Filip Silov Dissertation

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An investigation into the impact of obstacles during
evacuation of shopping centre in case of fire using
Pathfinder.
A dissertation submitted to the
University of Central Lancashire
In partial fulfilment of the requirements for the degree of
Bachelor of Science with Honours
In
Fire Safety Engineering
By
Filip Silov (G20596595)
School of Forensic and Investigative Science
Supervised by
Dr. Paul Caurrie
August, 2016

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Table of Contents
Abstract.................................................................................................................................. 3
Chapter 1: General introduction ............................................................................................ 5
1.1 Introduction ..................................................................................................................5
1.2 Aim ...............................................................................................................................5
1.3 Objectives ....................................................................................................................5
1.4 Research methodology................................................................................................6
1.5 Summary of dissertation..............................................................................................6
1.6 Main Achievements .....................................................................................................6
Chapter 2: Literature review .................................................................................................. 7
2.1 Introduction ..................................................................................................................7
2.2 Standards and Regulations .........................................................................................7
2.3 Simulation Program Basics (Pathfinder) .....................................................................9
2.4 Performance Based Design (Behaviours of occupants)...........................................10
2.5 Summary....................................................................................................................13
Chapter 3: Research.............................................................................................................14
3.1 Introduction ................................................................................................................14
3.2 Methodology...............................................................................................................15
3.3 Data............................................................................................................................16
3.4 Analysis and Discussion............................................................................................20
3.5 Summary....................................................................................................................22
Chapter 4: Conclusion and Recommendation.....................................................................23
4.1 Introduction ................................................................................................................23
4.2 Conclusion .................................................................................................................24
4.3 Recommendations for Further Research..................................................................25
Annex A............................................................................................................................26
References:...........................................................................................................................28

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Abstract
Abstract of a dissertation entitled an investigation into the obstacles during evacuation of shopping
centres in case of fire using Pathfinder submitted by Filip Silov for BSc (Hons) in Fire Safety
Engineering at University of Central Lancashire in April, 2016.
For the purpose of this research, the basic industry standard BS9999:2008 “Code of practice for
fire safety in the design, management and use of buildings” is analysed.
Specific related subjects are treated in normative annexes:
- Annex E (normative) Recommendations for shopping complexes;
- Annex B (normative) Recommendations for atria.
While the Atria definition more closely describes modern shopping centre design trends, it excludes
Shopping complexes. Annex E, on the other hand, determines basic recommendations for widths
of corridors only (no open space considerations), where dimensions should be increased according
to the size of obstructions. The whole subject obviously requires improvement in the regulatory
part. The aim of this paper is to conduct series of experiments, where influence of obstacles will be
researched and analysed. For the purpose of proper modelling, and focusing on the impact of
obstructions, a section of a typical shopping mall corridor was designed. The initial dimensions
comply with BS9999 recommendations. Different scenarios were created by changing of the
following variables: number, position and size of obstacles. Position means preserving of the
obstructions along the corridor centre line, but placing them away are adjacent to shop exit doors.
In addition, the software allows application of two occupant behaviour modes: Steering and SFPE.
Both were tested in order to understand the aspects of crowd evacuation theories in the designed
conditions.

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The outcome of the work has clearly shown that neither the number of obstacles in a same row nor
their position have any influence on the egress time, for any of the tested obstacle sizes.
It was expected, that decrease of escape route widths shall increase the evacuation time. The
previous expectation was confirmed for Steering mode, where paths are determined by current and
next point in the grid. The path determines the escape route, allowing occupants to make new
decision whenever they reach the next point. In SFPE calculation, which is described as flow
model, where walking speeds and flow rates through doors and corridors are the only limitations,
there was no increase of RSET regardless even for extreme obstacle sizes. Therefore, it is
concluded that prior to any simulation, the available evacuation models need to be carefully
considered and the right one applied for specific purpose. In addition, application of specific design
solutions in regards of evacuation management (positions of emergency signs, shifting of exit
doors from corridor centre lines, etc.) could encourage occupants to escape in a manner which is
defined as the SFPE mode. This of course only after further studies which need to be conducted.
Acknowledgments
First of all I would like to thank my family for their support during my work on this dissertation
because without them and away from them I was able to complete all points asked in dissertation
brief. However main part in completing this dissertation is of course my supervisor Dr. Paul Currie
who gave me a clear vision of what is fire safety engineering, and last but not least my housemates
who always supported me to study hard and become a Fire Safety Engineers.

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Chapter 1: General introduction
1.1 Introduction
Nowadays, evacuation problem is critical since it is used in many applications. These applications
include sites where masses of people gather such as commercial shopping centres, sporting
events, transportation centres, and concerts. A relevant objective is how to consider the mobility of
pedestrians in an area in order to improve evacuation times. Focus of this research will be the
simulation analysis of evacuation of a large commercial shopping district, where particular attention
will be on impact of obstacles during evacuation. The aim of this paper is to consider the effects of
the obstacles and crowd distribution in evacuation process, to provide the occupants safety in
enclosed environments, avoiding and reducing the number of fatalities. Also, research objectives
will be to identify information that might be useful in building designing in regards of the existing
construction and safety regulations.
1.2 Aim
The aim of this project is to investigate impact of obstacles during evacuation of shopping centres
in case of fire. Egress simulation will be conducted in the agent based evacuation simulation
program in order to improve evacuation standards in shopping mall.
1.3 Objectives
 To analyse are current standards and regulations in accordance of new tendencies of
shopping mall designs, particularly various types of obstacles being installed
 To determine impact of size and location of obstacles on egress time, using Pathfinder
modelling software.
 To investigate the impact of different models of human behaviour based on simulation
experiment results.

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1.4 Research methodology
The methodology of this project relies on simulation program (Pathfinder) which can help in
answering the aim and objectives together with literature review that can contribute in building up
fire and safety standards and evacuation procedures with efficient results on evacuation in
shopping centres with obstacles available. A simulation of evacuation was chosen as a
methodology based on interest and deep understanding how obstacles can impact evacuation in
shopping centres.
1.5 Summary of dissertation
This dissertation which is divided in four chapters is consisted of multiple investigations of how size
and location of obstacles are having impact during the evacuation. In first chapter general
information are written to explain to reader what is the main aim and objectives in order to achieve
results for this topic. Beside aim and objectives, research methodology and main achievements are
collected to answer all the important questions regarding the topic. Second chapter is consisted of
literature review from the British Standards to have knowledge about designing and modelling of
shopping centres which this topic is about. To achieve real designs and models of shopping
centres and to have as close as possible results, simulation of evacuation of occupants has been
conducted in program Pathfinder. All data together with results and explanation of each simulation
can be found in chapter three. Last chapter of this dissertation is about the conclusion and
recommendations for the future work where data from the previous chapter is collected to suggest
points that are important for the researchers who will have research on the similar topic. At last
annex can be found to show basic layouts of the shopping centre simulation which is conducted in
program for simulation of evacuation of occupants.
1.6 Main Achievements
Series of simulations on how size and location of obstacles have an impact on time for evacuation
has been conducted in this research order to investigate the topic of this dissertation. Simulations
have clearly shown that number and location of obstacles didn`t result with significant delay in
evacuation. Indeed the most important factor in evacuation of occupants from the shopping centre
is their own behaviour in the set and circumstances. In conclusion investigation on influence of
obstacles should be further investigated, particular for shopping centre design as per modern
trends. Ultimately, this could be finalized with improvements in standards and design
recommendation.

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Chapter 2: Literature review
2.1 Introduction
In shopping centres, any emergency situations may involve even thousands of persons. Design of
buildings, escape routes, emergency signs and location of exits are amongst main factors which
have effect on evacuation progress. In stressed behaviours while occupants are pushing each
other to get out of rooms in compartments, location of obstacles may affect time required for
occupant’s safe rescue. On the other side it is obvious that any obstacle or barrier placed on the
escape route of the occupants will reduce the time of traveling due to reducing occupant density
which gives increasing rate of flow (Parisi, D and G. Dorso, C. 2011). Dozens of papers argued that
obstacles may be a reason of reducing the time of evacuation and having a stable flow (Helbing, D
et al 2005), (Krichner, A et al 2003).
2.2 Standards and Regulations
The most important thing during emergency situations in shopping centres is motivation to escape.
In researches of many fatal fires and evacuations, it was observed that occupants are likely to
underestimate how fire can quickly spread, and in combination with other factors such as usual late
warnings, the evacuation starts with delay. Instead of single level shops, multilevel covered
shopping centres came into use, with much different varieties of sizes of units, and more free
space between shoppers and barriers, which are not created for occupants. Old shopping centres
were likely planned to be designed in straight axial lines, where todays shopping centres are
designed with more complex circulation patterns, to have better and bigger pedestrian flow.
Structure material choice has become important factor in designing. Lightness in structure became
main aim in order to have a good design of shopping centre. Places where people gather such as
large open spaces or atria are more common. Accent on lifts and escalators are pointed in
shopping centres in order to make easy and fast circulation. As per entertainment part, fountains
and large displays are set in order to increase occupant shopping time together with facilities for
children and other uses that can be interesting to add in order to develop and improve existing
shopping centres (BS9999, paragraph E.1.1, page 332, 2008).

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The source of upper descriptions is found in BS9999:2008, Annex E (normative):
“Recommendations for shopping complexes”. Although this Annex is giving particular
recommendations for shopping centres, in section E.3. “Planning of escape”, only corridor type
areas are analysed. When obstacles are planned along the evacuation routes, it is recommended
to calculate the required width and substantiate the corridor width (BS999:2008, clause E.3.1.3.,
p.339-340 and figure E.5., p.341).
For atrium type of areas (cause E.1.4, p.333), reference is made to Annex B (normative)”:
Recommendations for atria”. In Section B “General” of this Annex, it is clearly stated that “The
principles presented in this annex are applicable to all building types containing atria other than:
1)…3) malls in shopping complexes” (p. 262). Clause (B.4.2. “Escape routes” p.265) emphasizes
the specifics and difficulties of designing such areas, without any reference to obstructions in Atria
spaces.
In lack of specific recommendations, it is obvious that for the purpose of safety planning, one
should conduct evacuation simulations for areas designed with obstacles.
In order to get better understanding of the subject, the author searched for similar researches.
Several published papers of similar nature are found, such as: Public Evacuation Process
Modelling and Simulation Based on Cellular Automata (Zhikun Wang, 2013). Simulation of
Optimized Evacuation Processes in Complex Buildings Using Cellular Automata Model (Rong Xie,
2014). Simulation of Optimized Evacuation Processes in Complex Buildings Using Cellular
Automata Model (Rong Xie, 2011) etc. By rule, publications are focused on evacuation theories,
evacuation modelling and testing of specific software. Impact of obstacles is not analysed in
details, instead one can find standard statements that obstructions surely reduce egress time and /
or should be excluded from evacuation routes.

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2.3 Simulation Program Basics (Pathfinder)
Pathfinder uses a 3D geometry model. Within this geometric model is a navigation mesh defined as
a continuous 2D triangulated surface referred to as a "navigation mesh." Occupant motion takes
place on this navigation mesh. The navigation mesh is an irregular one‐sided surface represented
by adjacent triangles. Pathfinder supports drawing or automatic generation of a navigation mesh
from imported geometry – including Fire Dynamics Simulator files [McGrattan et al., 2007],
PyroSim files, and Autodesk’s Drawing Exchange Format (DXF) files. Since occupants can only
travel on the navigation mesh, this technique prevents the overhead of any solid object
representation from affecting the simulator. When the navigation mesh is generated by importing
geometry, any region of the mesh blocked by a solid object is automatically removed. For overhead
obstructions, the mesh generator considers any obstruction within 1.8 meters (6 feet) of the floor to
be an obstacle. The navigation geometry is organized into rooms of irregular shape. Each room
has a boundary that cannot be crossed by an occupant. Travel between two adjacent rooms is
through doors. A door that does not connect two rooms and is defined on the exterior boundary of
a room is an Exit door. There can be multiple exit doors. When an occupant enters an exit door in
SFPE mode, they are queued at the door and removed at the flow rate defined by
SFPE. Occupants that enter an exit door in reactive steering mode are removed from the
simulation immediately (Pathfinder Technical References, page 3). Occupants are defined by
physical condition of the occupant and collection of parameters for visualization of the occupant.
Occupant properties are various, with speed, delay and size as most important Pathfinder
Technical References, page 6). Path is generated as motion between two waypoints: “current” and
“next” (Pathfinder Technical References, page 7).

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2.4 Performance Based Design (Behaviours of occupants)
Path planning, steering mechanisms and collision handling are combinations which Pathfinder as a
program uses to control occupant motion. Each occupant is making a path to connect their present
position to the goal point, somewhere on the navigation mesh. This path takes charge in controlling
the route of occupants during the simulation. Occupants can change their route, if some other
factors such as collision with other occupants, but the motion of the occupants is always lead to
their chosen path. When the distance between occupant and nearest point on the path exceed a
threshold value, new path is generated in order to accommodate new situation. The main key to
behavioural modelling in Pathfinder is the path generation algorithm. In the present version of
Pathfinder, occupants can make their own course to the nearest or use specified exit, however the
framework can generate path to other goals such as preferred exits, other occupants and specific
rooms, so different behavioural options can be explored furthermore (Pathfinder Technical
Reference, page 9).
Steering Behaviour mode:
In steering system pathfinder moves occupants along their calculated paths and allows them to
respond with a change of environment. Inverse steering requires a set of projected points where
cost relative of each steering behaviour is calculated. In each second occupant is turning towards
the lowest cost steering point. Pathfinder in these situations uses a set of five vectors projecting
forward in order to divide occupants and calculate these points. Pathfinder uses three types of
steering behaviours which are seek behaviour, avoid walls behaviour and avoid occupant’s
behaviour (Pathfinder Technical References, page 9-10).
The Seek Behaviour:
Seek behaviour forces occupants to travel along the seek curve that is set, giving the location of
occupants pt0, one of the projected points pt 1 and the present seek curve (sc). The seek
behaviour is calculated by two vectors; vector leading from point pt0 to pt1 and the tangent vector
of sc. However, magnitude of the angle between these two vector is equal to the cost of seek
behaviour for pt1 (Pathfinder Technical References, page 10).

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The avoid walls behaviour:
In this type of steering behaviour occupant detects walls and steers to avoid collision with the walls.
This type of behaviour projects a moving sphere in front of the occupant in direction of the
projected point. The outlay of this behaviour is based on distance of the occupants that can travel
in direction of the projected point where occupant makes free zone away from any wall (Pathfinder
Technical References, page 10).
The avoid occupant’s behaviour:
During the simulations, this type of steering behaviour keeps comfort zone between occupant and
other surroundings simulated occupants. This behaviour first creates a list of occupants within a
frustum whose size is controlled by the velocity of the occupant. Then the behaviour projects a
moving sphere ahead of the occupant in the direction of the projected point. This sphere is tested
against another moving sphere for each nearby occupant. If none of the moving spheres collide the
cost is zero, otherwise the cost is based on how far the occupant can travel prior to the collision.
The closer this collision point, the higher the cost of the steering behaviour (Pathfinder Technical
References, page 10).
Collision Avoidance/Response
Wall and occupant behaviour will always pursuit to steer around obstacles but in some cases this
may not be always with perfect result. This issue can occur in crowded situation when occupants
cannot avoid pressure that is given from the other occupants and it will result by pressed tightly to
the walls or other occupants. When this situation occurs, additional collision is important in order to
prevent simulation to become in invalid state. Two collision handling situations can be occurred,
one of them is when more occupants collide, where second can be when occupant collide with and
obstruction set on the navigation mesh, for example wall, obstacles etc.
When collision handling is turned on, the occupant will stop at the earliest collision with either a wall
or another occupant for a given time step. If collision handling is off, the occupant will stop only at
the earliest collision with a wall (Pathfinder Technical References, page 11).

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SFPE Behaviour mode:
Pathfinder provides the option to calculate motion in an SFPE Mode. This mode implements the
flow‐based egress modelling techniques presented in the SFPE Handbook of Fire Protection
Engineering [Nelson and Mowrer, 2002] and the SFPE Engineering Guide: Human Behaviour in
Fire [SFPE, 2003]. SFPE calculations are described as a flow model, where walking speed and
flow rates of doors and corridors are defined. Three types of components can be defined in
navigation geometry of pathfinder simulator; doors, rooms and stairs. The place where occupants
walk is defined as room or open space. Stairs are defined as special rooms where speed of
occupants is limited by slopes. Doors are limitation of flow that connects rooms and stairs. In
Pathfinder corridors are not specialized type as per SFPE guide. However, corridors are modelled
as rooms with a door at the end. In this case corridors are taken into account as rooms with the
flow, controlled by doors (Pathfinder Technical References, page 13).
Collision Handling/Response
In this type of behaviour mode, there might be a chance that in scenario occupants will collide with
other occupants or walls. When collision handling is on, occupants have chance to control
collisions with walls and occupants, if it is off they will collide with walls only. Collision handling in
SFPE model is applied in two steps.
First step can occur before any movement is made for a time of step, and second occur during
movement. In pre movement step, travel velocity is pointed to force occupants to travel along the
obstructions. When there is obstruction as a wall, new velocity will make occupants to travel along
the wall. In case when obstruction is another occupant velocity will make occupant slide around the
occupant next to it. When the velocity has been adjusted around obstructions, occupants will have
new velocity for traveling. In case of moving stage, collisions are possible, but occupant in this
stage will stop at the nearest collision (Pathfinder Technical References, page 15).

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Solution Procedure
Pathfinder runs in a simulation loop that calculates movement at discrete time steps:
1. Update each occupant’s current target point.
2. Calculate each occupant’s steering velocity. .
3. Increment the current time step.
4. Move each occupant. This involves several sub‐steps:
a. Calculate the velocity for the current time.
b. If collision avoidance is turned on, detect potential collisions, and modify the desired velocity to
avoid the collisions.
c. Integrate the final velocity to find the maximum travel distance, and travel along the mesh until
this distance is reached or until the earliest collision.
5. Update output files.
(Pathfinder Technical References, page 17)
2.5 Summary
Content of the literature review is consisted from the part of the British Standards, Annex E where
designing of the shopping centres is explained in details. The same standards are used in
providing the basic layout for the simulations for this project in program Pathfinder. Standards for
designing the obstacles are also implemented in order for simulations to be as real as possible.
Beside standards and regulations, Pathfinder`s technical references are used to explain closely
how this program for simulation of evacuation of people works and it is also explained in details the
behaviours modes which are available in this program. Each behaviour mode is explained during
the literature review, from the small parts of what is the behaviour consisted of until the solution
procedures for this mode to be improved. Also, in both of the behaviour modes collision handling
and response is explained to have clear idea of how occupants are moving on the navigation mesh
of the simulator of evacuation of occupants.

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Chapter 3: Research
3.1 Introduction
The research methodology on this topic is conducted by using an agent based program simulator
in order to research the issue of impact of obstacles inside shopping centre while evacuating the
occupants including all important perimeters for evacuation that must be done in order to reduce
evacuation time and loss of life first of all, and then other perimeters which are less important in
egress process in shopping centres. In this chapter main point that will be shown are how did the
simulation of egress is represented in simulation program together with how obstacles with their
number, size and location have an impact of evacuating of occupants in shopping centre. Beside
main points, evacuation path and time will be investigated in order to take all possible information
which will be important in further investigation. Also aim of this dissertation is explained and defined
during the simulation which is used in this work.
Many productive research designs can’t be achieved without hard and tiring research strategy
which can conduct experiments, case studies or even archival analysis (Margaret, 2009). To
respond to the planned aim and objectives, and hence to explore in detail on how obstacles have
an impact during evacuation in shopping centres and what factors are affecting egress time and
behaviour of occupants a simulation has been conducted in simulation program named Pathfinder
which is used in the world as a leading egress simulator. In fact, data produced in this simulation is
fundamental for success of this research and it is important academic study of field of Fire Safety
Engineering.

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3.2 Methodology
For the purpose of this research, a layout has been designed, consisting of central corridor with its
length of 54 m, and width of 9 m (6m plus width of smallest obstacle of 3m) as required by British
Standards for designing of shopping centres (BS999, paragraph E.1.3.1, page 340). Along the
corridor, shops are set to increase reality of simulations with a number of people inside these
shops. The space is designed with loading of 600 occupants which are present at the moment of
evacuation. In order to investigate impact of obstacles, different numbers of obstacles are set in the
middle of the corridor with different sizes. Basic layout of shopping centre investigation is made
with no obstacles in order to set the initial time for safe evacuation. Considering modern tendencies
in designing of shopping centres, this investigation started with setting obstacles sized 3m x 3m,
leaving at least 6m of free space as per British Standards (BS999, paragraph E.1.3.1, page 340).
In order to find out the size of obstacles impacts occupant evacuation time, dimensions of
obstacles are raised from 3m x3m, to 4m x 4m and finally to 5m x 5m. Number of obstacles with
proposed sizes has been increased to 2, 4 and 6 and their position shifted (away and front of shop
exits) to investigate whether the density and location of obstacles has an impact during the
evacuation. As explained in Chapter 2, there are two types of occupant behaviour modes, Steering
mode and SFPE mode, and both are applied simultaneously through all simulations.

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3.3 Data
Before investigating the time for evacuation in presence of obstacles, two simulations were
conducted without obstacles in both behaviour modes just to investigate total time of egress. In
steering mode total time for evacuating with no presence of obstacles is 1 min 45 seconds, where
in SFPE behaviour mode time for evacuating 600 occupants without any obstacles is 1 min 42
seconds.
Simulation experiment no. 1: Obstacle size 3m x 3m
Investigation when obstacles are 3m x 3m, for 600 people, in Steering behaviour mode, when
obstacles are away from the exit of the shop maximum egress time for 2 obstacles available is 1
min 46 second, where if obstacles are in front of the shop egress time raises to 1 min 49 seconds.
When there are 4 obstacles, time to evacuate is 1 min 47 seconds, where if the obstacles are
positioned in front of the shop entrance time is significantly longer, so 600 occupants will need 2
min and 5 seconds to evacuate if there is 4 obstacles available. With total of 6 obstacles with same
width time to evacuate when the obstacles is away from the shop exit is 1 min 50 seconds, and if
the obstacles are in front of the shop evacuation time will be 1 min 51 seconds, which does not
have any big difference. Table 1 shows more clearly evacuation time and how much is increase or
decrease of egress time. In Annex A basic layout for this size of obstacles is show.
Table 1: Corridor width – 9m; Obstacle size – 3 x 3 m; Behaviour - Steering
No. of
obstacles
Egress time (s)
Position - away from
shop doors
Position – in front
of shop doors
Increase (s)
2 1 min 46 s 1 min 49 s 3
4 1 min 47 s 2 min 5 s 18
6 1 min 50 s 1 min 51 s 1
As it is shown from table 1, number and position of obstacles has no significant influence on the
evacuation time.

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Using SFPE behaviour mode, with obstacles 3m x 3m with the same number of occupants,
evacuation time for 2 obstacles available is 1 min 42 seconds when the obstacles are away from
the shop exits, and if the obstacles are in front of the shop the evacuation time will be same when
the obstacles are away from the shop which gives us 1 min 42 seconds. When there are 4
obstacles time for evacuation is 1 min 42 seconds when obstacles are away from the shop, where
when obstacles are in front of the shop time for evacuation is 1 min 45 seconds. With 6 obstacles
available time for evacuation when obstacles are away from the exit door is 1 min 42 seconds, and
when the obstacles are in front of shop time will stay the same which is 1 min 42 seconds. Table 2
shows complete evacuation time for this occasion when obstacles are 3m x 3m in SFPE mode.
Table 2: Corridor width – 9m; Obstacle size – 3 x 3 m; Behaviour - SFPE
No. of
obstacles
Egress time (s)
shop doors
of shop doors
Increase (s)
2 1 min 42 s 1 min 42 s 0
4 1 min 42 s 1 min 45 s 3
6 1 min 42 s 1 min 42 s 0
As it is shown form table 2, there is no significant difference in evacuation times in SFPE mode,
regardless of size, location and number of obstacles, because in SFPE mode way out for
evacuation is represented as when each occupant follows the one in front of him.
From table 1 and table 2 it is clear that number, size and location of obstacles does not have any
impact in evacuation, but only the behaviour modes which are available in pathfinder simulation
program.
Simulation experiment no. 1: neither number nor location of obstacles in both steering and SFPE
modes has no significant impact on evacuation time. This result was expected, since the layout
was set as per directives of (BS9999, paragraph E.3.1.3, page 339-340, 2008). Minor increase of
evacuation time for case set in Table 1, 4 obstacles in different positions is due to the nature of
Steering mode. Neither there is significant difference between the two modes for similar sizes of
obstructions.

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Although it is recommended to conduct the designs with a pre-set size and location of obstructions,
in real life the tenants of shopping malls are expected to allow placing of larger sized mobile
console type sale units, despite the original and approved plans. Therefore, the author decided to
investigate what would be the impact on egress time in this situation. In Annex A basic layout for
this size of obstacles is show.
As clearly shown in Table 3, in steering mode, the egress time has increased compared to the
initial size of 3mx3m. However, there is still no influence of number or position of the obstructions.
No. of
obstacles
Egress time (s)
shop doors
of shop doors
Increase (s)
2 2 min 7 s 2 min 4 s -3
4 2 min 5 s 2 min 6 s 1
6 2 min 8 s 2 min 5 s -3
So far it can be concluded that 1 meter increase of obstacle size (or 16.6% decrease of free
movement corridor) resulted with prolonged egress of 15 seconds.
In case of SFPE behaviour mode, increase of obstacle dimensions did not influence the egress
time compared to the 3 x 3 m obstructions in experiment no. 1, Table 1 (difference of +/- 2s is
insignificant). It was expected that this experiment would show increase of the RSET, The author is
of the opinion that the simulation outcome is due to the basics of the SFPE mode: evacuation is set
as a flow, where occupants follow each other with a delay required for pass of the predecessor.
No. of
obstacles
Egress time (s)
shop doors
of shop doors
Increase (s)
2 1 min 44 s 1 min 44 s 0
4 1 min 44 s 1 min 44 s 0
6 1 min 45 s 1 min 47 s 2

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Simulation experiment no. 2: increase of egress time was measurable only in Steering mode. It can
be assumed that this type of behaviour is expected as more realistic in a real case scenario. Since
the occupants of a shopping mall, by definition, are not familiar with the occupied space and it
could be expected that instead of leaving the alarmed area following the row of people ahead, they
would pass on the opposite side of the corridor which is free in the moment (or as described in
chapter 2 for Steering mode, in order to avoid collision, their waypoint of lowest cost steering point
is located on the other free side of the exit passage.
The last set of simulations has been done with the same number of people and the same
dimensions of shopping centre but obstacles size has been raised to 5m x 5m which means that
there will be only 4 m of free space to evacuate. Two types of behaviour mode are set as in
previous simulations.
In steering mode, extreme under sizing of freeways (4m exit corridor width is 33% decrease
compared to 6m as specified in (BS9999, paragraph E.3.1.3, page 340, 2008), resulted with
additional 30s of egress time. The change of egress time has doubled for an additional 1m of
obstacle increase. In Annex A basic layout for this size of obstacles is shown.
No. of
obstacles
Egress time (s)
shop doors
of shop doors
Increase (s)
2 2 min 36 s 2 min 29 s -7
4 2 min 36 s 2 min 34 s -2
6 2 min 43 s 2 min 43 s 0
Similar to the outcome of experiment no.2, for SFPE mode there were only minor changes of the
egress time. It is clear that due to the initial theoretical settings of the SFPE mode, the simulation
results would repeat even for further expand of the obstructions. This means that SFPE mode will
possibly deviate from an expected outcome in a real situation, despite of the experiment results
(assuming that all other fire safety items remain unchanged).

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No. of
obstacles
Egress time (s)
shop doors
of shop doors
Increase (s)
2 1 min 44 s 1 min 45 s 1
4 1 min 46 s 1 min 45 s -1
6 1 min 49 s 1 min 49 s 0
3.4 Analysis and Discussion
Main purpose of this study is to investigate impact of different sizes of obstacles in shopping centre
and how obstacles have an impact on evacuation time. This study was conducted in program
which is used for simulation software for evacuation of occupants in any designed object. In this
research one area of an imaginary shopping centre (main corridor and adjacent shopping units)
was designed, applying basic British Standards (BS: 9999. Appendix E, page 339, 2008)
recommendations for width of corridors in similar areas and utilities Choosing to create one specific
area, allowed the Author to achieve most realistic scenario and to eliminate those space factors
which are not relevant to the subject of the Research. Simulations experiments were conducted by
creating multiple scenarios, where number, position and size of the obstacles were subject of
variations. In addition, two types of occupant behaviour modes were applied Steering & SFPE.
In steering mode, the calculations and path generation are calculated based on the choice of the
“lowest cost steering point
Tables’ 1 – 6 show results of different simulation scenarios, where each table shows calculated
egress times with respectively increased obstacle dimensions and behaviour modes.
It is obvious that for the designed size of shops and corridor, changes in number and distribution of
obstacles do not result with significant differences. This proves that occupants shall use the
available free space between the shops and obstacles, and that density and location do not
influence the ASET. However, it has to be noted that the density in particular shops is predefined
as per recommendation of the Approved Document B (ADB, Appendix C, Methods of
measurement, page 135, 2006), and further simulations could be done with overloading with
occupants.

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For the purpose of the results’ analysis, the author found that comparison of results by behaviour
modes and obstacle sizes would be of interest.
Table 7 below shows the comparison of the simulation outcome:
Table 7: Egress time comparison for different behaviour modes, Corridor width – 9m; 4 nos.
of obstacles, position away from shop doors
Size of
obstacles
Egress time (s)
Steering mode SFPE mode
3 x 3 m 1 min 47 s 1 min 42 s
4 x 4 m 2 min 05 s 1 min 44 s
5 x 5 m 2 min 36 s 1 min 46 s
For same design, number and location of obstacles, the simulation is showing different results for
each of the modes. In further researches, choice of options for occupant motion should be carefully
considered.
In SFPE mode (Thunderhead Technical reference, page 13) the only obstacle are the doors, and
occupants are evacuated to the predefined exits (as designed and in evacuation plans) in a flow.
There are no restrictions on overlapping occupants.
In steering mode (Thunderhead Technical reference, page 9), occupants are allowed to make a
choice for their next waypoint, where the software model calculates waypoints of “lowest cost” and
next points are recalculated each time. Lowest cost is calculation is predetermined by the: seek,
avoid walls and avoid occupant’s modes behaviours, where each takes into consideration size of
physical comfort zones (which can be adjusted for the purpose of simulations).
Pathfinder’s typical case (IMO Test 10, Technical reference, Thunderhead, p. 1-2) is set to show
only the basics of the two available options for occupant motions. There are no obstacles in the
typical case. When placing obstacles in high density areas, where the occupants are not familiar
with the building and escape plans / routes. Steering mode allows each occupant to recalculate his
route after passing by any of the obstructions. The previous results with an (expected) occupant
behaviour, where people shall each time choose between two available sides of escape corridors,
and by shifting eventually increasing the length of their escape route (similar behaviour is common
in vehicle transport, lane shifting on congested roads).

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During the design phase, it is of ultimate importance to predetermine the real expected occupancy
in peak periods (e.g. weekends, holidays, etc.), as well as sizes, numbers and positions of the
obstacles. These must be clearly marked as fixed items in emergency and evacuation plans, and
further enlargement of any parameters must be prohibited.
For such areas (predetermined obstructions), one could consider specific application and design
for positions of warnings, exit route lights, emergency lights, floor exit indicators etc. None of these
items are included in the evacuation software occupant motion models, but they could direct the
occupants to enter in the SFPE mode. For example, one set of exit lights are usually installed in the
middle of the corridor, where placing two parallel sets over each of free escape lanes would have
an effect. Bottom of obstacles (mobile or fixed) could be equipped with emergency lights, arrows
showing towards lanes.
3.5 Summary
Present designed partial area of a shopping mall (simple corridor with adjacent shops and one
escape route, assumed number of occupants) is used for the simulations investigating influence of
obstacles on the egress time form the area.
Several scenarios each with different number, position and size of obstructions were tested in both
Steering and SFPE mode of occupant motions.
Number and position of obstacles have shown no influence on the egress time. On the other hand,
as expected, increased evacuation time is proportional to the size of obstacles.
Simulation results have shown that for different for behaviour modes, egress time differs
significantly for different sizes of obstacles. These points to the importance of proper choice and
application of human behaviour assumptions for the occupancies subject of experiments.
The results also indicate the importance of determining of size, location and nature of obstacles
during the design phase and evacuation plans, without allowance of latter increase.

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Chapter 4: Conclusion and Recommendation
4.1 Introduction
The aim of this dissertation was to investigate impact of obstacles in shopping centre in case of fire
using the program for evacuation Pathfinder. Different methods were conducted during the
research about the impact of obstacles in shopping centres, but the method which gave the most
results was a program for simulation of evacuation. The objectives were to analyse if current
standards and regulations in accordance of new tendencies of shopping centres designs, to
determine impact of size and location of obstacles on egress time using Pathfinder modelling
software and to investigate the impact of different models of human behaviour based on simulation
experiment results.
Current applicable standards recognize standard shopping centre areas, where the single corridor,
single level designs is considered as a dominant choice of the architects. In this case, the corridor
is often an escape route at the same time and the basic recommendations are either to eliminate
any obstacles, or if this is not the case, to widen the corridors for the width of the expected
obstruction. New trends of large multilevel open areas are not recognized nor standardised. The
author created one layout, which is initially in accordance with BS9999:2008 recommendations and
represents partial are a typical shopping centre corridor, occupied with obstructions and serving at
the same time as evacuation route. Subject of simulation experiments were different number,
location and sizes of the obstacles, as well as comparison of two different behaviour modes
available in the software modelling.

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4.2 Conclusion
Based on the research conducted in this study, main conclusion may be as follows:
 Current standards recognize obstruction in shopping centres only in corridor areas, and no
regulations are developed for the modern trended open areas with the variety of different
types of obstacles. The conducted simulations did not comply with the recommendations given
for corridor type of shopping centres.
 Recommendations for Atrium areas escape route design are general and do take into
consideration any obstruction. Atrium areas (BS9999, Annex B, page 262), exclude malls in
shopping centres.
 Many of the previous similar researches deal mostly with different behaviour models/software
algorithms, where obstacles are only part of the scenarios. It seems that particular influence of
obstruction located on the escape routes is not studied. Usually is just stated that the
obstacles do have influence on evacuation time, but the levels of this influence are not
calculated or investigated.
This research used a corridor type escape route and simulations have shown the following:
 Number of obstacles doesn’t not have any influence on the RSET.
 Location of obstacles (as long as they are distributed in one line) does not increase the
evacuation time (even when all obstructions are located in front of the shops).
 Different behaviour modes do provide largely different results, confirming that proper choice of
escape algorithm needs to be careful selected prior to simulation experiments.

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4.3 Recommendations for Further Research
This research has involved conducting an investigation of impact of obstacles in shopping centre
during the fire using Pathfinder with a literature review that supported designing of corridor in
shopping centre to establish the background of investigation. The conducted Pathfinder simulations
were efficient in solving the aim of this investigation. Based on the conclusion given in point 4.2 the
following is recommended in further research of this area of interest:
 to investigate expected human behaviour during evacuation from shopping complexes, where
current occupants are not familiar with the escape plans
 Following modern design trends, development of legislative for “atrium” type shopping centres
(congested with series of various obstructions) should be considered
 Investigate and determine specific recommendations for emergency evacuation signs (e.g.
shifting of warnings, exit route lights, emergency lights, floor exit indicators from centre line of
corridors to both escape passages; not allowing obstacles and exit doors to remain in the
same axis line)

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Annex A
Basic layout for shopping centre with obstacles size 3m x 3m.

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References:
1. “The Building regulations 2010, Fire Safety, Approved Document B, Volume 2, Buildings other
than dwelling houses, 2013”
2. BS9999 “Code of practice for fire safety in the design, management and use of buildings”,
2008.
3. D. Helbing, L. Buzna, A. Johansson, T. Werner, Self-organized pedestrian crowd dynamics:
experiments, simulations, and design solutions, Transportation Science, 39 (2005), pp. 1–24.
4. A. Kirchner, K. Nishinari, A. Schadschneider, Friction effects and clogging in a cellular
automaton model for pedestrian dynamics, Physical Review E, 67 (2003), p. 056122
5. D. Parisi, C. Dorso, Microscopic dynamics of pedestrian evacuation, Physica A, 354 (2005),
pp. 606–618
6. Kevin McGrattan, Bryan Klein, Simo Hastikka, and Jason Floyd. Fire Dynamics Simulator
(Version 5) User's Guide. July, 2007. NIST Building and Fire Research Laboratory.
Gaithersburg Maryland USA . NIST Special Publication 1019‐5, 2007
7. Nelson, H. E., and Mowrer, F. W. "Emergency Movement." The SFPE Handbook of Fire
Protection Engineering Ed. DiNenno, P., and Walton, D. W. National Fire Protection
Association 2002. 3‐367 ‐ 3‐380, 2002.
8. BS 7974:2001, Application of fire safety engineering principles to the design of buildings.
Code of practice, 2001.
9. Xie, R, Simulation of Optimized Evacuation Processes in Complex Buildings Using Cellular
Automata Model, 2011.
10. Xie, R, Simulation of Optimized Evacuation Processes in Complex Buildings Using Cellular
Automata Model 2014
11. Wang, Z, PUBLIC EVACUATION PROCESS MODELING AND SIMULATION BASED ON
CELLULAR AUTOMATA, 2013.

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