Safety Science 38 (2001) 157±182
www.elsevier.com/locate/ssci
Quanti®cation of behaviour for engineering
design standards and escape time calculations
D.A. Purser *, M. Bensilum
Fire Safety Engineering Centre, Building Research Establishment, Garston, Watford WD25 9XX, UK
Abstract
Occupant behaviour in ®res depends upon interactions between the occupants, the building
and the developing ®re. Although reasonable calculation models exist for the estimation of
movement time (the time required for occupants to ¯ow out of the building), time required for
behaviours taking place before the movement phase, collectively known as pre-movement
time, are poorly described and quanti®ed. A series of monitored evacuation studies and
investigations of ®re incidents in a range of di€erent building types is described. Strategies for
the application of behavioural data to design standards and escape time calculation methods
are discussed. # 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Occupant; Behaviour; Human; Evacuation; Escape; Fire engineering
1. Introduction
Fire safety depends upon the performance of a system consisting of the building
and its services, the construction materials and contents that might become involved
in a ®re, and the behaviour of the occupants. An inherently ®re safe system relies as
little as possible on the positive actions of the occupants, while an unsafe system
relies for most of its safety on the actions of the occupants. One function of the
building and its systems is therefore to protect the occupants from ®re hazards.
For scenarios involving the escape of occupants from a ®re, survival depends upon
the outcome of two parallel processes:
1.1. The developing hazard from the ®re
This incorporates ignition, ®re growth and the spread of ®re and ®re e‚uent.
These depend upon a range of variables, such as the nature and disposition of the
* Corresponding author. Tel.: +44-1923-664936; fax: +44-1923-664910.
E-mail address: purserd@bre.co.uk (D.A. Purser).
0925-7535/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0925-7535(00)00066-7
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®re load, potential ignition sources, the reaction to ®re properties of the lining
materials and contents, the height and ventilation of the compartment and the nature of the ®re e‚uent. The actions of occupants and the provision of passive containment and active smoke extraction or suppression systems also a€ect the rate of
development and extent of the hazard from a ®re.
Assessment of these processes for any particular scenario is aimed at calculating
the time when an occupant would receive an incapacitating exposure to ®re e‚uent.
1.2. The process by which occupants escape
This depends upon detection, the provision of warnings, response to warnings
(pre-movement time), occupant pro®le (such as age and physical and mental ability,
sleeping or waking, population density) subsequent pre-egress behaviour (such as
seeking information, collecting belongings, choosing an exit and other activities),
egress (including way®nding, movement towards an exit, crowd ¯ow and other factors), design of escape routes, exit numbers and widths, and the psychological and
physiological in¯uence of exposure to heat and smoke on escape behaviour.
Assessment of these processes for any particular ®re scenario is aimed at calculating the time required for escape. Fire safety engineering design relies upon estimation of these critical time dependent features.
1.3. Major phases of evacuation
For the estimation of time dependent features of evacuation, the behaviour of
occupants is considered in terms of two main categories of processes. In the British
and International Organisation for Standards ®re safety engineering (FSE) standards
BSI DD240 (British Standards Institution, 1997) and ISO TR13387-8 (International
Organisation for Standardisation, 1999). These are de®ned as pre-movement processes and movement (or travel) processes. These are de®ned as follows:
1.3.1. Pre-movement processes
Pre-movement processes begin at an alarm or cue and end when travel to an exit
begins. There are two components:
Recognition (this begins at an alarm or cue and ends with the ®rst response):
during this phase occupants continue with pre-alarm activities (e.g. shopping,
sitting, eating, watching football) and
Response (this begins at the ®rst response and ends when travel to an exit begins):
during this phase occupants carry out a range of activities (e.g. stopping
machinery, securing money or other risks, gathering children and other family
members, investigating the situation, way®nding, alerting others, ®ghting ®re).
1.3.2. Movement processes
Movement processes begin when travel to exits begins, and end when occupants
reach a place of safety or leave the building (where evacuation is appropriate).
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159
These de®nitions obviously represent a simpli®cation of the complex and varied
sequences of actions that individual occupants can engage in during ®res. It is
important to recognise that occupants can engage in a considerable range of activities involving movement during the ``pre-movement'' period. In this context, the
term ``movement processes'' implies deliberate movement towards exits or through
escape routes with the intention of leaving the building or reaching a place of safety.
Behaviours occurring during the pre-movement phase may involve occupants moving around for other reasons, such as shopping or seeking information. In this context, ``recognition'' indicates that by the end of this period, an occupant or a group
of occupants have recognised the need to cease normal activities and respond to the
developing emergency. ``Response'' indicates the variety and sequence of activities
engaged in to deal with (cope with) the developing emergency, but before the action
of evacuating via a chosen escape route is begun.
It is also important to recognise that these processes can be analysed both in terms
of individual occupants and populations of occupants in various locations within a
building. For each individual occupant, it is possible to measure (or de®ne in an
evacuation calculation) a pre-movement and movement time. For a group of occupants within an enclosure, pre-movement and movement times may be expressed as
average values, or in terms of time distributions (depending upon the complexity of
the analysis). Where occupants are distributed in di€erent enclosures within a
building, it is possible to determine di€erent pre-movement and movement time
distributions for di€erent enclosures.
With regard to the analysis of movement processes, it is necessary to consider the
time taken for occupants to travel to enclosure exits leading to escape routes and
the patterns of occupant ¯ow through the escape routes.
In multi-enclosure occupancies where the occupants are widely distributed (such
as hotels or apartment blocks) pre-movement time is often the major determinant of
evacuation time, especially the pre-movement times of the slowest occupants to
respond. Travel distance also becomes relatively more important. In crowded situations, such as busy shops or theatres, evacuation time depends mainly upon the premovement times of the ®rst occupants to respond and the movement times of the
whole occupant population. The ®rst occupants to respond form the fronts of
the queues at the exits and determine the time from alarm to queue formation. After
this, time to clear an occupied enclosure depends mainly upon exit route choice and
the ¯ow capacities of exit routes. In prescriptive design, it is normal to discount the
largest exit on the assumption that one exit may be blocked by ®re. The remaining
exits should then provide sucient ¯ow capacity to enable any enclosure to be
cleared within a certain period of time (for example 2.5 min in the UK), providing
the evacuating population is distributed evenly to these exits. In practice, occupants
tend to favour certain exits or escape routes over others, so that design clearance
times may not be achieved (see Section 3.3.6).
Reasonable calculation models exist for the estimation of movement time (Pauls,
1995; Nelson and MacLennan, 1995). Pre-movement times are poorly described and
quanti®ed. This is especially true when the design of warning systems and emergency
management strategies are inferior, so that occupant response on any particular
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occasion is likely to be slow and unpredictable. For evacuation calculation times to
become a viable component of ®re safety engineering, it is, therefore, vital that a
database of pre-movement times and pre-movement time distributions is obtained
for a variety of occupancy types and a variety of building design and ®re safety
management strategies.
2. Brief description of methods used for behavioural studies
Research at FRS (the Fire Research Division of BRE), includes analysis and
quanti®cation of occupant behaviour so that safety implications and escape time can
be predicted for a range of occupancies and designs. Evacuation studies have been
conducted using video and questionnaire analyses for a range of occupancy types
(Purser and Raggio, 1995; Purser and Bensilum, 1999). Fire investigations. involve
studies of occupants' experiences and responses to developing scenario (Purser, 1994;
Purser et al., 1998). The results are used for the development of calculation methods
and computer models for use in ®re safety engineering design; also in the development
of FSE standards (BSI DD240 and ISO DIS 13387-8). The following sections include
brief outlines of a number of studies illustrating the behaviours occurring during
evacuations and providing some examples of the quantitative pre-movement and
movement time data and data distributions obtained. Of particular interest was the
nature and timing of pre-movement and movement behaviour for occupants in different types of occupancies and di€erent settings, and the in¯uence of cues, warnings
and ®re safety management on evacuation behaviour and evacuation times.
3. Results of studies of occupant behaviour in ®re
Traditional FSE calculation methods for means of escape are very simplistic and
tend to assume that as soon as ignition occurs, all the occupants immediately disperse
to the nearest exits. In reality, occupant behaviour is much more complex, and heading
directly to the exits often comprises the smallest part of the time required for escape
(Proulx and Sime, 1991; Sime, 1994; Sime, 1998). These behaviours are illustrated by
reference to a few examples of occupant behaviour in both real ®re emergencies and
evacuation studies conducted by researchers of the Fire Safety Engineering Centre,
BRE in a range of building types. Occupant behaviour in evacuation studies is considered to be similar to that in real ®re emergencies in which the majority of the occupants evacuate in response to alarms without coming into direct contact with ®re and
smoke (provided they are not aware in advance that an evacuation is planned).
3.1. Real ®re incidents
3.1.1. Clothing store
Table 1 summarises the sequence of events during a ®re in a clothing store (Purser,
1998) captured by security camera recordings. The ®re occurred during the afternoon
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161
Table 1
Sequence of events in clothing store ®re. Reproduced by permission of BRE Ltd
Time from ignition (min.s)
Occupant behaviour
0.19
Fire approximately 0.5 m ¯ame height. Customer sees ®re and warns
shop assistant who investigates and goes to fetch ®re extinguisher
Assistant ®ghting ®re with extinguisher, ¯ame height approximately 1 m,
®re quite large, assistant fails to extinguish and moves away
All this time people are entering the shop, passing the ®re, shopping, and
waiting at the checkout to pay for goods.
Shop ®lling with smoke, people reluctant to leave shopping
People evacuating through thick smoke
Sta€ evacuating
A few people occasionally re-enter near doorway
Front doors shut from outside
1.19
0.19±3.30
3.30
4.00
4.15
4.00±5.00
6.00
and the video switched between four cameras, one inside the store near the ®re, one
on the opposite side of the sales ¯oor to the ®re, one showing the checkouts, and the
fourth showing the main front exit to the street. There were approximately 20±30
customers in the shop and ®ve sta€ members. Most occupants were in the front area
at the checkouts, but a number were dispersed in the sales areas, occasionally in the
vicinity of the ®re. During the period of the ®re, a number of people left or entered
the store carrying out normal shopping activities. There was no sound track on the
video so it is not possible to be certain that an alarm sounder was triggered, or when
this might have occurred. It is likely that a store such as this would have had at least
a manually triggered sounder alarm system, and that this would have been set o€ by
sta€ discovering the ®re. Even if this was not the case, it is evident from the video
that both sta€ and customers were aware of the ®re throughout most of the incident.
In this example, the occupants were very slow to respond, but all left eventually
without injury.
3.1.2. Department stores
Two ®res in department stores that resulted in fatalities were the Manchester
Woolworth's ®re (Home Oce Fire Department, 1980; Sime, 1994; Purser, 1998)
and the Chester®eld Littlewoods ®re (Derbyshire Fire and Rescue Service, 1993;
Purser, 1998; Purser, 1994; Fig. 1). The Woolworth's ®re involved mainly furniture
while the Littlewoods ®re involved mainly clothing. In both cases rapid ®re growth
occurred on an upper sales ¯oor containing restaurants and sales areas. Both resulted
in large numbers of people being trapped in toxic smoke before they could evacuate.
The smoke from the furnishings in the Woolworth's ®re was highly toxic and caused
a number of deaths. In the Littlewoods ®re, the smoke was dense but of a relatively
low toxicity so that most people escaped without serious injury, although there were
two deaths, mainly resulting from smoke inhalation and carbon monoxide poisoning.
There are a number of similarities between the behaviour of occupants in these
two incidents. Both cases involved occupants in restaurant areas adjacent to sales
areas, and in both cases, problems occurred with the evacuation of these occupants.
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Fig. 1. Chester®eld Littlewoods Department Store Ð Fire Floor. Reproduced by permission of BRE Ltd.
In the Woolworth's ®re, occupants were unaware of the ®re during the early stages.
The alarm was raised by a painter who alerted the management and shouted
to occupants of the restaurant who had not seen the ®re. It was reported that some
occupants of the restaurant were slow to react and some were reluctant to leave
quickly when the alarm was ®rst raised. The 100 or so occupants of the restaurant
e€ectively had only one exit available to them (the Oldham Street stairway), a
situation that also occurred during the Littlewoods ®re. The rapid ®re growth
resulted in rapid smoke logging and obscuration of the exits, so that some occupants
became trapped in smoke. Based upon the nature of the materials involved and the
results of full-scale tests conducted at BRE, this smoke would have been highly
toxic, resulting in rapid intoxication.
The behaviour of occupants during the Littlewood's store ®re has been investigated in some detail by the author (Purser, 1994; Purser, 1998). The store is on a
sloping site with the front at ®rst ¯oor level and the rear at street level. The main
sales area contained clothing on racks. On the morning at the time of the ®re (10:00
hours), there were around 35 sta€ in the building. On the ®re ¯oor, there were
approximately 17 sta€ and 70 customers. There was one assistant and only a few
shoppers on the sales ¯oor area, but the restaurant at the front of the building was
quite full. The diners consisted largely of retired people and young mothers with
children. A few examples of the responses of occupants illustrate some of the range
of behaviours carried out and the time needed for their execution. The ®re was
started deliberately in polyester coats on a wall rack. It was discovered almost
immediately (¯ames approximately 1 foot high) by two female shoppers who shouted
and attracted the attention of the sales assistant on the till. The women then left by
the rear doors and walked round to the front of the store, arriving just before the ®re
brigade (walking time estimated at approximately 2 min). The store was already
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
163
completely smoke-logged and people were climbing out of the front windows onto a
®rst ¯oor ledge. Inside the store, the sales assistant had gone to a manual call point,
started the alarm and instigated the emergency procedure. She then went to a set of
triple doors, the only available exit from the restaurant, and held them open to assist
people through. The ¯oor supervisor, who came out of her oce and went to
investigate, was accosted by a male customer demanding a ®re extinguisher. She
went for an extinguisher and they attempted to ®ght the ®re while the customer's
wife waited. The ®re grew very quickly along a wall of clothing on racks, and was by
now too big to extinguish. At this point, a number of sta€ members descended to
this area of the ®re ¯oor from the ¯oor above. They proceeded immediately to the
exits. The customer's wife then suggested that they should leave the building. The
male customer, his wife and the ¯oor supervisor then left the building by the rear
(street level) exits. Customers in the sales area during the period of early rapid ®re
growth remarked that diners at the restaurant were slow to move.
Meanwhile, the diners in the restaurant had heard the alarm and were responding.
An adult family group included a brother and sister and their elderly mother. The
sister heard the alarm, saying that it was probably a ®re drill, but her brother saw
the ¯ames and said they must leave. They went across to the exit doors, slowly,
because of their elderly mother. On the way they stopped to assist a woman to
remove a baby from a high chair. They reached the exit stair but became enveloped
in smoke on the stairs. Two young mothers were in the restaurant with a baby and a
toddler. One woman took her friend's toddler to the toilets, which were in a deadend situation, the other remaining with the baby in a high chair. When the ®re
started, she released the baby (with help) and started to move towards the exit
doors. As she neared the doors she saw her friend coming from the toilets with her
son. They left but were caught on the stairs by the smoke. The woman had to sit
down on the stairs holding the baby and feel her way down until she emerged into
clearer air at a lower level. A retired couple had also split up in the restaurant when
the wife went to the toilet. When the ®re started her husband went towards the toilets
with a female sta€ member. They both went into the female toilets and knocked on
the stall doors. Several women emerged, none of whom was his wife. The man
returned to the sales ¯oor only to be trapped in dense smoke at the queue that had
formed at the exit doors. A member of sta€ (who had descended from the sta€ ¯oor
above) entered the ®re ¯oor from these doors and directed people over towards the
windows. The man managed to get out of a window onto the ledge from which he was
rescued. Another elderly couple were found dead (from smoke inhalation and carbon
monoxide poisoning) after the ®re in the servery area. The wife had bad arthritis.
A particular problem with this ®re was the very rapid ®re growth and spread in
the clothing on the wall racks. The material, mainly polyester, produced large
amounts of smoke and it is estimated that the whole sales ¯oor became smokelogged within a very short time, possibly approximately 2 min after ignition. The ®re
was discovered almost at ignition and the alarm raised within approximately 1 min,
but this left little time for the restaurant occupants to respond and evacuate. The
fact that only one set of doors was e€ectively available to them had an important
impact on the evacuation time, a queue forming at these doors.
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3.1.3. Football stadium ®re
The Bradford Football stadium ®re (West Yorkshire Fire Service, 1985; Woolley,
1985; Purser, 1998) which was captured on television, provides another example of
occupant behaviour in a developing emergency. As with the clothing store ®re, the
video record shows occupants being rather slow to respond to the initial situation.
The ®re started in accumulated rubbish under the wooden stand. During the early
stages, when smoke and heat was coming up through the ¯oor, spectators cleared
the immediate area but showed little sense of urgency to evacuate the stand. A
number of ocials, including police were in the vicinity of the a€ected area, observing the smoke coming up through the ¯oor. Stand occupants remote from the seat
of the ®re were initially una€ected. The ®re then ¯ashed over in the space under the
stand, and very soon afterwards the stand itself had ¯ashed over, so that a number
of people were badly burned as they tried to escape onto the pitch.
3.2. Key aspects of occupant behaviour
These few examples illustrate some of the key features of occupant response to ®re
emergencies. People are not in buildings with ®re uppermost in their minds, but for
other purposes to which they have a considerable commitment. In order to attend to
some other demand they have to recognise its importance and cease their normal
activities. The early cues to a developing ®re emergency are often ambiguous, so that
some time may elapse before occupants become fully aware and convinced of the
need to change their behaviour. The early cues in the clothing stores may have been
ambiguous to some occupants, such as a distant commotion, or a sounder going o€
which might not have been a ®re alarm or might have been a ®re drill. At the football match the ®rst signs of smoke might not have been considered immediately
threatening, either by the occupants or the authorities. The stand occupants were
out in the open, and initially the ®re was a long way away from most of them.
The clothing store and the football match also illustrate to some extent the
``friendly ®re syndrome'' in which people may not feel threatened initially and often
misunderstand the rapid rate at which ®res, particularly ®re inside enclosures, can
grow. Occupants may wait too long before attempting to evacuate and may become
trapped. In experiments conducted for Building Research Establishment (Canter et
al., 1980), subjects who were shown a series of timed photographs of a growing
domestic ®re greatly underestimated the rate of ®re growth. The time people take to
cease their normal activities and begin to respond to the emergency therefore
depends on a range of variables. Once occupants have recognised the need to
respond to the emergency, they cease their normal activities and begin a range of
other activities. These activities often do not immediately include heading for the
nearest exit. In the examples described, a variety of activities were engaged in. In
the clothing store, in Littlewoods and probably also in the football stadium, the ®rst
activities of the people near the ®re were to warn others by attracting the attention
of sta€. In the clothing store, the response of sta€ was to ®ght the ®re. In Littlewoods, the ®rst response of sta€ was to raise the alarm and assist evacuation, while
other sta€ and a customer tried to ®ght the ®re. In the restaurant, the ®rst actions
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
165
were to seek information, and then to gather family members. Only when these
important activities were completed did occupants begin to move towards the exits.
Other activities people engage in are stopping machinery or securing money or other
risks, investigative behaviour to ®nd the source of the ®re when an alarm is triggered
and ®nding the appropriate exit route.
When these various behaviours are completed occupants may decide to evacuate
(depending upon the situation). When they decide to evacuate they ®rst make a
choice of exit route and then start to evacuate. Often occupants will try to leave
a building by the way they entered it and ignore other emergency exits or escape
routes (Sime, 1994). The evacuation process may involve further elements of way®nding and choice of routes, depending upon the complexity of the enclosure and
the developing situation (Proulx and Sime, 1991; Sime, 1998). When occupants are
all together in a single enclosure, such as a shop or theatre, then the range of times
to start an evacuation tend to be similar; when occupants are dispersed in a multienclosure building such as a hotel, then there is likely to be a wide variation in times
to start evacuating (British Standards Institution, 1997; International Organisation
for Standardization, 1999). In a building such as a hotel, when sounders are used as
alarms, it is quite common for occupants to ignore them completely, particularly
those remote from the ®re.
If the escape route is blocked by smoke or ®re, then occupants have to make further choices about whether to continue or not, and if they continue, they may be
a€ected physiologically by exposure to toxic smoke and heat (Purser, 1996).
Another aspect of ®re safety and occupant behaviour of prime importance is ®re
safety management. This includes the way in which occupants use the building and
its systems before an emergency, the provision for warnings, occupant training
and the ®re emergency plan as well as the management of an emergency when it
occurs. The clothing store incident illustrates how delays in implementing an emergency evacuation and in shutting down tills resulted in a prolonged evacuation time.
At Chester®eld, the response of sta€ and customers appears to have been appropriate, but the rapidity of development of the ®re in relation to the building features
left little time for occupants to escape in safety. At Bradford, ®re safety management
issues are evident in relation to accumulated rubbish, locked exits and delays in
evacuating occupants.
3.3. Evacuation studies
Evacuation studies have been conducted in a range of occupancy types in order to
obtain quantitative data on emergency behaviours (Purser and Raggio, 1995; Purser
and Bensilum, 1999). They also illustrate the importance of some features of occupant behaviour already described in relation to the ®re incident investigations. The
following sections show a few examples.
3.3.1. Committee room
The ®rst example illustrates a common ®nding, that pre-movement time is often the
greatest part of evacuation time. This is important because most egress calculation
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D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
methods used for building design purposes concentrate on travel time and ignore
pre-movement time, which can lead to serious underestimates of evacuation time.
BRE monitored an unannounced evacuation of a 17-storey oce building in Chiswick. Part of this involved a study in an oce meeting room using a hidden camera
(Purser and Raggio, 1995). The meeting room was on the third ¯oor of the building.
Outside the meeting room was a foyer area, with an escape stair approximately
6 m from the meeting room door. Fig. 2 shows the position of occupants in the
meeting room when the alarm sounded. The camera was in the bottom left corner of
the room pointing towards the door. The occupants, who were not regular visitors
to the building, were engaged in a committee meeting and were exposed to a recorded
voice alarm message following a sounder alert (total alarm time 17 s). They were
unaware that an evacuation was to take place. Table 2 details the recognition and
response times of the each of the occupants. The occupants responded quickly after
hearing the message, but engaged in activities such as gathering coats and belongings before leaving the room. One occupant left the room and then came back to
retrieve a jacket. These activities required 51 s on average, while the time taken
to reach the door was only 5 s. Once outside the room, approximately a further 5 s
were required to reach a protected escape route. This shows a rapid and ecient
response obtained using a voice alarm system. This compares with the slow response
in the clothing store.
3.3.2. Class room study
In further experiments subjects at Middlesex University were invited to take part
in a psychological pro®le questionnaire study, which provided a cover activity for
the true study (Raggio, 1996), which was to examine the behavioural responses to the
alarms and compare the eciency of an alarm bell and recorded messages when
motivating groups of people to evacuate. In this study, subjects signed up for one of
seven di€erent groups (group size 6±9 persons) which were examined at di€erent
times of the test day. They sat at desks in a ®rst ¯oor teaching class room covered by
Fig. 2. Positions of occupants in committee meeting room during hidden camera monitored evacuation.
Reproduced by permission of BRE Ltd.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
167
Table 2
Response times of occupant committee meeting room during hidden camera monitored evacuation.
Reproduced by permission of BRE Ltd
Person
Recognition time (s)
Reponse time (s)
Travel to exit time (s)
Total time (s)
1
2
3
4
5
6
7
8
9
10
11
12
16
15
17
20
16
18
?
16
?
?
?
?
40
17
20
30
30
39
?
30
?
?
?
?
5
5
2
3
6
5
3
13
?
?
2
4
61
37
39
53
52
62
67
59a
55
65
71
51
Average
17
29
5
56
a
Re-enters to collect jacket. Leaves again at 00:01:24.
hidden video cameras and were asked to ®ll in a questionnaire. As each group settled
to their task an alarm consisting of either a sounder, short voice alarm message or a
longer voice alarm message was presented. Each alarm was tested on two groups
(with a spare group in case a test failed). The behaviour and response times were
recorded. The results (summarised in Table 3) con®rmed those from earlier studies
(Bellamy and Geter, 1991; Proulx and Sime, 1991), which were that a voice alarm
was more e€ective and produced a quicker response than a sounder. In these
experiments the short message produced the quickest response. However, in these
group situations it was found that the behaviour, and in particular response time,
was very dependent upon a few key group members, who either facilitated or
inhibited the evacuation in di€erent tests.
3.3.3. Shopping centre study including a restaurant
Another evacuation study in a di€erent setting (Purser and Raggio, 1995; Purser
and Bensilum, 1999) also shows the importance of pre-movement time and the e€ect
of a voice alarm system. This was a study of an unannounced evacuation of Harlow
shopping centre at around 10:00 hours. Included in the study was a restaurant
Table 3
Pre-movement times for alarm sounder and voice message experiments. Reproduced by permission of
BRE Ltd
Condition
n
Mean (s)
Standard deviation
Minimum (s)
Maximum (s)
Sounder
Long message
Short message
17
15
16
35.4
22.9
12.9
15.8
4.0
7.3
16
17
5
63
31
26
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D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
Fig. 3. Evacuation times for each customer leaving a restaurant. Reproduced by permission of BRE
Ltd.
within the shopping centre. Approximately 16 people were present including the
sta€. Some customers were seated while others were at the counter. Fig. 3 shows
the recognition, response and movement times of 11 customers. From Fig. 3 it can
be seen that the evacuation was rapid, clearance being achieved within approximately 1 min. By far the majority of the evacuation time consists of pre-movement,
i.e. recognition and response times. The voice message announcement ended after
45 s, so that the movement phase either anticipated the end of the message or started
within 15 s of the completion of the message. There was no obvious instruction or
guidance from the sta€ at this stage. One occupant was a wheelchair user, whose
helper reacted quickly (total pre-movement time 50 s). An elderly man near the side
of the restaurant was being directed by sta€ 86 s after the alarm. Several plates of
un®nished food were left. Once occupants have left the restaurant they still have to
leave the shopping centre, although the large open mall area outside the restaurant
would constitute a place of relative safety.
These results illustrate that it is possible to achieve rapid clearance of a restaurant
in a well managed situation. Following the Woolworths ®re it was suggested that
occupants were slow (or refused) to leave food that they had paid for and that
this was a factor in their being trapped by the ®re (Home Oce Fire Department, 1980; Sime, 1994). There were also suggestions that people in the restaurant
were slow to move in the Littlewoods ®re (which had a sounder rather than a voice
alarm; Derbyshire Fire and Rescue, 1993; Purser, 1998). However, in the Littlewoods ®re the ®re growth was very rapid and it is estimated that the restaurant
occupants must have moved within a minute of the alarm sounding, so that the premovement times must actually have been relatively short. This may have been
because they could see the ®re. At Woolworths the occupants in the restaurant could
not see the ®re during its early stages of slow growth, which may have delayed their
initial responses.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
169
3.3.4. Supermarkets and foodhalls in retail stores
Monitored evacuations from two supermarkets (one attached to the Harlow
shopping centre) and two foodhalls in retail stores have been studied as part of this
work (Purser and Raggio, 1995, Purser and Bensilum, 1999). The two supermarkets
had voice alarms systems and the foodhalls sounders. An important consideration
with many shopping and assembly buildings is that two stage alarms systems are
often used. The initial alarm alerts security or management, who are then able to
investigate the incident before deciding whether or not to trigger the general alarm.
This prevents evacuations from occurring for trivial reasons but does add a certain
amount to the escape time from ignition. During real ®re incidents there are therefore two pre-movement times to consider, the pre-movement associated with the
pre-alarm and the pre-movement time associated with the general alarm. The
monitored unannounced evacuations for the two supermarkets started with a general alarm so the pre-alarm times were not studied, and an estimate of these times
would need to be added to provide an estimate of the total evacuation time from
detection of a ®re. In general the pre-movement and travel times for the supermarkets were short due to a rapid response by customers aided by sta€ actions. The
maximum pre-movement times and times to ®nal exit are shown in a summary
table, Table 4.
Also summarized in Table 4 are the maximum pre-movement times and times to
®nal exit for a basement food hall in a retail store containing a food hall and a
clothing section. This work was carried out in conjunction with University of Ulster
and is described in more detail with their analysis of the data elsewhere (Shields et
al., 1997, 2000; Ashe and Shields, 2000). The foodhall with clothing section was a
single storey building with 10 exits available around the building periphery. Fig. 4
shows the results of data analysed at BRE for the distribution of pre-movement
times for customers in the store. This shows a considerable variation from the ®rst
people to respond (within 4 s) to the last after 1 min 50 s. The mode response time
was approximately 20 s. The means of alerting the occupants was via a sounder.
The video recording shows that the sta€ reacted within seconds to the alarm,
shutting down tills and directing customers to exits (especially when a supervisor
was present), except in the customer services area, where customers were served for
40 s after the alarm. In contrast, the shoppers took very little notice of the alarm
sounder, the majority continuing to shop, pushing their trolleys around and taking
items from the shelves. The sta€ responded quickly and ushered the shoppers to the
exits. This emphasises the ine€ectiveness of sounders in buildings where the occupants are not trained to respond, and the e€ectiveness of a well-trained sta€ with
an ecient emergency response plan. In general supermarkets empty quickly
because a large number of sta€ are usually available to put into practice an emergency plan consisting of a sweep of the sales ¯oor. Fig. 5 shows the distribution of
times for the total evacuation of the store (pre-movement plus movement time).
This also shows a distribution of times, the ®rst person leaving immediately, the last
after 2 min 45 s and a mode time of approximately 1 min. Notice that most of these
distributions are skewed and the time the last person will leave (usually sta€) is
dicult to predict.
170
Table 4
Maximum times (decimal minutes) for phases of evacuations from experiments in di€erent building types. Reproduced by permission of BRE Ltd
Alarm type
Recognition Response Total
Travel to
Total to
Total to
pre-movement protected route protected route ®nal exit
University teaching lab
Sounder
Voice (long)
Voice (short)
1.05
0.52
0.43
0.40
0.18
0.17
1.23
0.60
0.55
Recorded voice
0.33
0.20
0.03
0.67
0.40
0.13
1.00
0.60
0.17
0.9
0.43
0.2
0.13
±
±
±
16 storey oce
Room 311, visitors
Room 312, sta€
Snack bar
Room 208
Floor 15, sta€a
Floor 16, sta€a
Floor 17 sta€a
Main stair A
Main stair B
Main stair D
Oce building: Equinox
test, visitors
BRE oces/labs
Building 4
Building 18
Building 19
Council oces, Amber Valley
10-storey oce, City of London
Bell
Voice
Sounder
Sounder
Sounder
Sounder
Sounder
0.35
0.40
0.68
0.28
0.32
0.32
0.32
1.23
0.80
0.75
1.18
3.43
2.80
3.13
1.73
1.30
0.92
1.45
7.23
6.73
7.20
8.73
8.97
1.33
11.0
0.50
1.8 approx.
1.5 approx.
1.5 approx.
2.0 approx.
<2 approx.
2.25
1.92
1.92
2.70
6.50
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
Building
Voice/announcement
(End of show)
(End of pres.)
3.92
2.0 approx.
1.0 approx.
6.40
4.67
1.48
Foodhall, basement
Foodhall, ground ¯oor
Supermarket, Herts
Supermarket, Shopping centre
Clothing store, Scotland
Sounder
Sounder
Sounder?
Voice
?
1.58
0.92
1.5 approx.
2.5 approx.
4.0 approx.
4.30
2.75
1.92
3.00
4.80
Hospital outpatients
Waiting room 1
Eye clinic waiting room
Voice
0.48
0.48
1.48 approx.
1.48 approx.
Leisure centre
Sounder?
Library
Sounder
Underground station, Tyne and Wear Bell
Voice
2.67
1.8 approx.
9.00
1.15
Restaurant, shopping centre
1.43
Voice
4.20
2.21
>15
5.45
4.62
a
Indicates phased evacuation : pre-movement components are from ``evacuate message'', times to protected route and ®nal exit are from start of alarm.
Negative pre-movement time indicates movement after ``. . .wait for further instructions. . .'' message but before ``. . .evacuate now. . .'' message.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
Arts theatre
Manchester theatre
BRE lecture theatre
171
172
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
Fig. 4. Frequency distribution of pre-movement times Ð retail store with foodhall. Reproduced by
permission of BRE Ltd.
Fig. 5. Frequency distribution of people leaving from all exits Ð retail store with foodhall. Reproduced
by permission of BRE Ltd.
3.3.5. Theatre evacuation
An example of a monitored evacuation dominated by travel time was carried out
in a theatre (Purser and Raggio, 1995; Purser and Bensilum, 1999). Fig. 6 shows a
plan of the ground ¯oor of a theatre including the stalls. There was also a ®rst ¯oor
circle. An unannounced evacuation was carried out towards the end of an evening
performance. There were approximately 160 people in the stalls and 140 in the circle,
plus approximately 10 sta€. This represented 46% of the full seating capacity. One
exit from the stalls and the circle were considered blocked by the ``®re''. A ``double
knock'' (i.e. two stage) alarm system was used and 56 s elapsed before the theatre
manager came onto the stage, interrupted the performance and instructed the audience to leave, stating that the front door left and circle left exits were unavailable.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
173
Fig. 6. Theatre evacuation: ground ¯oor plan showing stalls, escape routes and exits. Reproduced by
permission of BRE Ltd.
Fig. 7. Theatre evacuation Ð pre-movement times in circle and stalls. Reproduced by permission of BRE
Ltd.
174
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
Fig. 7 shows the pre-movement times for the majority of people in the circle and
stalls in camera view, timed from the beginning of the manager's announcement.
The ®rst members of the audience reacted to the announcement when the manager
had almost ®nished the instructions, especially in the circle.
In the stalls, some people remained seated when they saw the queues formed at the
exits. Although this somewhat increased the pre-movement times it had no e€ect on
the total time required to evacuate the stalls.
Fig. 8 shows the ¯ow rates at di€erent doors during the evacuation time from the
activation of the alarm panel. The ®rst of 300 occupants began to move after a premovement time of 12 s after the start of the manager's emergency evacuation
announcement, which is 1 min 6 s after the pre-alarm was triggered. The ®rst occupants of the stall and circle emerged from the auditorium exits 30 s later, or 42 s
after the beginning of the emergency announcement from the stage. There was one
exit available from the circle onto two alternative stairs and three exits available from the stalls, all into the ground ¯oor foyer. In practice only one stair was
used from the circle and almost all stalls occupants were encouraged to use door B.
Occupants were also encouraged by sta€ to leave the theatre via emergency exit
door C. This led to considerable congestion in the foyer and a slow total evacuation
time of almost 7 min, despite the fact that the theatre was only around half full.
4. Discussion
4.1. Distributions of pre-movement and travel times
A general problem with representing the data from evacuation studies is that each
individual occupant has a pre-movement and travel time. When dealing with a
population it is possible to consider the distributions of pre-movement times and
Fig. 8. Theatre evacuation: occupant ¯ows from exits and stairs indicated in Fig. 6. Reproduced by
permission of BRE Ltd.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
175
travel times, and how these interact to produce total evacuation times. When evacuation times are modelled for ®re safety engineering purposes di€erent methods can
be used depending upon the sophistication of the analysis modelling method. For
computer evacuation simulation methods in which each occupant is modelled as an
individual, it is possible to impose a pre-movement time distribution similar to those
obtained in evacuation studies. For simpler evacuation calculation methods a single
®gure may be used to represent the pre-movement time of a population. Although
this may be acceptable, provided the ®gure used is suciently conservative, it is not
obvious which ®gure should be used. For example, it is possible to choose shortest,
mean (or median) and longest times, and to defend di€erent choices depending upon
the situation under consideration.
It may be possible to describe an evacuation quantitatively in terms of a mean and
standard distribution, except that most distributions are skewed, so that some
transform may be needed. Pre-movement and evacuation time distributions tend to
be skewed such that some individuals take much longer to move or evacuate than
the majority. Fig. 9 shows the distribution of pre-movement times for the retail store
with food hall compared to a theoretical log normal distribution of times based
upon the mean and standard deviation of a log transform of the data. The ®gure
shows a good ®t between the observed and theoretical distributions. Several other
data sets have been examined which also appear to show a log normal distribution,
although this may not always be the case. In the theatre example the pre-movement
times were in¯uenced by occupants observing the queues at the exits, and moving
only when the queue was reduced. This resulted in a more varied distribution pattern of pre-movement times. In general it is considered that a skewed distribution
such as a log normal distribution is likely to occur. It is dicult to predict when the
Fig. 9. Distribution of pre-movement times in retail store with food hall compared with a log normal
distribution. Reproduced by permission of BRE Ltd.
176
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
last individual will move or evacuate, since this is dependent on the behaviour of
that particular individual. It may be quite possible for the vast majority of occupants to evacuate within a few minutes, but for the last occupant to emerge 20 min
later. The time when the last occupant evacuates may also be an unrealistic parameter because it may vary according to the situation. In an evacuation drill for
example, the last occupant to leave is likely to be a safety ocer. Since this individual would know that there was no ®re there may be no particular urgency to leave.
On the other hand it is arguable that pre-movement times may be shorter in real
®re emergencies if the occupants can see the ®re. For any frequency distribution
the times tend to in®nity as the frequency tends to zero, so that the time when the
last individual evacuates is inherently unpredictable. It may therefore be more
appropriate to describe the evacuation time for an enclosure or building in terms of
a certain percentile or occupants evacuated. For example, the time to 95% premovement or clearance is reasonably amenable to calculation predictions. For most
evacuation drills the time logged is the time for the last occupant to leave. Reporting
the pre-movement and evacuation times of the last occupant provides a conservative
and therefore ``safer'' estimate of evacuation times for engineering design purposes.
Another parameter to be considered is the distribution of pre-movement and
evacuation times between di€erent evacuations. One consideration is the distribution of times likely to occur for di€erent evacuations in the same building and how
predictive a single evacuation drill is likely to be of the evacuation times for the
building. Obviously evacuation times may vary according to the scenario in a real
®re incident and this is dicult to measure experimentally, although it may be
amenable to modelling. It is possible to determine the variation between di€erent
test evacuations. It has been found that the ®re safety management plan and its
implementation on any particular occasion can have a considerable e€ect on evacuation times. If unannounced evacuations are carried out on a number of occasions
Fig. 10. Distribution of total evacuation times Ð BRE buildings. Reproduced by permission of BRE Ltd.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
177
for the same building it is possible that considerable variations might occur
depending upon which sta€ were present on any particular occasion and their attitudes and training. Fig. 10 shows total evacuation times for 59 evacuations carried
out by safety ocers of the various oce, library and laboratory buildings on the
BRE site over 5 years (Purser and Bensilum, 1999). Although this set involves a
number of buildings it does provide a large number of repeated evacuations in the
same set of buildings under the same generic management with similar occupant
populations. Apart from the common management and training situation there are
a number of other similarities between the conditions for the di€erent evacuations in
that the occupants are similar and familiar with the buildings, the population densities are small so that queuing at exits is unlikely and the buildings are low rise
(maximum four storeys) and of generally similar size. On this basis it is possible to
regard conditions of the evacuation as generally similar and compare them as a
single data set. On the whole the evacuations were very ecient with a narrow distribution of times. Based on an average travel time of around 0.5 min, this gives an
average maximum pre-movement time of around 1 min. Fig. 10 shows the frequency
distribution of times, compared with theoretical normal and log normal curves
based upon the same means and standard deviations as the real data. For this set the
data appear to be more or less normally distributed, as might be expected, with a
mean of 1.51 min and a standard deviation of 0.55 min.
4.2. Pre-movement and travel times for a variety of buildings
The examples presented in this paper have illustrated the important determinants
of pre-movement time and its relationship to travel and evacuation time for a number of di€erent building types with di€erent management and systems. The previous
section has also illustrated the variations occurring within one building set on different occasions. The work carried out by BRE has involved a wide variety of
building types with a wide range of systems under a variety of managements. Some
of these have been investigated in considerable detail while for others the data are
only partial. However, from this data set is possible to obtain an initial set of generic
data on the similarities and di€erences occurring over a range of cases.
The results for the set of evacuations studied are summarized in Table 4, which
includes data from the examples already discussed, other examples from the BRE
data set and data from the Tyne and Wear underground study (Proulx and Sime,
1991) and the Bellamy and Geter (1991) study. This gives an indication of a range of
pre-movement and evacuation times occurring in a variety of buildings. One aspect
all these buildings have in common is that none of them involve sleeping accommodation. They are all work places or public buildings in which the occupants
would be expected to be alert. Some cases involve occupants distributed in small
numbers in several enclosures (as in oce buildings), others involve occupants distributed within a single enclosure (as in shops or supermarkets) and others involve
assembly spaces (such as theatres or class rooms). For some examples occupants
would be expected to be familiar with the building, but less so for others, and a
variety of di€erent alarm systems and management are involved.
178
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
The main aspects that need to be considered are the pre-movement times and the
times to evacuate into a protected escape route. In most of the cases summarized in
Table 4 the total evacuation times to a ®nal exit involved exits opening directly from
the occupied spaces under investigation, or the buildings were relatively small, so
that time required to traverse protected escape routes was small. Exceptions were
one example involving a 16 storey oce building and another a 10 storey oce
building. For these cases time to ®nal exit is considerably in¯uenced by the travel
times in protected stairs. However, for the 16 storey building evacuation times for
occupants to enter protected escape routes were also measured. The times shown in
the table are maximum times, which tend to represent the slowest responders, for
both pre-movement and total evacuation times for the evacuation studies described
in this report and the other published data.
The data in Table 4 represent maximum pre-movement and evacuation times for
a range of di€erent building types, with a range of systems under a variety of
managements. The results show a variety of pre-movement and evacuation times.
Some times are short and similar to the BRE data (Purser and Bensilum, 1999),
others show considerably longer times, particularly in situations were warning
systems and ®re safety management implementation were poor. The data are
plotted in Fig. 11. Unlike the BRE data, these show a better ®t with a log normal
distribution. For the ®t shown, two outliers with times of 9 and 11 min were not
included in the data used for the theoretical plots.
These results illustrate that when systems and management are of a high standard,
short pre-movement and evacuation times can be achieved fairly reliably, with
similar times, in a variety of occupancy and building types. When systems and
management are poor, much longer and less predictable times are obtained. It is
possible that these data could be used to produce de®ned pre-movement and evacuation times for di€erent de®ned levels of building system and ®re safety management. In the mixed data set the mean pre-movement time was 0.89 min and the 95
Fig. 11. Mixed occupancies Ð distribution of pre-movement times. Reproduced by permission of BRE
Ltd.
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
179
percentile was 4.28 min. When this is broken down into systems using voice alarms
and systems using sounders, the ®gures for voice alarm systems: mean 0.51 min, 95
percentile 2.43 min, and for sounder systems: mean 1.63 min, 95 percentile 2.57 min.
The pre-movement times for evacuations in buildings using voice alarm systems
were therefore generally shorter than those in buildings using sounders. To some
extent this also tended to re¯ect buildings with good and less good ®re safety management. For the buildings with sounders, the di€erences are even greater when the
two very long pre-movement times from Table 4 (of 9 and 11 min) are included, with
a mean of 2.15 min, and a 95 percentile of 7.11 min. These ®ndings support the
concept that for well designed safety systems with good ®re safety management premovement times are short and predictable, while for less sophisticated and less well
managed systems, pre-movement times are longer and less predictable. For the BRE
data set, although the systems in most buildings are simple sounders, the presence of
trained sta€ and a good ®re safety management environment resulted in a mean
evacuation time of 1.51 min (pre-movement time <1 min) with the 95 percentile
over 59 evacuations of 2.41 min.
4.3. Design considerations for pre-movement times
These results indicate that for well managed oce, shops, waiting rooms and
assembly spaces short pre-movement times from a general alarm can be obtained for
groups of occupants. In most cases these are less than 2 min, but are subject to some
variation when repeated on di€erent occasions, extending up to around 4 min. One
important consideration is that the majority of these data are from unannounced
evacuation studies. This means that the majority of occupants, including the sta€
were unaware that an evacuation was about to take place. However, with any such
study it is necessary to obtain the co-operation of building management at some
level, and based upon our ®ndings we would suggest that, since evacuation management is so crucial in obtaining a rapid response, any knowledge of the situation
by management may have some in¯uence on the outcome. Also, in general,
the buildings studied tended to be well managed and the sta€ well trained, since such
buildings and management are more likely to agree to participate in research. The
long pre-movement time in the clothing store illustrates the poor performance that
can occur when sta€ fail to conduct a proper evacuation, and we have anecdotal
evidence for at least two occasions when inecient unplanned evacuations occurred
(in a supermarket and a store) under the same management as those performing well
in our study.
Another important caveat is that none of the buildings studied involved sleeping
accommodation. Based upon investigations of ®re incidents and logistical considerations it is suggested that very much longer pre-movement times would be
expected in accommodation such as hotels, hostels or domestic dwellings.
There is a considerable need to extend these studies so that an extensive database
of pre-movement times, travel times and total evacuation times can be built up for
the entire range of building and occupancy types. The best way to achieve this
and obtain the most relevant data is by means of security video placed at strategic
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D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
locations in a large number of buildings, and to encourage building managers to
release video records of real incidents as they occur (including both false alarms and
actual ®res) for research. This could then be used to build up an anonymous database of evacuation times which could be used for design and regulation purposes.
4.4. Relationship between pre-movement time, travel time and evacuation times
Another consideration when using a single number to represent pre-movement
time in engineering calculations is the interaction between pre-movement time, travel time and total evacuation time (or total time to enter protected escape routes).
For sparsely occupied spaces, particularly in multi-enclosure occupancies where the
occupants are widely distributed (such as hotels or apartment blocks) pre-movement
time is the major determinant of evacuation time, especially the pre-movement times
of the slowest occupants to respond. Travel distance also becomes relatively more
important. In crowded situations, such as busy shops or theatres, evacuation time
depends mainly upon the pre-movement times of the ®rst occupants to react and the
travel times of the whole occupant population. The ®rst occupants to begin
the movement phase form the fronts of the queues at the exits and determine the
time from alarm to queue formation. After this, time to clear an occupied enclosure
depends mainly upon the exit choice behaviour and the exit route ¯ow capacities. A
good example of this phenomenon is the theatre evacuation. In this case many
occupants remained seated until they could see the queues at the exits shorten (the
sort of behaviour common in airport lounges after a ¯ight is called). In such a case,
simply adding the maximum pre-movement time to the total travel time for the
occupant population would give an unrealistically long estimate of total evacuation
time. In other examples illustrated, such as the restaurant evacuation, the occupant
capacity was insucient to result in queuing at the exits, so that the pre-movement
time of the slowest responders and their travel times can be summed to provide a
reasonable estimate of total evacuation time. For the retail store with food hall an
intermediate situation occurred, but since the exits never reached their maximum
¯ow capacity there was little evidence of queuing and both pre-movement and travel
times were important in terms of total evacuation time.
5. Conclusions
1. Although the detailed behaviour and emergency evacuation times of individual
building occupants may be somewhat unpredictable, the behaviour and evacuation times of occupant groups and building populations are amenable to
prediction and quantitative description suitable for engineering design purposes.
2. Evacuation behaviours and times can be described in terms of a limited set
of design behavioural scenarios (related principally to the standard of ®re
safety management and warnings provision, the size of the occupant population
within enclosures in relation to exit capacity, the distribution of occupants within
and among building enclosures and whether occupants are alert of sleeping).
D.A. Purser, M. Bensilum / Safety Science 38 (2001) 157±182
181
3. In buildings with a good standard of ®re safety management and ®re safety
systems, evacuation times are short and predictable within narrow limits.
When standards of ®re safety management and systems are poor, evacuation
times become much more variable.
4. Evacuation times depend upon two major elements, pre-movement times and
movement (or travel) times.
5. Movement times are reasonably predictable according to simple established
¯ow calculation methods, providing exit choice is correctly predicted. Movement times can be considerably lengthened (particularly in assembly enclosures) when occupants favour some available exits over others.
6. Pre-movement times are subject to a wide range of in¯uences but tend to be
short and predictable in well managed buildings with good ®re safety systems
(with the principal exception of multi-enclosure sleeping accommodation).
7. For buildings involving a small range of evacuation classes in terms of di€erent
occupancy types and design behavioural scenarios, it should be possible to
de®ne default pre-movement times or time distributions which could be used
with simple egress calculation methods to calculate design evacuation times for
®re safety engineering. For larger and more complex buildings involving more
varied occupancies then more sophisticated computer evacuation models may
be required.
8. An extensive database of pre-movement times, travel times and total evacuation times should be built up for the entire range of building and occupancy
types by encouraging building managers to release video records of real incidents as they occur (including both false alarms and actual ®res) for research.
This could then be used to build up an anonymous database of evacuation
times which could be used for design and regulation purposes.
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