Crowd Density

Considerations

So what does crowd dynamics mean to you?

Crowd - ‘a large number of people gathered

together’ (on line dictionary)

Dynamics – ‘the branch of mechanics that deals

with the motion and equilibrium of systems under

the action of forces’

Is this helping?

Alternatively

Crowd dynamics can be defined as the study of how

and where crowds form and move above the

critical density of more than one person per square

metre. At high density there is the potential for

overcrowding and personal injury. It is therefore

important to understand the dynamics of crowds,

how crowds understand and interpret information

systems, how management systems affect crowd

behaviour. We call this the science of crowd

dynamics.

Prof.Dr. G.K. Still PhD Thesis

So the key elements are

The science of how/where crowds form and move

How/where it reaches critical mass (1 person per

m2)

Safety limits

‒ Design Effects

‒ Queueing

Crowd Density

‒ Crush Potential

Flow Rates

‒ Egress - Normal and Emergency

Prof.Dr. G.K. Still

So why do ‘accidents’ occur?

Lack of understanding of crowd dynamics/behaviour

Lack of attention to crowd densities and movement

Negligence

Complacency

The late Jonathon D Sime, following his review

of a number of crowd ‘disasters’, concluded:

‘Communications systems (Control Centre, CCTV,

and public address) have to be integrated with

safety aspects of:

Architectural Design

Information Technology

Management

Buildings in Use (a thorough understanding of

how to comprehend and use complex settings)’

How can this be applied in practice?

Arrival – the travel arrangements of the spectators

and how these need to be considered

Ingress – upon arrival at the venue/sports ground,

the ingress of spectators must be efficiently

managed

Movement – once inside the sports ground, the

way in which the crowd moves around the ground

can influence the management plan

Exit/Egress – upon termination of the event,

whether planned or unplanned, the movement of

the crowd needs to be managed

Dispersal – post-event travel arrangements and

the movement of the crowd away from the event

must be considered

Assessing crowd related risks:

Ingress

Getting in – queueing, barrier design, information,

management, flow rates, arrival profiles

Circulation

Moving around – queuing, design, information/

signage, management

Egress

Getting out under normal and emergency

arrangements - flow rates, egress times, departure

profiles/[patterns

Emergency egress (during ingress, circulation and

normal egress)

Prof.Dr. G.K. Still

Three primary tools of crowd management

Design

‒ Numbers and capacities of turnstiles/ingress system(s),

constraints, queuing, segregation systems, barriers, locations

for concessions, toilets, seating, rake of stands etc

‒ Normal and emergency conditions

Information

‒ Signage, communication systems, information on tickets, on-

line advice, face to face, lighting

‒ Normal and emergency conditions

Management

‒ Processes, procedures, communication structures

‒ Command/management structures

‒ Stewarding and policing arrangements

‒ Normal and emergency conditions

Prof.Dr. G.K. Still

An approach to planning

NORMAL INGRESS CIRCULATION EGRESS

DESIGN

INFORMATION

MANAGEMENT

EMERGENCY INGRESS CIRCULATION EGRESS

DESIGN

INFORMATION

MANAGEMENT

And finally four S points to consider

Short cuts

The Crowd WILL exploit ALL short cuts

Sightlines

Operational sightlines can be deceptive

Spaces

Not all spaces are used evenly

Speeds

At high density the crowd moves at the pace of the

slowest individuals.

Prof.Dr G.K. Still

Who is responsible for calculating the

capacity for an event?

The objective of the Guide is to provide guidance to ground

management, technical specialists such as architects and

engineers, and representatives of all relevant authorities, in

order to assist them in the assessment of how many

spectators can be safely accommodated within a sports

ground.

Green Guide 1.3

Responsibility for the safety of spectators lies at all times with

the ground safety management. That management will

normally be either the owner or lessee of the ground, who

may not necessarily be the promoter of the event.

Green Guide 1.4

What factors would you consider relevant in determining

an appropriate standing density at an event?

Type of event

Duration of event

Dynamic of crowd (dancing/static etc)

Nature of surface (concrete, mud etc)

Slopes, steps etc

Profile of audience (height, size, families etc)

Lines of sight

Bags, and equipment

Safety management

P & S factors

Barrier plans

Space for movement

Egress and evacuation

This list is not intended to be exhaustive

P & S Factors

‘P’ Factor – an assessment of the physical

condition of viewing accommodation

‘S’ Factor – an assessment of the Safety

Management of that area

Assessment should be given a numerical value

between 0.0 -1.0

‒ e.g. good physical condition or safety

management = 1.0 really poor = 0.0

‒ area with capacity of 5000 where P or S factor

of 0.5 applies will be restricted to 2500.

Progressive Crowd Collapse

Crowd related incidents are often described as

crushes/stampedes

This can imply that the crowd are to blame

whereas causation can probably be attributed to

design/information/management failures

Typically the cause of death is restrictive asphyxia

caused by progressive crowd collapse

These can occur in high density/low stability

crowds

What key guidance may be applicable to

occupant densities?

Event Safety Guide

‒ ‘Generally 0.5m2 of available floor space per person is used for outdoor music events

Guide to Safety at Sports Grounds

‒ For the purpose of calculating the capacity of standing areas at sports ground, the maximum number that can be applied is 47 persons per 10 square metres

‒ In the case of seats, this will be determined by the actual number of seats, less any that cannot be used safely (owing to restricted views or their inadequate condition) and an assessment of the (P) and (S) factors)

‒ …it should be noted that research indicates that spectators can only circulate freely when crowds are no denser than approximately 10-15 persons per 10 square metres

What key guidance may be applicable to

occupant densities?

Fire Safety Risk Assessment (Open Air Events

and Venues)

‒ Standing spectator/audience area or bar – 0.3m2

‒ Assembly area, dance floor or hall – 0.5m2

‒ Dining area, seated bar or restaurant – 1.0m2

‒ Skating rink or sports area – 2.0m2

‒ Display gallery or workshop – 5.0m2

‒ Camping area – 6.0m2

‒ Sales area – 2.0m2

‒ Car park – 2 persons per parking space

So how do you decide?

Appropriate density figures must be agreed on a

risk assessed basis carried out by a competent

person and be bespoke for the event.

This may be based upon a zoned arrangement

(i.e. different from sector to sector)

So how can it go wrong?

Background

8 December 2008 fans are hurt in

‘stampede’ outside Fairfield Halls

Croydon awaiting the arrival of JLS.

The group were appearing in X

Factor at the time.

9 December 2008 JLS apologise and

state they want to play another gig at

the venue for those who missed the

previous appearance.

30 October 2009 severe

overcrowding when JLS attend

Christmas Lights turn on at Trafford

Centre, Manchester.

‒ An estimated 120,000 visitors

attended during the day with

gridlock of road network. Doors

had to be locked with thousands

locked out.

Line up including:

Alexander Burke

Calvin Harris

Girl’s Can’t Catch

JLS

Little Boots

Mini Viva

Natalie Imbrugia

Noisettes

Pixie Lott

Sugababes

Taio Cruz

The Saturdays

Tinchy Stryder

Background

• Event is free and unticketed

• Show commences 2pm on

Saturday 14 November 2009

• Big lights turn on scheduled for

7.30pm

• JLS No 1 in charts

• Accepting we have the benefit

of 20/20 hindsight what would

your assumptions be in terms of

potential numbers attending?

What really happened?

Planning for about 5000 spectators

Estimates suggest about 27,000 turned up

Those who are not admitted are contained behind

drag barriers/heras fencing

Clustering front of stage means space is visible to

rear of arena

Sugababes due on stage

Seeing this some of overspill of spectators start to

climb over barriers. Others put pressure on barriers

which collapse

About 60 injured and real potential for fatalities

Event cancelled

How could ICE/DIM approach have helped?

Key issues

‒ Accuracy of assessment on numbers attending (learning

from Croydon/Trafford Centre

‒ Monitoring of build up – early warning/fill prediction

‒ Counting of admissions

‒ Planning for excess numbers (big screen?)

‒ Appropriateness of barriers, would screening have helped

‒ Poor management/planning?

‒ No plan B

‒ Communication strategy

‒ Free and unticketed, would ticketing have helped?

‒ Inadequate numbers of stewards