic operation.

e) = There is presently no accurate way of determining if the elevator machine room and hoistway has been compromised or is still intact to permit emergency elevat= or use.

f) &= nbsp; If a building power failure occurs during the emergency evacuations, the numbe= r of elevators that can run on emergency (standby) power may be severely restricted. Most U.S. building codes require at least one elevator/group to be capable of running on standby power at one t= ime.

g) = Most modern high-rise buildings now being constructed (particularly hotel and residential towers) are completely equipped with fire sprinkler systems. These applications sometimes inclu= de sprinkler heads located in the elevator pits, elevator hoistway enclosure t= ops and even the machine rooms. B= y code, the affected elevator must be stopped and electrical power removed from the hoist machine via a transfer switch before the hoistway and/or machine room sprinklers can be activated.

P= roposed Elevator Evacuation Operations (“Lifeboat” Operations)

1. = ; New high-rise buildings would be constructed with designated refuge/rescue floo= rs (one per each 15-20 floors or one per elevator zone) where the building ten= ants could be directed to congregate and wait for evacuation. Alternately, the building sky lobb= ies or interzone transfer floors (if any) could be utilized for this purpose.=

2. = ; The Phase 3, “Lifeboat”, rescue floor elevator operations would onl= y be activated if the elevators serving them were verified to be operational and electrical power to run them was available (normal or standby power).<= /o:p>

3. = ; European and Asian passenger elevators that are only designated for a 100% capacity = load and are equipped with load weighing/limiting devices would, 1) have these devices rendered inoperative during Phase 3 Operation so they could move regardless of the car load or, 2) would be required to be designed with 125= % of capacity loads, like all U.S. passenger elevators, so they could still move= if they became “over” loaded.

4. = ; CCTV cameras, smoke detectors and other appropriate detectors would provide a machine room and hoistway scan of the rescue elevators to ascertain that the lift equipment areas (hoistways and machine rooms) had not been compromised= . Each rescue elevator could even be cycled one time to and from the rescue floor without opening its doors to ascertain that the hoistway was indeed “clear” and that the elevator could operate automatically between the floors.<= /p>

5. = ; Upon receiving “all clear” operational status information, the fire command controls for the selected rescue elevator group would then be switc= hed to the “Lifeboat” evacuation mode. The elevators would then automatic= ally serve express only between the designated rescue floor and the designated (ground/exit) return floor. All other car calls an= d hall calls would be inoperative during this special (Lifeboat) evacuation servic= e.

6. = ; Most office building passenger elevator groups are capable of moving up to +25% = of the zone tenants exiting during a heavy down-peak, 5 minute period. So with all elevators operating in= the evacuation mode, and assuming an orderly passenger loading process (designa= ted emergency human “Lifeboat” monitors may be required to prevent overloading, door cycling problems and stop people from “rushing̶= 1; an arriving elevator), the complete assembled building/zone population could theoretically be emptied from the refuge floor(s) within 20 minutes or less.

C= onclusion

In this paper, I have tried to enunciate new evacuation methods that might be utilized so that the existing passenger elevators may= be used for “Lifeboat” operations during or after bomb hoaxes or terrorist attack emergencies.

The major life safety codes have continually evolved t= o make high-rise building occupants safer from conventional hazards. However, they don’t presently address the realities and threats of today’s terrorists attacks and h= ow to rapidly evacuate high-rise buildings during such events. New building tenant evacuation strategies and how to implement them are clearly needed.

While the introduction of Phase 3, Elevator Lifeboat Operations might be deemed to be controversial, it may be an idea whose time has come in light of the recent 9/11 events. It could certainly be applicable f= or use in mega high-rise buildings, which normally are equipped with sky lobbies, = and interzone transfer floors. Al= so, it should probably be considered as a mandatory requirement for all new high-r= ise residential and hotel towers and buildings that are to be equipped with designated, int= ermediate refuge floors.