Introduction
The DIM-ALICED Model is an enhanced model of the DIM-ICE Meta Model used by its founder Professor Keith Still, Keith is a professor in crowd science, and widely regarded as the industry leader in the subject. Andy Hollinson from the Crowd Safety Training Group, and his team expanded on this to create the DIM-ALICED Model.
Design
Information
Management
Arrival
Last-Mile
Ingress
Circulation
Egress
Dispersal
Capacity Calculations
The capacity of a venue should not be driven by a venue, or promoters need to sell tickets in mass numbers, nor driven by guesswork, previous events, or previous experience of the same event in another country. The capacity of a venue is dictated by both understanding of the event space, the guest groups expected the geography and several other factors. This must be carried out by a qualified company, or individual, with the ability and experience to calculate the realistic number of persons that can safely be accommodated within an event space.
The Space
As mentioned above, you must first understand the type of event, the crowd expected, the artist performing, the conditions, location, geography, weather, and the actual space that can be used by the guests, often called viewing areas, toilets, stairs, and corridors should not be considered ‘’usable’’ space.
When calculating capacity, ensure that allowance is made for areas taken up by facilities such as food and merchandising stalls, temporary structures, and stairways. Areas where there is no easy access to view the main stage or attraction, should also be identified, such as toilets, stairways, and corridors (Managing Crowds Safely, HSG154 2nd Edition).
Calculation
Upon defining a figure, this must be timed by two, for example, you have established your event space, with all unusable space discounted, the global best practice suggests that the calculation should be based on 2 persons per m2.
Note, for a moving queueing system the guidance states 4 people per m2. The guidance (UK Green Guide - Guide to Safety at Sports Grounds) states 4.7 people per m2 for standing viewing areas, however several factors must be considered, such as physical attributes of the crowd, hence why understanding your event, and demographic of guests are paramount, 5 people per m2 is considered high-risk.
Emergency Egress
Evacuation of a venue must involve input from emergency services, in the below example we have provided a calculation based on the above numbers, and best practice. The Green Guide advises that 8 minutes is the maximum time for an emergency egress of a stadium, this is commonly adopted globally, and the best practice we at SABRE Risk adopt.
It should be noted, that for site deemed as ‘’green field’’ such as outdoor festivals, or other open field events, emergency egress should take no-longer than 15 minutes, but all persons must be evacuated to a place to relative safety in 8 minutes or less.
Places of Relative Safety
It is often necessary to devise a temporary place of safety, such as when evacuating large sites. This may be defined as a place of relative safety and includes any place that puts an effective barrier between the persons moving away from danger, this might be internal LAP (Local Assembly Point).
The Green Guide indicates that 82 persons per minutes can be evacuated through a 1 metre opening, based on this, a calculation must be made to identify the space required to evacuate a venue with a 30,000-person capacity.
30,000 ÷ 82 = 366 metres if you intend on evacuating in one minute.
366 metres ÷ 8 = 46 metres if you intend on evacuating a space within the 8-minute best practice guideline.
The above calculation indicates that your site will require 46 metres, or more, to evacuate 30,000 people in 8 minutes.
Our main gate has 40m of usable space, with screening equipment, however, in the event of a major incident at this location, for example large technical fire, or IED detonation, the gate has been discounted, as it cannot be used. We have five other gates, totalling a width of 55m, this provides us with the below.
(Discounted) Main Gate (40m width, has screening equipment, so figure decreased from 82 to 70 persons per minute), 40 x 70 x 8 = 22,400 persons under emergency evacuation conditions (8 minutes).
(Can Use) Other Gates (55m width in total, has no screening equipment, figure remains at 82), 55 x 82 x 8 = 36,080 persons under emergency evacuation conditions (8 minutes).
The below enables us to calculate a total of 36,080 people can egress through 55m of usable space in 8 minutes, as these locations have no screening equipment, the main gate has been discounted from our calculation as this is our largest gate, where people generally egress through.
Our venue has a capacity of 30,000 people, the remaining 6,080 allowance means that an evacuation will likely occur in under 8 minutes, but we must not assume this to be the case.
Why?...
Other Considerations
If search and screening equipment is present at multiple entry/exit locations, then the calculation must be reduced from 82 persons to 70 persons per minute, which will increase the space required for an emergency egress. In an emergency egress scenario, it is unlikely screening equipment can be, or will be removed, an incident can arise at anytime, anywhere, hence why appropriate emergency exit gates must be factored into your overall site plan, without obstruction, as egressing people through areas where others might still be queuing (search and screening) would not be practical, nor safe.
Your event is in an outdoor arena, your event has been subjected to adverse weather for the past three days, on the third day, you have the headline talent on stage, you are expecting peak visitation, the weather has caused the ground to turn to mud, and large clusters of water are present, how will this impact emergency egress, and egress in general? The speed of egress in general will likely be slower, areas might be unusable, unless measures have been put in place to harden the ground.
Conclusion
Although primarily aimed at organisers who have overall responsibility of an event, it should be noted that all stakeholders have a responsibility to ensure a safe event, people should raise concerns, and take an all-inclusive approach with planning. There is potential for minor or major injury occurring through the dynamics of crowd behaviour, as past tragedies have demonstrated. Measures should be taken by the organisers to ensure that they have engaged qualified, reputable, and professional crowd safety management services.
Crowding occurs because of an excessively large number of people gathering in a specified area. Large numbers gather routinely in such places as train stations, and airports. However, they also gather, often in greater density at sporting events, concerts, and festivals. It is at these locations where the safety of persons is at greater risk, dependant on several factors, such as profile of the event, and size.
Good planning from an early stage will help you run your event safely. You need to allow sufficient time to gather information, consult and obtain advice and put in place effective controls to manage crowd safety. The safe running of your event should be given equal priority to other business aims, if not higher.
It is important to involve staff representing different facets of the event, representatives of relevant outside bodies, such as local authorities and emergency services, should be brought into the planning process. To minimise the risk of overcrowding, you need to consider the activities, movement, and dynamics of a crowd at various locations and times within a venue, this can be done using the RAMP Analysis and the Mapping of Risk, a modelling tool which focuses on Routes, Areas, Movement, and Profile, more on this in the future.
Contact Us
To find out how SABRE Risk can support you, and your event, please contact us to discuss your requirements in confidence.
operations@sabre-risk.com
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