Event planning guide

It is important for Event Organisers to understand what type of audience they will attract to their event, in order that they may fully understand how to manage that crowd.

A Community event with stalls catering and small smaller fairground rides is likely to attract a mainly family audience and this would pose a relatively low risk. Should as an organiser you then choose to introduce larger fairground rides, open later and permit the sale of alcohol then this would completely change the audience profile and as such the staffing required and possibly increase the risk of antisocial behaviour.

Calculating capacities

It is very important that event organisers understand how to work out the coverall safe capacity of a

their site. First you need to calculate the holding capacity and then the emergency evacuation capacity and whichever figure is the lower will then be set as the overall site capacity.

Holding Capacity

A crowd is classed as being unstable when it reaches a capacity of >4 persons per square metre. This increases the possibility of dangerous circumstances such progressive crowd collapse and crushing leading to major injuries, so for open air events best practice is to use a figure of 2 persons per square metre to create the calculation.

For example: If the event site was approximately 1450m2, but after the installation of event infrastructure the area left as accessible to the public is 1150m2.  This would mean using the figures above that the holding capacity of the site would be 4600 people.

Emergency Egress Capacity (Exit times)

The guideline exit time for this event based on the 'Fire Safety Risk Assessment, open air events and venues' is less than 10 minutes.  Normal flow rates as prescribed by the Emergency Planning College are 82 persons per minute per metre of exit width. If however your audience is primarily older people then you may be advised to reduce the flow rate to 75 persons per metre

You then need to look at your available exit points, if the site has say 2 exits each of 3m, giving a total exit space of 6m the calculation would be:

Persons per metre per minute x amount of exit space in metres x maximum permitted exit time

Which for this example would be?

75 x 6 x 9.99 = 4495

It is however best practice to assume that you may lose one of your exits as this may be the site of the incident which in this case would change the calculation to:

75 x 3 x 9.99 = 2247

This would safe capacity for the site of 2247 persons

Crowd dynamics model