Crowd Density Considerations So What Does Crowd Dynamics Mean to You?
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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. Background Line up including: Alexander Burke • Event is free and unticketed Calvin Harris Girl’s Can’t Catch • Show commences 2pm on JLS Saturday 14 November 2009 Little Boots • Big lights turn on scheduled for Mini Viva 7.30pm Natalie Imbrugia • JLS No 1 in charts Noisettes • Accepting we have the benefit Pixie Lott of 20/20 hindsight what would Sugababes your assumptions be in terms of Taio Cruz potential numbers attending? The Saturdays Tinchy Stryder 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 .