Modelling and Managing Crowd Behaviour

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Modelling and Managing Crowd Behaviour

• Prof. Dr. G. Keith Still FIMA
• Easingwold February 2008

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Contents of this talk

• Crowd Dynamics
• DIM-ICE
• Models and Simulations
• Large Scale Multi-Building Evacuation
• Communicating with the Crowd
• Canary Wharf Project
• Summary and Conclusions

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1. Crowd Dynamics

• Design Information Management
• Ingress Circulation - Egress

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Three phases of Crowd Dynamics

• Ingress
• Arrival profile and flow rates
• Assessing the design capacity/constraints
• Signage/communication system
• Circulation
• Facilities planning and management
• Signage/communication systems
• Egress
• Normal and emergency
• Signage/communication systems

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DIM ICE model for Crowd Dynamics
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Simulation of doorway entrance
The addition of a central handrail changes the
dynamics of the crowd This can INCREASE flow rate
through the door by between 35 -
70..... Small change in the design and we have a
significant change in the flow rate
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Flow Rates NOT constant

• As DENSITY increases FLOW RATE will increase THEN
  decrease
• As the crowd density approaches the critical
  values of 3-4 people per square metre the flow
  rate drops
• This is critical in designing emergency egress
  routes.
• At high density the crowd moves at the speeds of
  the slowest group in the crowd
• Simulations need to reflect this

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2. Models and Simulations

• Since 9-11 literally hundreds of emergency
  evacuation models, simulations and tools have
  appeared on the market.
• Some good, some bad, some downright dangerous.

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Modelling for crowd safety

• Someone who builds a mathematical model can get
  carried away with all the clever things that can
  be done with it.
• The model becomes a safe little world, free from
  anxiety, free from office politics, rewarding in
  its own right.
• This often results in a very clever model that
  has little to do with reality.
• Resist the temptation to be too smart in building
  a model. Take small model building steps
  interspersed with healthy doses of reality.
• Sam. L Savage. Author of Insight.XLA - Analysis
  software.

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Dont let simulations fool you

• Watch the next two video clips of commercial
  evacuation software.

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Simulation 1. Steps
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Simulation 2. Simulex
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Discussion 1

• Discuss the pros and cons of the last two
  simulations

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Models help us test the design dynamics

• We build a model to discover the properties of a
  system
• With discovery comes understanding
• With understanding comes control

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Mathematical Modelling Tools

• Spatial Analysis
• Visibility Graph Analysis
• Spatial and temporal invariants
• Network Analysis
• Optimisation - Min/Max Flows
• Tours, shortest spanning trees, etc.
• Agent Based Analysis
• Emergent Behaviour
• Sematectonic Stigmergy change in state, result
  of task-related action, progressive crowd collapse

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DCMS Persistent Standing
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Progressive Crowd Collapse
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Large ScaleMulti-Building Evacuation

• Consider the elements of evacuation and business
  continuity for a large scale, multi-site,
  multi-building evacuation,

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World Trade Centre - 2001

• Twin Towers
• 9 Million Sq. Ft.
• 110-story Buildings
• 50,000 employees
• 80,000 daily visitors
• 104 Elevators
• 9 building evacuations

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16 Acres of devastation
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Precision Attack multi-building evacuation
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Project Canary Wharf

• London Financial District
• 90,000 residents
• Island within city of London complex space

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Canary Wharf CBD
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4 Egress Scenarios post 9/11

• Total Evacuation
• Fire (GTFOH)
• Directed Evacuation
• Bomb threat
• Phased
• Decontamination
• Stay Put
• External threat (Biological, Chemical,
  Radiological, Gunman, Security alert, Car bomb.)

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Consider the location of safe refuge areas
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Discussion 2

• What are the key elements in defining a
  multi-building evacuation?
• Where would models help us understand the crowd
  dynamics and evacuation strategy?

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Note centralised assembly points
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Evacuation in stages

• Floor to safe passage (stairs)
• Stairs to ground floor
• Ground floor to streets
• Multi-building street evacuation

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Possible Strategic Responses
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Evacuation Strategies
Analysis
Planning
Implementation
Consulting
Strategic detailedanalysis
Scenario Planning
Training Mgrs
Training Individuals
Data capture
Tools Software
Communication decision support e.g.,
Evacuation tool
Evacuation Tool
Spreadsheets Myriad
Spreadsheets Myriad
Spreadsheets
Canary Wharf the UK Financial District
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Network Diagram
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Capacity Analysis

• Bottleneck analysis
• North 17m
• East 19m
• South 27m
• West 37m
• Total 100m
• 82 people per metre per minute

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Egress Capacity 100m 8,200 ppm
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The estate has sufficient capacity (roads)
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Passes Rough Cut Modelling

• Now we drill deeper into the problem
• Are there other limits to egress?

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Simulating egress - choice of four exits
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Clearing a floor
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Stair Egress - considered as safe

• Data shows stairway congestion problems
• Precedence behaviour
• People stopping to rest
• How fit is the population?
• First responders trying to gain access while
  egress is in progress
• 15 story building
• 9 minutes to descend stairs
• First responders could be on site in 5 minutes

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Are there other site limits?

• Which route would the public choose?
• Are there any areas that give rise to potential
  crushing?

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Egress is directional

• Colours show allocation to each exit
• In the event of an incident egress away from the
  incident is still divergent, unidirectional and
  avoids cross-flows

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Simulations problem spotter

• What do the above images tell us about the crowd
  dynamics?
• What do we need to do to keep this crowd safe?

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Unplanned Egress
Dangerous bottlenecks at the Station Approach
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Evacuation Strategies
Analysis of complex spaces and behavioural based
safety
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50,000 copies deployed
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Crowd movements

• In large areas how quickly can the crowd
  disperse?
• Using GIS systems we can map mass migrations

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London resident population densities
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Walk-time information is available
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4. Crowd Communications

• How do we get the crowd to START to move
• Information systems, communication strategies.

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"The chief virtue that language can have is
clearness, and nothing detracts from it so much
as the use of unfamiliar words."Hippocrates
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Four Seasons Hotel (Channel 2)

• Do not, under any circumstances, use the
  elevators
• Many people evacuated from the World Trade centre
  used the elevators
• Stay Put. You will be advised as to what
  procedures to undertake
• Communication problems
• Do not open windows - a sudden surge of fresh
  air will create a vacuum which will attract fire.

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Jargon is not good communication

• Hillsborough / Centennial Park
• Silver Control / Orange Car Park
• Ambulance ... loading point / rendezvous point /
  pickup point
• Left / Right
• Main Entrance / Inner Concourse / Main Stage
• DS1 / 19 North Promenade / HSBC Building

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Initial stages of a disaster

• Chaotic, confusion, media reports confused
• What happened?
• Where did it happen?
• What do I do?
• Where do I go?
• What next?

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Do crowds always panic?

• How the crowd reacts depends on a number of
  critical factors.

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Behaviour described as panic

• People do not use nearest emergency exit
• escape via way in
• May not use emergency exits at all
• not noticed
• unfamiliar location
• Frantic escape activity

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Panic happens when people are

• Trapped
• exit blocked
• late evacuation
• Disoriented
• building collapse/capsize
• dark/smoke filled environment
• Isolated from others
• family/friends

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But panic.

• Is not inevitable
• Is an individual response
• Is rare in emergencies
• Can be mitigated
• Discuss how we can mitigate panic in the built
  and complex environment

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May 18th Panorama BBC
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Crowd Dynamics - technical advisors

• It would take some time to realise this was a
  simultaneous attack
• Total failure of the London Underground Network
• City Wide problem with traffic
• Massive Grid Lock
• Multi-site evacuation
• Canary Wharf no transport off the island
• Short term impact on public confidence in the
  system
• Potential for the crowd to be overreactive

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Discussion 3

• Do we address these factors in current planning?
• Could we improve our evacuation strategies?

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5. Summary and Conclusions
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Phases and Controls

• Three phases of Crowd Behaviour
• Ingress Circulation Egress
• Three influences of Crowd Dynamics
• Design Information Management
• Modelling helps
• Discovery Understanding Control

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Foresight NOT Hindsight