a human factors approach to the effective design of evacuation systems/media/documents/subject...

1.CHEM.E. SYMPOSIUM SERIES NO. 122

A HUMAN FACTORS APPROACH TO THE EFFECTIVE DESIGN OF EVACUATION SYSTEMS

by B.P. Fi tzgerald, M.D. Green, J. Penington & A.J. Smith

WS Atk i ns Engineering Sciences Ltd.

1.0 INTRODUCTION

Offshore i n s t a l l a t i o n s by t h e i r very nature compress personnel and hazardous p1 ant i n t o a r e l a t i v e l y small volume. To ensure t h a t t h i s prox imi ty does not present an unacceptable r i s k the operating company must ensure t h a t t h e i r p lant i s re1 iab le w i th a high degree o f i n t e g r i t y , and t h a t there i s adequate protect ion f o r personnel e i t h e r t o remain i n safety o r t o evacuate should a hazardous inc ident occur. Should evacuation be necessary it should be ensured tha t i t can be accomplished safely, qu ick ly and w i th the minimum o f e f f o r t . This paper concentrates on the l a s t point, t ha t o f e f f e c t i v e evacuation, and discusses the elements t h a t must be considered i n order t o achieve t h i s aim.

2.0 PEOPLE DO NOT BEHAVE LIKE BALL-BEARINGS

I n general two c r i t i c a l questions r e l a t i n g t o evacuation must be answered:

a. Have s u f f i c i e n t evacuation systems been provided t o enable personnel t o escape an advancing hazard?

b. W i l l personnel use the evacuation system hardware properly i n order tha t the design evacuation r a t e i s met?

Thus i t i s necessary t o f i r s t ensure t h a t design aspects such as passage widths are adequate, s u f f i c i e n t l i f eboa ts are provided, they are i n su i tab le locat ions, the l ifeboats w i l l funct ion under adverse conditions, etc.. Such considerations w i l l ensure t h a t i t i s possible t o meet " target" evacuation rates. It i s then necessary t o consider the human behavioral aspects o f the problem: people do not necessarily act as b a l l -bearings moving a1 ong channel S as required and as the designer intended. It i s therefore essent ial t o consider human factors issues such as the po ten t ia l f o r panic, confusion, ignorance, d isor ientat ion, etc. and assess the imp1 icat ions f o r evacuation system design.

It i s important t o g ive the above factors (a) and (b) equal weight i f successful evacuation i s t o be achieved i n pract ice. Unfortunately, i n the past, hardware considerations have tended t o dominate human behavioural considerations. This i s due t o the f a c t t h a t evacuation system design has been considered as a purely engineering problem w i th engineering solut ions. Ample evidence i s now avai lable t o show t h a t t h i s approach i s misguided.


2.1 Theory and Pract ice

System designers should not be d is t racted by what we shal l c a l l the a i r 1 ine evacuation t e s t syndrome. When attempting t o estab l ish evacuation ra tes one must guard against basing tes ts on d r i l l s ca r r ied out by f i t young people, a l l very famil i a r w i th the layout and the emergency d r i l l S, dressed i n t racksu i t s and t ra iners , i n n ice warm, w e l l - l i t surroundings. It i s necessary t o be aware o f the f a c t t h a t they may have been recent ly t ra ined and spec ia l ly br iefed. The Manchester a i r d isaster i n August 1985, where 55 people l o s t t h e i r l ives through f a i l u r e t o evacuate i n a f i r e s i tuat ion, demonstrates what can happen i n rea l i t y . The In ternat ional C i v i l Aviat ion Organisation base t h e i r a i r c r a f t design accredi ta t ion upon the a b i l i t y t o evacuate an a i r c r a f t i n 90 seconds through h a l f the avai lab le ex i t s . I n t h i s incident, the time avai lab le should have been s u f f i c i e n t f o r a l l the people t o have escaped i f the performance o f the actual evacuation had matched t h a t o f the accredi ta t ion test . I n the words o f the A i r Accident Invest igat ion Branch inqu i ry repor t "as soon as smoke invades the cabin t h i s 90 seconds c r i t e r i a ceases t o have any relevance, i . e . because t h i s type o f c e r t i f i c a t i o n does not , by i n t e n t , address i t s e 7 f t o the e f f e c t s o f smoke and t o x i c / i r r i t a n t gases upon breathing d i f f i c u l t i e s , loss of v is ion, induced panic and therefore ' i r r a t i o n a l ' behaviour e.g. egress over seat -backsw.

I n - the wake o f the Manchester incident various tes ts have been ca r r ied out t o attempt t o simulate these conditions i n order t o understand why evacuation was not successful ly achieved. One o f the most noteworthy was a series o f tes ts conducted by researchers a t Cranf ie ld on behalf o f the C i v i l Av ia t ion Authori ty. I n h a l f o f these tests, the volunteers carry ing out the t e s t were offered an ext ra reward o f C5.00 i f they were among the f i r s t h a l f o f t h e i r number t o leave the a i r c r a f t .

I n each o f these tests, a f t e r an i n i t i a l per iod o f r e l a t i v e order, the s i tua t ion r a p i d l y deter iorated. The designated evacuation routes were bypassed, the a is les and e x i t doors became jammed, tempers were l o s t and near chaos resulted:

* Some volunteers walked over others, whi le some searched f o r fami ly and f r iends before t r y i n g t o escape.

* S ign i f i can t l y , a "notable number" o f volunteers were behaviourally inact ive, i e . were unable t o move.

* A number o f tes ts were abandoned as the Safety O f f i c e r considered i t t o be too dangerous t o continue.

* Two evacuations were terminated when a volunteer f e l l and would otherwise have been tramp1 ed.

The Cranf ie ld paper notes tha t many o f the volunteers f e l t t h a t they had lea rn t a great deal about how t o get out o f an a i r c r a f t i n an emergency, but tha t they had found the competit ive rush o f people a f r i gh ten ing experience. Overall the competit ive tes ts gave f a r slower times f o r t o t a l evacuation than the ordinary d r i l l S. I n te res t ing ly though, among t h e i r concl usions the researchers observed t h a t w i th a wider passageway through a bulkhead e x i t door o f 30 inches o r more, a higher r a t e o f evacuation was achieved i n the


competit ive tes ts than i n the non-competitive d r i l l s . It would however be wrong t o draw too many conclusions from t h i s ser ies o f tests. It i s by no means ce r ta in tha t t h i s competit ive urge ex is ts i n rea l emergencies and panic should not be mistaken f o r competitiveness i n t h i s form. Furthermore tes ts cannot determine what many researchers be1 ieve i s the c r i t i c a l issue, t h a t o f ge t t i ng personnel t o recognise tha t evacuation i s required. It does however demonstrate t h a t the impl icat ions o f human behaviour i n stress s i tuat ions are by no means straightforward.

2.2 What i s Panic?

The subject o f panic behaviour i s one which i s widely misunderstood, due i n no small pa r t t o popular misconceptions fue!led by the media. Almost invar iab ly i n newspaper reports the word 'panic i s used when describing the behaviour o f people running away from danger, such as a bu i ld ing on f i r e . The essent ial po in t tha t t h i s d e f i n i t i o n misses i s tha t running away i s usual ly the most sensible course o f action. There i s thus a need f o r a precise d e f i n i t i o n o f panic so tha t i s i t possible t o develop a model which w i l l explain why and when such behaviour i s l i k e l y t o occur.

A number o f attempts have been made t o provide a robust d e f i n i t i o n o f panic behaviour. A useful working d e f i n i t i o n i s provided by Smith3 as;

A fear- induced behaviour which i s non-rat ional, non-adapt i v e and non- social , which serves t o reduce the escape p o s s i b i l i t i e s o f an individua7 o r group as a whole.

This d e f i n i t i o n shows tha t panic i s not exc lus ive ly a group phenomenon but can also occur w i th ind iv iduals . It also demonstrates tha t panic can lead not only t o f l i g h t behaviour but also t o an i n a b i l i t y t o move.

Models o f human behaviour are usual ly developed from the r e s u l t s o f psycho1 ogical experiments and from conducting interviews w i th subjects who have experienced a behaviour pat tern o f in terest . However there are d i f f i c u l t i e s w i th t h i S approach f o r panic behaviour. There are obvious e th i ca l d i f f i c u l t i e s i n conducting experiments i n t o panic behaviour on human subjects, although some have been conducted (eg. Schultz4, Mintz5, and Kel ley6). I n addi t ion unfortunately most subjects who experience panic i n rea l - l i f e s i tuat ions do not survive the ordeal.

The only other major source o f information consists o f analysis o f past events. However, there i s an unfortunate tendency w i th such analysis t o a t t r i b u t e panic behaviour as the cause o f a d isaster ra the r than a consequence. An example o f t h i s i s given i n Sime w i th an inc ident t h a t occurred on 2 A p r i l 1973 a t the Lowenbraukeller i n Munich. I n t h i s accident around 3000 people were attending a concert i n a h a l l f i l l e d considerably i n excess o f i t s recommended capacity. At the end o f the concert two g i r l S were crushed t o death and a number o f other people were in jured as they made t h e i r way out o f the main e x i t .

I n subsequent repor ts i t was stated t h a t panic had l e d t o the inc ident i n view o f the f a c t tha t no ob ject ive threat t o the crowd was apparent and t h a t e ight other e x i t s were hardly used. Sime however found tha t the cause was i n f a c t the o v e r f i l l i n g o f the h a l l which meant t h a t any crowd movement resu l ted i n crushing a number o f people. This served t o provide a threatening s i tua t ion .


I n add i t i on Sime po in t s ou t t h a t no account had been taken o f t he crowds' l a c k o f knowledge o f o ther e x i t s ava i l ab le and t h a t people a t t he back o f t he crowd may we l l have been unaware o f t he pressure b u i l d i n g up a t t he f r o n t .

Notwithstanding these d i f f i c u l t i e s , several authors have attempted t o produce models o f human behaviour under extreme t h r e a t stress, most i n t he contex t of human behaviour dur ing f i r e s . Notable examples are g iven by Mawson Wood

Canter l0 and Quarante l l i ll.

The model proposed by Wood ( r e f . 9) cons is ts o f t he f o l l o w i n g f o u r stages:

l . Threat appraisal . This i s t he stage o f de tec t i on o f symptoms o f an inc ident , and the f a c t t h a t they represent a th reaten ing s i t u a t i o n . Human beings, p a r t i c u l a r l y i n groups, are decidedly r e l u c t a n t t o accept symptoms o f a p o t e n t i a l hazard as threatening. Social i n h i b i t i o n s are very s t rong a t t h i s stage, and i n d i v i d u a l s do no t want t o stand out from the crowd o r leave themselves open t o a l o s s o f face. Th is can cause a slow i n i t i a l response t o a hazard, which has obvious imp l i ca t i ons f o r the design o f evacuation systems.

Va l i da t i on of symptoms. I n i t i a l symptoms may w e l l be ambiguous t o t he ex tent t h a t t he exact nature o f t he t h r e a t i s unknown, even though i t i s apparent t h a t something i s wrong. This unce r ta in t y leads t o an attempt t o v e r i f y t he nature o f the hazard. I f an i n d i v i d u a l i s alone, some attempt may be made t o d iscover t he o r i g i n s o f a symptom, f o r example from where a smell o f smoke o r i g i na tes . Whereas the f i r s t attempts o f a group t o v a l i d a t e t he symptoms are l i k e l y t o be a group d iscuss ion o f them and t h e i r imp l ica t ions .

D e f i n i t i o n o f t h e s i t ua t i on . Having appraised and va l i da ted the symptoms, t he i nd i v i dua l o r group w i l l attempt t o s t r u c t u r e t he s i t u a t i o n based no t on l y on the symptoms bu t a l so on pe rsona l i t y , t r a i n i n g and experience. I f those invo lved have no experience o f a hazard, as i s o f t e n the case, attempts t o s t r u c t u r e t he s i t u a t i o n may be f rus t ra ted . This i n a b i l i t y w i l l l ead t o a f a i l u r e t o i n i t i a t e appropr ia te behavioural reac t ion . Thi S l a c k o f a c t i o n i n a s i t u a t i o n t h a t c l e a r l y requ i res i t f u r t h e r increases the l e v e l o f th reat , which makes i t more d i f f i c u l t t o s t ruc tu re t he s i t ua t i on , and so on. Th is s p i r a l l i n g dilemma can lead t o an in!ividual f a i l i n g t o take any a c t i o n a t a l l , known popu la r l y as f rozen w i t h fear " .

4. Eva luat ion o f a response. Having def ined the s i t u a t i o n t he re then occurs a deci sion-maki ng process concerned w i t h t he eval u a t i on o f avai l able responses. I f the response chosen does no t lead t o a lower ing o f the l e v e l o f t h r e a t then the s t ress on an i n d i v i d u a l o r group w i l l increase due t o t he f a i l u r e t o adapt. Greater e f f o r t w i l l then be invested i n the adapt ion responses and as each i s exhausted so the choice o f f u r t h e r a c t i o n w i l l become l e s s se lec t i ve . It i s i n t h i s s i t u a t i o n t h a t r a t i o n a l behaviour may de te r i o ra te i n t o non- ra t iona l , and an adapt ive response become non-adaptive - i n o the r words what may be descr ibed as panic behaviour may be experienced.


Other authors have proposed models t h a t d i f f e r i n vary ing ways from the one descr ibed above but most are agreed on the two necessary condi t ions t o occur (eg. Reference ( 5 ) , Reference ( l l ) , Jan is 12, and Turner and K i l l an 13.

These are:

( i ) A major hazard i s e i t h e r present o r perceived t o be present, and,

( i i ) The oppo r tun i t i es f o r escape d imin ish r a p i d l y .

Dr Jonathon Sime, an environmental psycho log is t whose i n t e r e s t l i e s i n t h e f i e l d o f human behaviour and b u i l d i n g safety, has focused on people's behaviour under t h r e a t o f f i r e . Sime be l ieves pan ic t o occur i n t h e cond i t ions descr ibed above. Thi S behaviour i s character ised by s e l f p reservat ion a t a1 l costs through non-social , and non-adaptive behaviour. He be1 ieves t h a t the tendency t o l i m i t in format ion t o i n d i v i d u a l s i s a misguided one which increases the l i k e l i h o o d o f panic and t h e t ime taken t o i n i t i a t e escape behaviour.

Sime's research resu l t ed i n the development o f an a f f i l i a t i v e model which p red i c t s t h a t i n a s i t u a t i o n o f p o t e n t i a l entrapment people move towards fami l i ar persons and p1 aces. Thi S con t rad i c t s t he engineer ing approach which model S human beings as non- th ink ing ob jec ts o r " b a l l -bearings enabl i n g recommendations on minimum e x i t widths t o be determined. The model assumes t h a t when people are threatened by a f i r e they w i l l t r y t o escape by moving away from the f i r e towards the nearest route . Sime's research supports t he a f f i l i a t i v e model and has revealed t h a t t he most important f ac to rs i n f l uenc ing d i r e c t i o n o f movement dur ing escape are a combination o f a person's r o l e , a f f i l i a t i v e t i e s and consequent p rox im i t y t o one e x i t o r another.

This i s i l l u s t r a t e d by Canter l5 i n h i s examination o f t he Kings Cross F i r e o f November 1987. People i n the Kings Cross Underground s t a t i o n a t t he t ime o f the f i r e were about t o cont inue t h e i r journey, i e . by l eav ing t h e s t a t i o n on a t r a i n , thereby d isp lay ing conventional and a f f i l i a t i v e behaviour. I n t h i s instance i t would have saved t h e i r l i v e s i f they had been permi t ted t o cont inue t h i s ac t ion . However, the p o l i c e o f f i c e r s present asked them t o leave the s t a t i o n by the p la t f o rm ex i t s , and so u n w i t t i n g l y l e d a number o f people t o t h e i r deaths. Examination o f t he p o s i t i o n o f the bodies showed people were overcome by flames and fumes i n pos i t i ons d i r e c t l y r e l a t i n g t o t h e i r customary journeys.

This ra i ses the issue o f the p a r t p layed by leadersh ip and a u t h o r i t y i n emergency s i t ua t i ons . A1 though i t seems t h a t London Underground s t a f f appeared t o have made attempts t o i n s t r u c t people, the evidence was t h a t no one took any not ice . I n cont ras t everyone fo l lowed the i n s t r u c t i o n s g iven t o them by p01 i c e o f f i c e r s who were t r a g i c a l l y uninformed. Thi S i S demonstrated too i n the video o f the f i r e a t Bradford C i t y Footba l l Club where people were r e l u c t a n t t o c l imb on t o the p i t c h u n t i l p o l i c e o f f i c e r s gave the d i r e c t order.


3.0 EMERGENCY DRILLS OFFSHORE - WHAT THEY TELL US

In order to appreciate how these aspects of human behaviour can be taken into account in the design of improved offshore evacuation systems, we must also recogni se how current systems actual ly operate. The eval uat i on of performance in actual incidents will provide us with some data. Also of interest, although of less direct relevance, is the wealth of experience gained from emergency dri l l S off shore.

3.1 Typical experiences

Statutory Instrument S1 1976 No. 1542 states that each installation must conduct a muster drill at least every 28 days. These drills can high1 ight potential shortcomings in an instal l ation's procedures and systems.

From the time the alarm sounds it can take anything up to ten minutes or more for personnel to muster. A further period must then be allowed for a head count, which may or may not present the desired outcome. Response times depend on the number of personnel on the installation, the size of the installation (perhaps an accommodation barge is attached), .and so on. Though difficult for the authors to substantiate, it is interesting to note that there are numerous tales of muster drills running on for an hour or more before account has been taken of all personnel.

It must be remembered that emergency drills stop short of total evacuation, even if all personnel are assembled at the lifeboats. Typical factors affecting muster times are:

A he1 icopter crew change involving key personnel can give rise to great confusion should it coincide with an evacuation alarm. These personnel may not be fully aware of what is expected of them. They are also likely to be slower to react, having possibly been off the installation for a number of weeks.

The early hours of the morning is known to be the time when personnel are likely to be slowest in responding to an alarm. Many personnel will be asleep, and generally this will include some key personnel. There is the obvious delay of personnel dressing as well as the reduction in abi l i ty to react effectively.

A high frequency of false or spurious alarms reduces the urgency of action of personnel. Thi S i S particul ary prevalent during hook-up and commissioning phases, when several false alarms may sound during the course of a day. Frequency and anticipation of drills also encourages complacent response. Some personnel, particul ary those off shift, are far more likely to await confirmation of the alarm or further information in the hope that it is all clear, so that they can stand down.

Mustering at an inappropriate location - Experience has shown that some people will muster or attempt to muster at their designated point, even if circumstances indicate that a1 ternative action i S required. Personnel less familiar with the installation may. well be unsure of a1 ternative muster points and procedures, even if they are confident in their knowledge of their designated point.


Lack o f i n fo rma t i on and/or poor q u a l i t y i n fo rma t i on through a d i s r u p t i o n i n communications o r through unavai l abi l i t y o r ill - i nformed/unfami l i a r key personnel i n many instances leads t o inappropr ia te ac t ions o r i nco r rec t i ns t ruc t i ons . Such a s i t u a t i o n i n a r e a l emergency could prove t o be disastrous.

Locat ion o f personnel can adversely a f f e c t muster response times. Obvious examples o f these would be personnel working down the legs o f a ConDeep p la t f o rm o r i n the lower pontoon spaces o f a semi- submersible.

I n j u r e d personnel and procedures f o r dea l ing w i t h them - The degree t o which personnel an t i c i pa te deal i n g w i t h i n j u r e d personnel i n an emergency s i t u a t i o n can a f f e c t t o t a l evacuation t ime almost as much as the l eve1 o f preparedness o f procedures and hardware f o r deal i ng w i t h i n j u r i e s .

Possible ac t ions t o be taken i n order t o overcome, a t l e a s t p a r t i a l l y , some o f these problems w i l l be addressed l a t e r . As i nd i ca ted above, evacuation d r i l l s o f t e n do no t t e s t the actual method o f evacuation. Only t he mustering t o evacuation po in t s i s c a r r i e d out. Hence problems l i a b l e t o be encountered i n the ac t o f evacuation by a chosen method are no t h igh l i gh ted , and so personnel are unprepared f o r overcoming them. Among many po in t s , t h i s must be one o f the important lessons from the Piper Alpha d i s a s t e r .

4.0 PIPER ALPHA - THE WORST CASE HAPPENED

It i s worth r e c a l l i n g the consequences o f the pr imary event on Piper Alpha a t 10.00 pm on 6 J u l y 1988. The esca la t ion o f the event ' l ead ing t o the massive f i r e b a l l t h a t e n ~ u l f e d the ~ l a t f o r m some twentv two minutes l a t e r has one t e r r i b l e para l l el-wi t h t he ~ h c h e s t e r a i r d i sastgr: The t ime a v a i l able should have been s u f f i c i e n t f o r a l l the personnel t o have escaped i f the performance o f the actual evacuation had matched the standard gene ra l l y expected by the o f fshore indust ry .

The main consequences o f the pr imary event were:

F i r e prevent ion systems were knocked ou t A l l alarm and Pub1 i c Address systems f a i l e d Emergency power systems were on ly p a r t i a l l y e f f e c t i v e Control Room was e f f e c t i v e l y destroyed Command s t ruc tu re was disrupted - key personnel unavai lable Emergency shutdown may not have been f u l l y e f f e c t i v e (Not proven) Some muster po in t s / l i f e b o a t s ta t i ons were rendered untenable (Not one l i f e b o a t was launched) L i f e r a f t launch systems f a i l e d o r were operated i n e f f e c t i v e l y He l icopter evacuation was made impossible due t o f i r e and smoke Evacuation routes from primary muster p o i n t s i n accommodation were impassable Communications were l o s t t o o ther nearby i n s t a l l a t i o n s and the shore.

Secondary consequences i n c l uded:

o Great d i f f i c u l t y was experienced i n evacuat ing from such he ights ( i .e. main p la t fo rm leve l s )


o Haphazard co l lec t ion and pick-up o f survivors a t sea leve l was experienced. ie . no p1 an existed, no pre-designated po in ts were established - hence no equipment such as l i f e jacke ts , rescue lights/beacons were avai lable. (This i s not a c r i t i c i s m o f the e f f o r t s o f the rescuers)

o Most rescue c r a f t were there only by CO-incidence

4.1 Survivors' Evidence

Analysis o f the evidence o f the survivors who took the stand a t the Pub1 i c Inqui ry before Lord Cullen 16, serves t o i l l u s t r a t e these po ints only too graphical ly. From days 26 t o 53 o f the Inquiry, 58 survivors f e l t able t o g ive evidence; o f whom

A number jumped into the sea:

15 from about 150 f ee t (pipe deck) 4 from 174 f oo t l eve l (He1 idecks) 1 from 84 f oo t l eve l 3 from 68 f oo t l eve l

and 5 o r so from about 20 f ee t (from hoses and a navigat ion platform).

Most descended as fo77ows:

- 25 went down a knotted rope from 68 foot l eve l t o a navigat ion p1 atform a t 20 f oo t l eve l . - 4 s l i d down a hose from a small navigat ion p la t form j u s t below the 68 foot l eve l and dropped the l a s t 20 f ee t i n t o the sea

- 1 s l i d down a second rope - 1 climbed down cables attached t o a p la t form l e g - 4 climbed down the s t ructure during a t l eas t pa r t o f t h e i r route.

Many commented on the dilemma they faced:

Some 30 o r so reported being i n the ga l ley and/or the accommodation block a t some point fo l lowing the f i r s t explosion. At l eas t s i x s p e c i f i c a l l y reported t h a t no-one was i n charge i n the ga l ley. At l eas t ten reported t r y i n g every door out o f the accommodation. Confusion, l ack o f information and a growing sense o f "panic" was reported by many. At l eas t three instances o f personnel being "frozen by fear" were reported, o f whom two were persuaded i n t o act ion by others.

O f 20 who reported shel ter ing i n the "Whitehouse", 15 jumped from the pipedeck and 4 s l i d down a hose as mentioned above.

Their eventual rescue was reported as fol lows:

21 were picked up by f a s t rescue c r a f t (FRC) from the p la t form without going i n t o the sea About 9 were picked up by FRC whi le i n the sea holding onto p la t form legs 17 were picked up by FRC from open water 6 were picked up from the sea by the support vessel, Maersk Logger 5 were picked up from the sea by the standby boat, S i l v e r P i t .


T h e i r reported use o f 7 i f e saving equipment was:

Hal f a dozen o r more d i d not have on l i f e jackets Most d i d not have on survival su i t s Two who d i d have on survival su i t s reported d i f f i c u l t y i n the water due t o hoods f i l l i n g w i th water and p u l l i n g them down Only one surv ivor who gave evidence ac tua l l y managed t o get i n t o a l i f e r a f t launched from the platform, and tha t was a f t e r jumping i n t o the sea and coming across i t by chance.

Also w i th regard t o evacuation planning, i n addi t ion t o t h e i r considered comments, some evidence by survivors i s p a r t i c u l a r l y worthy o f note:

Day 26, P61D

Day 27, P98F

Day 28, P113A

Day 28, P117D

Day 31, P24C

Day 32, P76C

Day 33, P75D

Day 35, PlOA

Day 35, P40C

Day 36, P28B

Day 37, P7B

Day 37, P31B

Day 37, P78F

"What seemed t o be l i t t l e things made a b i g d i f ference t h a t night." The d iv ing supervisor had no communications fo l lowing i n i t i a l explosion, so he had no ins t ruc t ions as t o best route t o muster stat ions. (He decided on h i s own i n i t i a t i v e ) . One man t i e d the Knotted Rope ( the s ing le most successful i tem used f o r evacuation t h a t n ight ) t o a handrai l . The witness thought t h i s was not necessary, but had no time t o argue. The witness also observed t h a t d i f f i c u l t y was encountered i n persuading people t o go down the rope. Divers t r i e d t o use a second unused FRC on the S i 7 v e r P i t but i t f a i l e d t o s ta r t . "I was caught up i n a l l the confusion" (He was near the knotted rope). Evacuation down the knotted rope was however carr ied out i n an order ly manner. "They were r e a l l y new t o the platform, and they d i d not have a clue where t o go, and so I t o l d them t o fo l l ow me; I d i d not know where we were going t o go." "I do not ac tua l l y know where I was, ..... we were t r y i n g t o f i n d ways t o get outside o f the accommodation. . . . . .For some reason, we d e c i d y t o have a rest , t o get our thoughts together, I think.. . . "There was [a queue o f people wai t ing t o get out o f t h a t door]. I do not know how many, but there were peop1e"there on t h e i r hands and knees.. . . . .because o f the smoke. ". . .but t o muster everybody i n the Whitehouse a t t h a t pa r t i cu la r time, not knowing what the emergency was, j u s t d i d not seem feasible. (On helideck, j u s t before the mushroom cloud o f flames erupted) "We were j u s t so r t o f wa! k ing about. We a l l d i d it. There was nothing else l e f t . ( I n the cinema when the f i r s t explosion happened) "There was a b i t of a panic. People s tar ted making t o the door t o get out. I got out, went t o my cabin, put on some warm clothes and a l i f e jacket." "A f te r the i n i t i a1 explosion most people were concerned about t h e i r f r iends and what was happening t o them." People were moving i n a crowd w i t h i n the accommodation, and t r y i n g the e x i t doors.


Day 37, P79G "You normal ly wa i t f o r in format ion from whoever i s i n charge, ....... nobody t o l d us anything.

Day 40, P118G ( I n the g a l l e y area) "Everyone was pushing.. . .wanted t o know what t o do."

This evidence demonstrates a number o f t he concepts o f human behaviour i d e n t i f i e d i n previous research. Everyone was aware o f t he ex is tence o f a l i fe - th rea ten ing s i t u a t i o n and, due t o the r a p i d esca la t ion o f t he inc ident , t he oppo r tun i t i es t o escape were r a p i d l y d imin ish ing. It has been i l l u s t r a t e d by the surv ivors statements t h a t confusion resu l t ed and indeed panic behaviour was experienced (a number o f people were f rozen w i t h fear, f o r example). I n some cases people adopted normal behaviour i .e. they queued t o ge t ou t o f a door and people were moving towards the e x i t doors w i t h which they were f a m i l i a r . Also many repor ted l ook ing f o r t h e i r "groupH o f f r i e n d s and workmates. I n t h i s respect i t can be sa id t h a t non-adaptive and a f f i l i a t i v e behaviour was experienced. It i s c l e a r t h a t t h i s behaviour was due t o l a c k o f in format ion ava i l ab le about the i nc iden t and a l a c k o f any i n s t r u c t i o n s o r i nd i ca t i ons regarding safe evacuation routes, coupled w i t h t he r a p i d l y growing need t o evacuate. These are the very cond i t ions under which the research discussed i n Sect ion 2 above suggests t h a t non-adaptive behaviour w i l l s t a r t t o occur.

Furthermore, i t was demonstrated t h a t people needed and sought leadersh ip and gu'idance and d i d no t rece ive it. The order t o abandon the p la t f o rm was never given . It i s a lso worthy o f note t h a t several o f the d i ve rs observed t h a t they were able t o con t r i bu te s i g n i f i c a n t l y t o the pick-up and handl ing o f i n j u r e d personnel on the Silver P i t . They f e l t t h a t t h e i r more r i g i d command s t ruc ture , arranged almost on m i l i t a r y l i nes , stood up b e t t e r i n the h i g h l y stressed s i t u a t i o n than the l ess formal company emergency response s t ruc tu re .

4.2 Post-Pi per evacuation proposal S

A number o f hardware so lu t ions t o the evacuation problems encountered on Piper Alpha have been proposed since the d isas ter , some o f which were suggested by the surv ivors themselves. The main proposal S are l i s t e d here; some o f which were already a v a i l able on the market, if no t i n use elsewhere.

The use o f the f o l l ow ing has been wide ly discussed:-

- Smoke hoods / Personal emergency r e s p i r a t o r s - Safe havens - Protected walkways t o l i f e b o a t s - Escape chutes - Personal l i f e l ines / con t ro l l e d descent devices - Scramble nets, ropes e tc . - F r e e - f a l l l i f e b o a t s (40 t o 60 seater) - Personal su rv i va l packs

These items have been suggested i n add i t i on t o the o ther measures being discussed and implemented w i t h a view t o f i r e m i t i g a t i o n and hydrocarbon re1 ease reduct ion. Measures such as sub-sea i s o l a t i o n systems, p1 a t fo rm edge and sp l ash-zone emergency shutdown valves, increased f i r e wa l l p r o t e c t ion, etc. are bound t o i n f l uence both t he p o t e n t i a l scale o f any i nc iden t and the oppor tun i ty f o r personnel t o escape.


But these are on l y the hardware so lu t ions . How can we r e l a t e the human fac to rs issues i d e n t i f i e d above t o t h e i r e f f e c t i v e implementation?

5.0 HUMAN FACTORS ISSUES THAT MUST BE CONSIDERED

As discussed i n Sect ion 4.1 above, the experiences o f t h e surv ivors amply demonstrate t he need f o r in format ion discussed by Sime '-l4. The importance o f t he p rov i s i on o f in format ion dur ing emergencies cannot, i n the opinion o f t he authors, be stressed too h igh ly . The urgency o f t he response o f personnel, and the e f fec t iveness o f t h e i r response i s d i r e c t l y rel 'ated t o the q u a l i t y and amount o f in format ion w i t h which they are suppl ied. Hence great e f f o r t should be expended t o ensure t h a t in format ion systems w i l l continue t o f unc t i on throughout any p o t e n t i a l inc ident .

There i s a l so a c l e a r need i n any th rea t s t ress s i t u a t i o n f o r a f a m i l i a r and a u t h o r i t a t i v e command s t ruc ture . The case o f t he Policemen i n t he Kings Cross f i r e , and the experience o f the d i ve rs on the Silver P i t again are ample demonstration o f t h i s .

Experience has shown t h a t t r a i n i n g o f personnel t o deal w i t h emergency s i t ua t i ons , and the var ious permutations t h a t can occur, d rama t i ca l l y improves t h e i r capabi l i t y t o respond e f f e c t i v e l y . This i s p a r t i c u l a r l y important f o r key personnel bu t i s a lso requ i red f o r a l l those involved. As previously mentioned, the shock o f seeing and having t o deal w i t h i n j u r e d personnel can have an adverse a f f e c t on the response capabi l i t y o f i n d i v i d u a l S. Emergency d r i l l s t he re fo re must take account o f t h i s .

The suggestions be1 ow are based upon these needs f o r i n fo rma t i on and command. The former includes d i r e c t vocal systems and a l so p i c t o r i a l , v i sua l and w r i t t e n guidance systems. However the suggestions f o r means o f command are necessar i l y general i n nature. This l i s t i n g i s n o t intended t o g i ve a complete s o l u t i o n and may seem ra the r pat. These a re s imply some o f t he key po in t s t h a t should be taken i n t o account i n any human behavioural and ergonomic assessment o f a design.

Human Behaviour Issues

* Prov is ion o f in format ion about t he i n c i d e n t upon which escape ac t ions can be based.

* Clear d e f i n i t i o n o f command s t ruc tu re so t h a t no mat ter who i s removed i t i s always c l e a r who w i l l s tep i n t o t he breach.

* Strong leadersh ip and guidance.

* Clear d e f i n i t i o n s o f ac t ions i n event o f alarms and o f a l t e r n a t i v e ac t ions i f no alarms. (Simple summary cards t o be included i n surv iva l packs.)

* Fear o f use / re t icence t o use w i l l i n f l uence the e f fec t iveness o f chutes, con t ro l l ed descent devices e t c . The number o f chutes provided must consider t h i s . Strong leadersh ip w i l l ease the s i t ua t i on , as has been shown people tend t o do e x a c t l y what they are t o l d under emergencies.


* Adequate emergency t r a i n i n g .

* D r i l l s t o be a t non-f ixed t imes and w i t h v a r i a t i o n o f inc ident , evacuation methods, etc. Key personnel t r a i n i n g t o inc lude t a b l e t op exercises. I f p rac t i cab le c a r r y out annual f u l l t e s t o f evacuation t o completion.

* The i nc lus ion o f " i n j u red " personnel, blocked routes, unava i lab le muster points, communication d i s rup t i ons e tc . i n t he d r i l l . Possibly w i t h donning o f smoke hoods.

Other phys ica l o r ergonomic issues need t o be considered i n t he hardware design. These obviously inc lude the avoidance o f smoke ingress t o safe havens, accommodation, main muster po in t s and pro tec ted evacuation wal kways. Other items t h a t should be noted are:

Ergonomics Issues

* In format ion p rov i s i on - b l a s t p ro tec ted PA systems and/or telephone systems, greater a v a i l abi l i t y o f two-way radios, perhaps i nd i v i dua l r a d i o rece ivers i n personal su rv i va l packs.

* Emergency l i g h t i n g o f proven e f fec t iveness, perhaps w i t h i l l urni nated arrows on evacuation routes.

* Width o f walkways, l i f e b o a t entrance doors e t c t o be adequate t o ensure desired f l ow ra tes .

* The ease o f use o f evacuation methods, t he number o f ac t ions requ i red f o r implementation must be minimised and simpl i f i e d . I ns t ruc t i ons must be c l e a r and concise, p re fe rab l y o f p i c t o r i a l type. (Remember t he p a i n t e r l i n e l eng th and the l i f e r a f t d r i f t i n g under t he p la t f o rm on Piper A1 pha.)

* The use o f simple diagrammatic i ns t ruc t i ons . Visual (and perhaps audible) a t t r a c t i o n t o chutes and l i f e b o a t s e t c when PAPA given.

* Test ing o f a l l alarms and evacuation system design t o meet ergonomic considerat ions.

The Piper Alpha d i sas te r has demonstrated several issues t h a t need considerat ion. There are two i n p a r t i c u l a r t h a t must be remembered. The f i r s t i s t h a t an i nc iden t can escalate very qu ick ly . I n such circumstances i t must be asked whether 60 people can r e a l l y ge t i n t o a f r e e - f a l l l i f e b o a t i n good order, and ready f o r an e f f e c t i v e launch. It i s q u i t e probable t h a t the perceived t h r e a t w i l l be too great f o r r a t i o n a l behaviour. In format ion prov is ion , r e l a t i n g t o the progress o f the inc ident , and f i r e w a l l p ro tec t i on can obviously p lay t h e i r p a r t i n reducing the perceived l e v e l o f t h a t t h rea t . It might no t be poss ib le however f o r a p r a c t i c a l design t o main ta in a s u f f i c i e n t l y low l e v e l o f t h r e a t f o r 60 i nd i v i dua l s t o muster, rece ive the order t o evacuate, board a l i feboa t and then launch it. Th is i s one area where the authors f e e l t h a t more research i s needed . t o ensure t h a t t h i s expectat ion i s no t unreal i s t i c . It may be t h a t smal ler l i f e b o a t s seat ing fewer peopl e are required.


The o ther p o i n t t h a t i s ra i sed by Piper Alpha i s a l e s s prec ise one, and i s . an extension o f the f i r s t . Perhaps i t i s s i m p l i s t i c t o pu t i t i n these terms, but the d i sas te r showed t h a t i f the f i r ewa te r pumps e t c f a i l you might on ly have about twenty minutes before a f u r t h e r s i g n i f i c a n t f a i l u r e occurs. As, t h i s i s on l y one data po in t , i t i s d i f f i c u l t t o draw any conclusion from it. Yet i t would seem prudent i n such a s i t ua t i on , t he worst case admittedly, t o expect l i t t l e more than ten minutes t o be ava i l ab le f o r evacuation.

It i s a lso worth remembering t h a t on P iper Alpha the worst case happened.

6.0 CONCLUSION

This paper has shown t h a t human behaviour pa t te rns p lay an important r o l e i n the e f fec t iveness o f evacuation systems. Reference has been made t o recent research i n t o human behaviour under t h r e a t stress, and f i nd ings r e l a t e d t o a number o f recent d isas ters have been used t o i l l u s t r a t e these concepts. Analysis o f t he P iper Alpha d i sas te r has demonstrated the need f o r such human behavioural considerat ions t o be taken i n t o account i n the design o f evacuation systems of fshore.

The engineer ing approach t o design o f these systems w i l l go some way t o ensur ing the safe operat ion and evacuation o f o f f sho re p1 atforms. However i t i s ev ident t h a t human beings do not always behave i n a l o g i c a l o r appropr iate manner. It i s no t always poss ib le t o p r e d i c t human behaviour but t h i s paper g ives some valuable ins ights . It i s the b e l i e f o f the authors t h a t i f these issues are incorporated i n t o the design o f evacuation systems, they w i l l improve evacuation s t ra teg ies and u l t i m a t e l y SAVE LIVES.

REFERENCES

1. Department of Transport, A i r Accidents I nves t i ga t i on Branch, Report on the Accident t o Boeing 737-236 ser ies 1, G-B GJL a t Manchester I n te rna t i ona l A i r p o r t on 22 August 1985. A i r c r a f t Accident Report 8/88. Her Majesty's Sta t ionary O f f i ce .

2. Muir, H., Marr ison C. & Evans, A., 1989, " A i r c r a f t evacuations: t he e f f e c t o f passenger mot iva t ion and cabin con f i gu ra t i on adjacent t o the e x i t . " C r a n f i e l d I n s t i t u t e o f Technology Appl i ed Psycho1 ogy Uni t , C i v i l Av ia t i on Au tho r i t y Paper 89019.

3. Smith, A.J., 1990, "Panic - A study o f i t s causes and the imp l i ca t i ons f o r opera t iona l procedures. "

4. Schul tz, D.P., 1966 "An Experimental Approach t o Panic Behaviour", O f f i c e o f Naval Research Contract, NONR-4808(00).

5. Mintz, A., 1951, Journal o f Abnormal Social Psychology. 44, 150-59.

6. Ke l ley , H.H. e t a l , 1963. Journal o f Experimental Social Psychology. 1, 20-56.

7. Sime, J.D., 1985 "The Concept of Panic" ed Canter, D., John Wiley and Sons.

8. Mawson, A.R., 1978 "PanicBehaviour: ARev iewand aNewHypothes isW, Procedures o f the 9 th World Congress o f Sociology, Uppsala, Sweden.


9. Wood, P.G., 1975, "The behaviour o f people i n Fires", F i r e Research Note No. 953, F i r e Research Station, UK.

10. Canter, D., 1985 "Studies o f Human Behaviour i n Fire", Bui ld ing Research Establishment Report, F i r e Research Station, U.K.

11. Quarantel l i , E. L., 1954, Am-Journal o f Sociology 60, 267-275.

12. Janis, I. L., 1971 "Stress and Frustrat ion", Harcourt, Brace, Jovanovitch, New York, U.S.A.

13. Turner, R.H. and K i l l an , L.M., 1972 "Col lect ive Behaviour", 2nd Edit ions Prent ice Hal l , U.S.A.

14. Sime, J.D., 1988 "Safety i n the B u i l t Environment". Univers i ty Press, Cambridge.

15 Canter, D.V., 1989 "Accident and In tent ion: A t t i t u d i n a l aspects o f i ndus t r i a1 safety. " Contemporary Ergonomics, ed i ted by E.D. Megaw.

16. The proceedings o f the Piper Alpha Disaster Inqui ry before Lord Cullen, Days 26 t o 53, February t o A p r i l 1989.

a human factors approach to the effective design of evacuation systems/media/documents/subject...

Documents