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Fire safety concerns for rail rapid transit systems
Fire Safety Journal, 8 (1984/85) 3 - 7
Fire Safety Concerns for Rail Rapid Transit
3
Systems
JIM BURNETT National Transportation Safety Board, Washington, DC 20594 (U.S.A.) (Received August 2, 1983)
SUMMARY A fire within an underground rail rapid transit system, particularly in a tunnel location, poses a highly hazardous condition to passengers, transit employees and emergency response personnel. Certain considerations in the improvement o f fire safety are universal to all transit systems. A n u m b e r o f problems have been identified by the National Transportation Safety Board, an independent U.S. government accident investigation agency, as warranting immediate attention to minimize the threats posed. The Safety Board's concern was heightened by several accidents on rail rapid transit systems involving many passengers. The fact that during peak hours, a single rail rapid transit train could carry as many as 1500 to 2000passengers was not overlooked. Specifically, the Safety Board reviewed the following topical areas which may complicate fire and life safety in confined rail rapid transit tunnel locations: --transit car materials: combustibility and toxicity; -emergency tunnel ventilation; - - t u n n e l emergency evacuation considerations; -communications; -breathing equipment; -- mobility. It is hoped that the lessons learned in our accident investigations involving fire and emergency evacuations will add to the collective knowledge o f transit systems and emergency response personnel to further minimize the hazards. INTRODUCTION
In July 1980, the National Transportation Safety Board (Safety Board) convened a major public hearing on rail rapid transit (RRT) 0379-7112/84/$3.00
safety. This hearing was p r o m p t e d by a series of fires in which a number of fire safety concerns were raised. These safety problems warranted immediate consideration by the U.S. R R T industry, fire service professionals, and local, state and federal governments because the accidents posed an enormous potential for disaster. The Safety Board's alarm was heightened by the fact that during peak hours, a single R R T train could carry a "crushload" of 1500 to 2000 passengers. Under such conditions, the loss of life in an accident, fire, or other emergency could well be catastrophic. Because of this threat, the Safety Board brought together representatives of transit system management and labor, local fire departments, national fire safety organizations and state and federal agencies to explore how the fire safety record of rail rapid transit systems in the United States could best be improved. Fire safety is critical in R R T systems because flame spread, smoke emission and toxic fumes in the limited confines of subway tunnels can be extremely hazardous and particularly difficult to control. One noted fire official described the New York subway system as " . . . a long narrow cellar filled with thousands of people, live electrical equipment, and moving vehicles". Still another fire official termed the San Francisco subway system " . . . a skyscraper without windows, lying on its side". In many respects the comparisons are accurate, yet, they are not entirely adequate to convey an understanding of the many varied problems which complicate fire and life safety in confined R R T tunnel locations. TRANSIT CAR MATERIALS: COMBUSTIBILITY AND TOXICITY
One major area of conern developed through accident investigations, continuing evaluation © Elsevier Sequoia/Printed in The Netherlands
o f R R T s a f e t y , and the public hearing was t h e i n t r o d u c t i o n i n t o transit s y s t e m s o f n e w synthetic materials w h i c h are lightweight, attractive a n d c o n v e n i e n t t o use. As t h e s e m a t e r i a l s b e c a m e available, R R T s y s t e m s used t h e m in transit car seat cushions, m o l d e d parts, wall paneling, electrical insulation and o t h e r car p a r t s b e c a u s e o f weight, c o m f o r t , c o n v e n i e n c e a n d aesthetics. U n f o r t u n a t e l y , their characteristic c o m b u s t i b i l i t y , s m o k e - g e n e r a t i o n a n d t o x i c i t y w h e n e x p o s e d t o fire w e r e n o t fully e x p l o r e d . As a result, a g e n e r a t i o n o f R R T cars was designed a n d built which, w h e n exp o s e d to fire, p o s e d s u b s t a n t i a l risks t o passengers. T h e s e cars also w e r e c o s t l y t o r e t r o f i t . T h e c o n t r i b u t i o n o f such c o m b u s t i b l e interior m a t e r i a l s used to the g r o w t h o f a fire o n c e it has s t a r t e d is p r o b a b l y b e s t e x p l a i n e d b y t h e p h e n o m e n o n called " f l a s h o v e r " . T h e Fire Protection H a n d b o o k o f t h e N a t i o n a l Fire P r o t e c t i o n A s s o c i a t i o n ( N F P A ) describes the potential contribution of combustible materials in an e n c l o s e d area to r a p i d f l a m e spread: Recent full-scale room and building fire tests have shed new light on the phenomenon called "flashover". Previously, it was beheved that combustible gases, released during the early stages of a fire, collected at the ceiling level, gradually mixing with air until within the flammable range. At this point, ignition would occur, suddenly and rapidly; hence, the descriptive term flashover. It is currently held that, while this ignition of combustible gases may occur, it precedes the flashover. Flashover is now believed to be caused by thermal radiation feedback from the ceiling and upper walls, which have been heated by the fire. This radiation feedback gradually heats the contents of the fire area. When all the combustibles in the space have become heated to their ignition temperatures, simultaneous ignition occurs [ 1 ]. Certainly, t h e dangers o f s y n t h e t i c m a t e r i a l s t h a t are e x p o s e d t o fire have b e e n s h o w n b y several m a j o r fires in buildings in t h e last decade. Likewise, t h e role o f s y n t h e t i c m a t e r i a l s as a f a c t o r in s p r e a d i n g fires o n rail r a p i d transit e q u i p m e n t has clearly b e e n d o c u m e n t e d , as in t h e 1 9 7 6 " C h r i s t i e F i r e " o n t h e T o r o n t o T r a n s i t C o m m i s s i o n ( T T C ) a n d t h e 1 9 7 9 fire in t h e T r a n s b a y T u b e on t h e Bay A r e a R a p i d Transit District ( B A R T ) . In b o t h o f t h e s e fires the f l a m e s p r e a d a n d s m o k e emission w e r e so r a p i d t h a t r e s p o n d i n g e m e r g e n c y service personnel w e r e u n a b l e to c o p e w i t h t h e situation. I n v e s t i g a t i o n s o f these t w o a c c i d e n t s led t o c o n c l u s i o n s t h a t seat c u s h i o n m a t e r i a l s - -
s t y r e n e b u t a d i e n e on t h e T T C train a n d p o l y u r e t h a n e on the B A R T train - - w e r e r e s p o n sible f o r t h e r a t e o f g r o w t h o f t h e fires. A S t a t e of California Public Utilities C o m m i s sion r e p r e s e n t a t i v e testified at t h e S a f e t y B o a r d ' s hearing t h a t : .tests [on BART cars] demonstrated that in the event that the car floor is breached by fire near a seat, there would be flames at the ceiling within 3 or 4 minutes and full involvement (flashover) would occur no more than a further 2 minutes. It would be imperative to evacuate people on the incident car and adjacent cars before flashover occurred. Such a fire wouls also produce enormous quantities of black, toxic smoke [ 2 ]. A l t h o u g h t h e S a f e t y Board has been conc e r n e d w i t h m a t e r i a l s u s e d in t h e i n t e r i o r o f transit cars, t h e r e also are d a n g e r areas whereever h e a v y electrical wiring is f o u n d . M a n y o f t h e materials u s e d t o c o a t electrical wiring m a y p o s e t o x i c i t y hazards. F o r e x a m p l e , electrical arcing b e t w e e n wires c o a t e d w i t h p o l y vinyl chloride (PVC) i n s u l a t i o n can p r o d u c e s u b s t a n t i a l a n d lethal q u a n t i t i e s of p h o s g e n e gas a n d h y d r o g e n chloride, a c c o r d i n g t o tests c o n d u c t e d b y the U.S. N a t i o n a l B u r e a u o f S t a n d a r d s . Since m o s t transit car fires are electrical - - p e r h a p s as m a n y as 90% - - a n d 65% o f t r a n s i t fires originate u n d e r t h e f l o o r o f t h e car, w h e r e the c a r ' s h e a v y d u t y electrical e q u i p m e n t is l o c a t e d , p a r t i c u l a r a t t e n t i o n m u s t b e given t o this area. C e r t a i n l y , t h e transit i n d u s t r y in t h e U n i t e d States n o w is a b u n d a n t l y a w a r e t h a t p o l y u r e t h a n e a n d o t h e r s y n t h e t i c p r o d u c t s are s u b s t a n t i a l risks in t h e e v e n t o f a fire. I n d e e d , t h e Chief S u r g e o n o f t h e B o a r d o f Police a n d Fire S u r g e o n s f o r t h e District o f C o l u m b i a testified at t h e S a f e t y B o a r d ' s h e a r i n g t h a t : Plastic and synthetic materials should not be used in subway car construction because of the "flashover" potential and rapid buildup of toxic gases in a fire situation. T h e B A R T fire o f J a n u a r y 17, 1 9 7 9 , in w h i c h b u r n i n g p o l y u r e t h a n e seat c u s h i o n s p r o d u c e d a dense, b l a c k s m o k e a n d h y d r o g e n c y a n i d e gas, killed a fire fighter. His d e a t h was a t t r i b u t e d t o s m o k e i n h a l a t i o n and c y a n i d e poisoning. Historically, fire d e a t h s d u e t o s m o k e inhalation h a v e b e e n a t t r i b u t e d p r i m a r i l y t o carbon monoxide. Recently, the Foundation for Fire S a f e t y , a n o n p r o f i t o r g a n i z a t i o n , ann o u n c e d t h a t it will s t u d y t h e role o f o t h e r
toxic products emitted by a wide variety of synthetic, plastic and other materials. Perhaps this effort will shed further light on precisely what incapacitates and kills people in fires, particularly in subway tunnels.
EMERGENCY TUNNEL VENTILATION
It became apparent from the Safety Board's hearing that fire service officials consider emergency ventilation to be a fundamental safeguard in raft rapid transit tunnels. Emergency ventilation systems must be capable o f rapidly removing smoke and toxic gases. Unfortunately, emergency ventilation systems in some transit systems were designed prior to the introduction of new synthetic materials into transit cars. The result has been that under actual fire conditions the emergency ventilation systems were unable to handle the large amounts of smoke emitted from burning synthetic materials. This has made passenger escape and tunnel access by fire fighters difficult in major transit fires. Additionally, emergency procedures for control of air flow must be carefully preplanned. In several fires, RRT ventilation operations were not coordinated effectively with fire service personnel and when fire fighters arrived to combat the fire, they were driven back when smoke was drawn in the wrong direction. Perhaps one way to solve such problems is to test emergency ventilation systems with smoke generators on a periodic basis to insure that the systems function effectively under a worse-case fire and smoke scenario.
TUNNELEVACUATIONS
As a general rule, it was found that underground transit systems plan to move any disabled train to the nearest station to disembark its passengers. Emergency evacuation of passengers on f o o t in a tunnel is a last resort. Recent accidents have demonstrated that conditions may make it impossible to move a train to the nearest station or transfer passengers to another train. Obviously, evacuations in tunnel conditions are very difficult. Transit tunnels were n o t being designed to provide adequate means o f escape for the large number
of passengers which may be involved in a fire emergency. The Safety Board's hearing showed that retrofit of present underground transit tunnels would be difficult or even impossible. However, there are some corrective actions that can be taken to improve underground tunnel evacuations. For example, most transit systems are designed with a walkway along one wall of the tunnel. Tunnel evacuations m a y be necessary onto the walkway, rather than the track bed where the electrified third rail poses a serious safety hazard in evacuations. Study of walkways in transit systems reveals that pipes or other equipment often protrude from the tunnel wall, reducing the ease of access on the walkway. Engineering changes to remove such impediments could significantly improve the speed at which passengers could get away from disabled trains by using walkways. Normal lighting in transit tunnels is generally adequate. Most lighting is located near the top of the tunnel. However, in the event of a fire, with moderate to heavy accumulations of smoke, visibility can be reduced substantially. In the BART accident, for example, passengers said the smoke was so dense that they could not see the walkway and tunnel lighting was obliterated. The placement of tunnel lighting should be reviewed for maxim u m effectiveness in emergency conditions. Once passengers must exit transit cars in an emergency, the need for directions and signs indicating exits becomes critical. Everyone is familiar with emergency exit signs in public buildings which indicate emergency exit routes. The Safety Board determined in its hearing that all rail rapid transit systems use signs, located at intervals throughout underground tunnels, to give directions. These signs, called "chain markers", generally have arrows and numbers to indicate direction and distance in feet to the nearest station and/or emergency exits in either direction. Unfortunately, transit systems have no standard criteria for these chain markers. They vary from one transit system to another, and in some cases within a single system. Differences include the a m o u n t of information, the way it is displayed, marker height, and distance between markers. For example, some transit systems include the word " e x i t " on chain markers; some do not. Some chain
markers do not make it clear that the numbers displayed represent the distances in feet to the nearest exits. Certainly, these types of chain markers probably are understood by persons who are familiar with them, but the Safety Board is concerned that they could be meaningless to passengers having to evacuate a tunnel on foot. As a result of the Safety Board's study of this problem at least one transit system has reviewed the effectiveness of its chain markers and has considered new markers -- possibly " with highly reflective material for improved visibility -- that will stand out from the tunnel wall.
Emergency Evacuation Times All transit systems have established procedures for emergency evacuation. Generally, these procedures include notification o f fire and emergency service organizations, shutdown and restoration of third rail power, operation of emergency ventilation systems, evacuation of passengers, on-the-scene coordination with emergency service personnel, and actions to be taken by transit m o t o r m e n and other employees. A major concer developed at the Safety Board's hearing was the time it takes to evacuate all passengers from a fully loaded transit train. It was found that this information is unavailable until a real fire or other emergency develops. Such experiences in the United States have shown that it takes 50 - 90 min to evacuate underground transit trains in an emergency. If fire and toxin smoke levels are contained, the evacuation times presented no difficulties. However, new transit cars emit so much toxic smoke when burning that evacuation times of 50 - 90 min may not be acceptable. Evacuation can be further delayed by failures of emergency procedures. Usually, this is the result of insufficient testing of the emergency procedures under simulated conditions to verify the effectiveness of the procedures before an actual fire incident or accident occurs. As a result of the Safety Board's concern, several transit properties have made concerted efforts to improve their emergency procedures and their pretraining for emergencies. This has included monitoring by observers and follow-up critiques by participants and observers. Even though there is still much work to do in improving evacuation times in the event of an
emergency, the Safety Board has been pleased by these efforts.
OTHER EMERGENCY CONCERNS The Safety Board has found that tunnel fires or smoke incidents also pose serious problems with communications, breathing apparatus and the mobility of fire and rescue forces.
Communications In a tunnel, emergency fire and rescue efforts cannot be effective without extensive communications among fire, rescue and transit system personnel. Conventional communications normally used by fire service organizations often are ineffective in tunnels without special equipment. At the Safety Board's hearing, fire service officials said it was essential that underground tunnels be equipped with dedicated emergency communications systems and a telephone system or capability for use of portable telephones. Inadequate communications has been identified as a serious problem in many of the fires that have occurred on rail rapid transit systems. Because of this, many transit systems have acted to upgrade existing communications or to retrofit with new equipment. The Administrator of the United States Fire Administration testified that " . . . t h e English and Germans are experimenting ... at the present time with some novel approaches", to emergency communications for transit systems. I am confident that any such technological innovations will be shared worldwide.
Breathing Equipment Generally, the usefulness of fire fighters' breathing apparatus is of short duration. This equipment may not provide adequate breathing capability for the extended periods of time that can be involved in rescue operations and fighting of underground transit fires. Most fire department breathing equipment has a nominal 30-rain rating, but fire fighters in tunnel emergencies may have to travel a mile or more in heavy toxic smoke conditions. Considerable attention thus should be given to insure t h a t long-term (one-hour or more) breathing equipment is available, and that it is reliable, safe and easily maintainable.
Mobility One final area where improvements can be made is the use of specialized equipment to transport fire response personnel and their equipment to a fire. Generally, fire fighters can transport themselves and their equipment to tunnel access points, such as stations and vent openings. However, once at these locations their equipment must be off-loaded and hand~arried. If the fire is not at a location easily accessible by foot, fire fighters can be forced to spend precious time and energy simply getting to the fire. Sometimes transit trains can be used to transport fire fighters and equipment, but these trains depend on third rail electrical power. Third rail power often is shut down quickly. In addition to the delay this can cause for fire fighters, passenger evacuation and rescue of trapped and injured passengers also can be complicated. CONCLUSION
I believe that the findings of the Safety Board's hearing into railroad transit fire safety
as a result of accidents and incidents in the United States, highlight concerns that are c o m m o n to all such systems worldwide. The lessons learned from these accidents and incidents need to be shared. Many improvements can be made in the planning, design, construction, and operation of underground transit systems to minimize the "learning curve" in an actual fire emergency. I urge those persons with public responsibility for rail rapid transit safety to review the fire safety of their systems -- promptly and carefully.
REFERENCES 1 G. P. McKinnon (ed.) and K. Tower (ass. ed.), Fire Protection Handbook, NFPA, Boston, MA, 14th edn., January, 1976, Section 6, p. 89. 2 Safety Effectiveness Evaluation o f Rail Rapid Transit Safety, National Transportation Safety Board, Washington, DC, January 22, 1981, p. 18.
Fire Safety Concerns for Rail Rapid Transit
3
Systems
JIM BURNETT National Transportation Safety Board, Washington, DC 20594 (U.S.A.) (Received August 2, 1983)
SUMMARY A fire within an underground rail rapid transit system, particularly in a tunnel location, poses a highly hazardous condition to passengers, transit employees and emergency response personnel. Certain considerations in the improvement o f fire safety are universal to all transit systems. A n u m b e r o f problems have been identified by the National Transportation Safety Board, an independent U.S. government accident investigation agency, as warranting immediate attention to minimize the threats posed. The Safety Board's concern was heightened by several accidents on rail rapid transit systems involving many passengers. The fact that during peak hours, a single rail rapid transit train could carry as many as 1500 to 2000passengers was not overlooked. Specifically, the Safety Board reviewed the following topical areas which may complicate fire and life safety in confined rail rapid transit tunnel locations: --transit car materials: combustibility and toxicity; -emergency tunnel ventilation; - - t u n n e l emergency evacuation considerations; -communications; -breathing equipment; -- mobility. It is hoped that the lessons learned in our accident investigations involving fire and emergency evacuations will add to the collective knowledge o f transit systems and emergency response personnel to further minimize the hazards. INTRODUCTION
In July 1980, the National Transportation Safety Board (Safety Board) convened a major public hearing on rail rapid transit (RRT) 0379-7112/84/$3.00
safety. This hearing was p r o m p t e d by a series of fires in which a number of fire safety concerns were raised. These safety problems warranted immediate consideration by the U.S. R R T industry, fire service professionals, and local, state and federal governments because the accidents posed an enormous potential for disaster. The Safety Board's alarm was heightened by the fact that during peak hours, a single R R T train could carry a "crushload" of 1500 to 2000 passengers. Under such conditions, the loss of life in an accident, fire, or other emergency could well be catastrophic. Because of this threat, the Safety Board brought together representatives of transit system management and labor, local fire departments, national fire safety organizations and state and federal agencies to explore how the fire safety record of rail rapid transit systems in the United States could best be improved. Fire safety is critical in R R T systems because flame spread, smoke emission and toxic fumes in the limited confines of subway tunnels can be extremely hazardous and particularly difficult to control. One noted fire official described the New York subway system as " . . . a long narrow cellar filled with thousands of people, live electrical equipment, and moving vehicles". Still another fire official termed the San Francisco subway system " . . . a skyscraper without windows, lying on its side". In many respects the comparisons are accurate, yet, they are not entirely adequate to convey an understanding of the many varied problems which complicate fire and life safety in confined R R T tunnel locations. TRANSIT CAR MATERIALS: COMBUSTIBILITY AND TOXICITY
One major area of conern developed through accident investigations, continuing evaluation © Elsevier Sequoia/Printed in The Netherlands
o f R R T s a f e t y , and the public hearing was t h e i n t r o d u c t i o n i n t o transit s y s t e m s o f n e w synthetic materials w h i c h are lightweight, attractive a n d c o n v e n i e n t t o use. As t h e s e m a t e r i a l s b e c a m e available, R R T s y s t e m s used t h e m in transit car seat cushions, m o l d e d parts, wall paneling, electrical insulation and o t h e r car p a r t s b e c a u s e o f weight, c o m f o r t , c o n v e n i e n c e a n d aesthetics. U n f o r t u n a t e l y , their characteristic c o m b u s t i b i l i t y , s m o k e - g e n e r a t i o n a n d t o x i c i t y w h e n e x p o s e d t o fire w e r e n o t fully e x p l o r e d . As a result, a g e n e r a t i o n o f R R T cars was designed a n d built which, w h e n exp o s e d to fire, p o s e d s u b s t a n t i a l risks t o passengers. T h e s e cars also w e r e c o s t l y t o r e t r o f i t . T h e c o n t r i b u t i o n o f such c o m b u s t i b l e interior m a t e r i a l s used to the g r o w t h o f a fire o n c e it has s t a r t e d is p r o b a b l y b e s t e x p l a i n e d b y t h e p h e n o m e n o n called " f l a s h o v e r " . T h e Fire Protection H a n d b o o k o f t h e N a t i o n a l Fire P r o t e c t i o n A s s o c i a t i o n ( N F P A ) describes the potential contribution of combustible materials in an e n c l o s e d area to r a p i d f l a m e spread: Recent full-scale room and building fire tests have shed new light on the phenomenon called "flashover". Previously, it was beheved that combustible gases, released during the early stages of a fire, collected at the ceiling level, gradually mixing with air until within the flammable range. At this point, ignition would occur, suddenly and rapidly; hence, the descriptive term flashover. It is currently held that, while this ignition of combustible gases may occur, it precedes the flashover. Flashover is now believed to be caused by thermal radiation feedback from the ceiling and upper walls, which have been heated by the fire. This radiation feedback gradually heats the contents of the fire area. When all the combustibles in the space have become heated to their ignition temperatures, simultaneous ignition occurs [ 1 ]. Certainly, t h e dangers o f s y n t h e t i c m a t e r i a l s t h a t are e x p o s e d t o fire have b e e n s h o w n b y several m a j o r fires in buildings in t h e last decade. Likewise, t h e role o f s y n t h e t i c m a t e r i a l s as a f a c t o r in s p r e a d i n g fires o n rail r a p i d transit e q u i p m e n t has clearly b e e n d o c u m e n t e d , as in t h e 1 9 7 6 " C h r i s t i e F i r e " o n t h e T o r o n t o T r a n s i t C o m m i s s i o n ( T T C ) a n d t h e 1 9 7 9 fire in t h e T r a n s b a y T u b e on t h e Bay A r e a R a p i d Transit District ( B A R T ) . In b o t h o f t h e s e fires the f l a m e s p r e a d a n d s m o k e emission w e r e so r a p i d t h a t r e s p o n d i n g e m e r g e n c y service personnel w e r e u n a b l e to c o p e w i t h t h e situation. I n v e s t i g a t i o n s o f these t w o a c c i d e n t s led t o c o n c l u s i o n s t h a t seat c u s h i o n m a t e r i a l s - -
s t y r e n e b u t a d i e n e on t h e T T C train a n d p o l y u r e t h a n e on the B A R T train - - w e r e r e s p o n sible f o r t h e r a t e o f g r o w t h o f t h e fires. A S t a t e of California Public Utilities C o m m i s sion r e p r e s e n t a t i v e testified at t h e S a f e t y B o a r d ' s hearing t h a t : .tests [on BART cars] demonstrated that in the event that the car floor is breached by fire near a seat, there would be flames at the ceiling within 3 or 4 minutes and full involvement (flashover) would occur no more than a further 2 minutes. It would be imperative to evacuate people on the incident car and adjacent cars before flashover occurred. Such a fire wouls also produce enormous quantities of black, toxic smoke [ 2 ]. A l t h o u g h t h e S a f e t y Board has been conc e r n e d w i t h m a t e r i a l s u s e d in t h e i n t e r i o r o f transit cars, t h e r e also are d a n g e r areas whereever h e a v y electrical wiring is f o u n d . M a n y o f t h e materials u s e d t o c o a t electrical wiring m a y p o s e t o x i c i t y hazards. F o r e x a m p l e , electrical arcing b e t w e e n wires c o a t e d w i t h p o l y vinyl chloride (PVC) i n s u l a t i o n can p r o d u c e s u b s t a n t i a l a n d lethal q u a n t i t i e s of p h o s g e n e gas a n d h y d r o g e n chloride, a c c o r d i n g t o tests c o n d u c t e d b y the U.S. N a t i o n a l B u r e a u o f S t a n d a r d s . Since m o s t transit car fires are electrical - - p e r h a p s as m a n y as 90% - - a n d 65% o f t r a n s i t fires originate u n d e r t h e f l o o r o f t h e car, w h e r e the c a r ' s h e a v y d u t y electrical e q u i p m e n t is l o c a t e d , p a r t i c u l a r a t t e n t i o n m u s t b e given t o this area. C e r t a i n l y , t h e transit i n d u s t r y in t h e U n i t e d States n o w is a b u n d a n t l y a w a r e t h a t p o l y u r e t h a n e a n d o t h e r s y n t h e t i c p r o d u c t s are s u b s t a n t i a l risks in t h e e v e n t o f a fire. I n d e e d , t h e Chief S u r g e o n o f t h e B o a r d o f Police a n d Fire S u r g e o n s f o r t h e District o f C o l u m b i a testified at t h e S a f e t y B o a r d ' s h e a r i n g t h a t : Plastic and synthetic materials should not be used in subway car construction because of the "flashover" potential and rapid buildup of toxic gases in a fire situation. T h e B A R T fire o f J a n u a r y 17, 1 9 7 9 , in w h i c h b u r n i n g p o l y u r e t h a n e seat c u s h i o n s p r o d u c e d a dense, b l a c k s m o k e a n d h y d r o g e n c y a n i d e gas, killed a fire fighter. His d e a t h was a t t r i b u t e d t o s m o k e i n h a l a t i o n and c y a n i d e poisoning. Historically, fire d e a t h s d u e t o s m o k e inhalation h a v e b e e n a t t r i b u t e d p r i m a r i l y t o carbon monoxide. Recently, the Foundation for Fire S a f e t y , a n o n p r o f i t o r g a n i z a t i o n , ann o u n c e d t h a t it will s t u d y t h e role o f o t h e r
toxic products emitted by a wide variety of synthetic, plastic and other materials. Perhaps this effort will shed further light on precisely what incapacitates and kills people in fires, particularly in subway tunnels.
EMERGENCY TUNNEL VENTILATION
It became apparent from the Safety Board's hearing that fire service officials consider emergency ventilation to be a fundamental safeguard in raft rapid transit tunnels. Emergency ventilation systems must be capable o f rapidly removing smoke and toxic gases. Unfortunately, emergency ventilation systems in some transit systems were designed prior to the introduction of new synthetic materials into transit cars. The result has been that under actual fire conditions the emergency ventilation systems were unable to handle the large amounts of smoke emitted from burning synthetic materials. This has made passenger escape and tunnel access by fire fighters difficult in major transit fires. Additionally, emergency procedures for control of air flow must be carefully preplanned. In several fires, RRT ventilation operations were not coordinated effectively with fire service personnel and when fire fighters arrived to combat the fire, they were driven back when smoke was drawn in the wrong direction. Perhaps one way to solve such problems is to test emergency ventilation systems with smoke generators on a periodic basis to insure that the systems function effectively under a worse-case fire and smoke scenario.
TUNNELEVACUATIONS
As a general rule, it was found that underground transit systems plan to move any disabled train to the nearest station to disembark its passengers. Emergency evacuation of passengers on f o o t in a tunnel is a last resort. Recent accidents have demonstrated that conditions may make it impossible to move a train to the nearest station or transfer passengers to another train. Obviously, evacuations in tunnel conditions are very difficult. Transit tunnels were n o t being designed to provide adequate means o f escape for the large number
of passengers which may be involved in a fire emergency. The Safety Board's hearing showed that retrofit of present underground transit tunnels would be difficult or even impossible. However, there are some corrective actions that can be taken to improve underground tunnel evacuations. For example, most transit systems are designed with a walkway along one wall of the tunnel. Tunnel evacuations m a y be necessary onto the walkway, rather than the track bed where the electrified third rail poses a serious safety hazard in evacuations. Study of walkways in transit systems reveals that pipes or other equipment often protrude from the tunnel wall, reducing the ease of access on the walkway. Engineering changes to remove such impediments could significantly improve the speed at which passengers could get away from disabled trains by using walkways. Normal lighting in transit tunnels is generally adequate. Most lighting is located near the top of the tunnel. However, in the event of a fire, with moderate to heavy accumulations of smoke, visibility can be reduced substantially. In the BART accident, for example, passengers said the smoke was so dense that they could not see the walkway and tunnel lighting was obliterated. The placement of tunnel lighting should be reviewed for maxim u m effectiveness in emergency conditions. Once passengers must exit transit cars in an emergency, the need for directions and signs indicating exits becomes critical. Everyone is familiar with emergency exit signs in public buildings which indicate emergency exit routes. The Safety Board determined in its hearing that all rail rapid transit systems use signs, located at intervals throughout underground tunnels, to give directions. These signs, called "chain markers", generally have arrows and numbers to indicate direction and distance in feet to the nearest station and/or emergency exits in either direction. Unfortunately, transit systems have no standard criteria for these chain markers. They vary from one transit system to another, and in some cases within a single system. Differences include the a m o u n t of information, the way it is displayed, marker height, and distance between markers. For example, some transit systems include the word " e x i t " on chain markers; some do not. Some chain
markers do not make it clear that the numbers displayed represent the distances in feet to the nearest exits. Certainly, these types of chain markers probably are understood by persons who are familiar with them, but the Safety Board is concerned that they could be meaningless to passengers having to evacuate a tunnel on foot. As a result of the Safety Board's study of this problem at least one transit system has reviewed the effectiveness of its chain markers and has considered new markers -- possibly " with highly reflective material for improved visibility -- that will stand out from the tunnel wall.
Emergency Evacuation Times All transit systems have established procedures for emergency evacuation. Generally, these procedures include notification o f fire and emergency service organizations, shutdown and restoration of third rail power, operation of emergency ventilation systems, evacuation of passengers, on-the-scene coordination with emergency service personnel, and actions to be taken by transit m o t o r m e n and other employees. A major concer developed at the Safety Board's hearing was the time it takes to evacuate all passengers from a fully loaded transit train. It was found that this information is unavailable until a real fire or other emergency develops. Such experiences in the United States have shown that it takes 50 - 90 min to evacuate underground transit trains in an emergency. If fire and toxin smoke levels are contained, the evacuation times presented no difficulties. However, new transit cars emit so much toxic smoke when burning that evacuation times of 50 - 90 min may not be acceptable. Evacuation can be further delayed by failures of emergency procedures. Usually, this is the result of insufficient testing of the emergency procedures under simulated conditions to verify the effectiveness of the procedures before an actual fire incident or accident occurs. As a result of the Safety Board's concern, several transit properties have made concerted efforts to improve their emergency procedures and their pretraining for emergencies. This has included monitoring by observers and follow-up critiques by participants and observers. Even though there is still much work to do in improving evacuation times in the event of an
emergency, the Safety Board has been pleased by these efforts.
OTHER EMERGENCY CONCERNS The Safety Board has found that tunnel fires or smoke incidents also pose serious problems with communications, breathing apparatus and the mobility of fire and rescue forces.
Communications In a tunnel, emergency fire and rescue efforts cannot be effective without extensive communications among fire, rescue and transit system personnel. Conventional communications normally used by fire service organizations often are ineffective in tunnels without special equipment. At the Safety Board's hearing, fire service officials said it was essential that underground tunnels be equipped with dedicated emergency communications systems and a telephone system or capability for use of portable telephones. Inadequate communications has been identified as a serious problem in many of the fires that have occurred on rail rapid transit systems. Because of this, many transit systems have acted to upgrade existing communications or to retrofit with new equipment. The Administrator of the United States Fire Administration testified that " . . . t h e English and Germans are experimenting ... at the present time with some novel approaches", to emergency communications for transit systems. I am confident that any such technological innovations will be shared worldwide.
Breathing Equipment Generally, the usefulness of fire fighters' breathing apparatus is of short duration. This equipment may not provide adequate breathing capability for the extended periods of time that can be involved in rescue operations and fighting of underground transit fires. Most fire department breathing equipment has a nominal 30-rain rating, but fire fighters in tunnel emergencies may have to travel a mile or more in heavy toxic smoke conditions. Considerable attention thus should be given to insure t h a t long-term (one-hour or more) breathing equipment is available, and that it is reliable, safe and easily maintainable.
Mobility One final area where improvements can be made is the use of specialized equipment to transport fire response personnel and their equipment to a fire. Generally, fire fighters can transport themselves and their equipment to tunnel access points, such as stations and vent openings. However, once at these locations their equipment must be off-loaded and hand~arried. If the fire is not at a location easily accessible by foot, fire fighters can be forced to spend precious time and energy simply getting to the fire. Sometimes transit trains can be used to transport fire fighters and equipment, but these trains depend on third rail electrical power. Third rail power often is shut down quickly. In addition to the delay this can cause for fire fighters, passenger evacuation and rescue of trapped and injured passengers also can be complicated. CONCLUSION
I believe that the findings of the Safety Board's hearing into railroad transit fire safety
as a result of accidents and incidents in the United States, highlight concerns that are c o m m o n to all such systems worldwide. The lessons learned from these accidents and incidents need to be shared. Many improvements can be made in the planning, design, construction, and operation of underground transit systems to minimize the "learning curve" in an actual fire emergency. I urge those persons with public responsibility for rail rapid transit safety to review the fire safety of their systems -- promptly and carefully.
REFERENCES 1 G. P. McKinnon (ed.) and K. Tower (ass. ed.), Fire Protection Handbook, NFPA, Boston, MA, 14th edn., January, 1976, Section 6, p. 89. 2 Safety Effectiveness Evaluation o f Rail Rapid Transit Safety, National Transportation Safety Board, Washington, DC, January 22, 1981, p. 18.