The delusion of egress planning- were plans do not match reality


In the past years, we spent a fair bit of time looking at the ingress process at events and attempted to bring a more realistic vision to the planning for this process. Our initial thoughts were to challenge what was already in place; stress test it and see what worked and what did not. The findings have assisted us during planning to provide a more representative calculation and more precise timeline.

Out with this, sitting in the back of our heads was can the same be done for Egress? During planning, we will look at exit width, flow rates, capacities and necessities for evacuation due to fire and that will give us an egress time. So many documents out there with these calculated times, possibly with no thought of how can the maths be wrong.

The word that seemed always crop up for us was, efficiency.

Do all systems work at 100% efficiency; no flaws, no drop off or influencing factors? Do we delude ourselves during this planning for egress, as it may not provide the answer we need? That answer may determine the capacity of an event and with that ticket sales; the likelihood of loss of revenue is a great reason to act like the 3 monkeys when planning.

To contemplate were a drop of would transpire, first we had to hypothesis the perfect scenario.


Flat, clean surface. No damage of this surface. Suitable to allow smooth passage. Exit width would not impede or narrow the egress route. Pedestrians would continue to walk clear of exit without pausing, waiting or slowing. It would be dry and good temperature. Lighting conditions would not create shadows or impede vision. Everyone would be the same height, weight, age, sex, dressed the same, identical footwear, no bags, walk at the same speed and stride length (basically clones of one another). Everyone would have the same thought process and goals. No one would have taken alcohol, drugs or mind altering substances that could alter thought process.

That is where we started. We see this as the ideal environment and occupants. The next thought was, everything that changes from this can influence the egress efficiency. Let’s look at a scenario of a music festival (we are painting a site in our mind, but based on observations)

We are in a grass field (to consider – is it flat? How long is the glass? Are there holes in the field, hedges, dirt trails?) We are in England during the summer (to consider – what time does the sun set? When does, egress start? Will it be dark? Do we have artificial light? Does this provide an even spread of light without dark patches? What is the weather like? Is it raining? Is there mud? Is there standing water?) What type of audience will it attract? (to consider –are there family’s? Are there children? Are there more males that females? The average stride length in the UK? Average age range of customers?) Do the customers consume alcohol or drugs? – (to consider – the volume of drink consumed per customer? What type of drugs may they take?) Exits – (to consider – distance to exits? How many exits are there? Are exits spread out of all in the one location? Are the bars and entertainment still open during egress? Is the signage and information on exiting clear? Is transport plan robust and well known?)


That is a few of the things that may influence the efficiency of an egress. But, can we accurately define the percentage of drop off from being 100% efficient. We doubt that it would be possible to precisely achieve this, but getting closer to a more accurate figure is achievable. After all, were the physical elements of an environment may never change, nature and the ever-changing addition of humans would prevent exactness.

Would it not be more beneficial to have at least a more realistic figure to work to? An efficiency percentage to help reduce that 100% unachievable goal.

Lately, we constructed a spreadsheet to assist create this efficiency percentage. This took into consideration the factors that we thought would erode the egress efficiency. We have found it to provide a more realistic timeframe for egress at events. With development, we should gain greater accuracy. It is also allowing us to consider emergency evacuation and provide a truthful evacuation time of a venue/event.

We did consider sharing this spreadsheet. But, a couple of things prevent us from doing it, 1 – what we consider to be influential during egress may differ from you, 2 – we are not the best at building spreadsheets, so it is a work in progress and a learning curve.

It is the idea we share though, the thought of looking at egress with an open mind and not sticking your head in the sand. Also, the provision of evidence in reasoning to reduce the egress efficiency; listing the reasons and factors for the reduction. It is foolish to believe we achieve 100% efficiency in anything we do, so why believe we can egress an event in this timeframe. Have a go yourself. See how you can improve your planning process. 10th January 2018

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