Sorry, I'm late in this discussion, with a subject, suddenly made more interesting through the comment #27, from
Goofyernmost ... ;-) ... I have been a silent reader only, on these forums, until now.
That being mentioned ... I can add something to that specific comment.
I'm in the concept and design buisiness, having a professional insight in capacity planning.
Point one : (quoted)
Building capacity and park capacity is determined by fire, rescue and emergency agencies and it is a formula that tries to determine how long it would take to evacuate a building, park or whatever safely.
Actually, first correction : with building capacity YES, with park capacity: not really.
A possible calamity is:
located. This is always ONE building at a time. It does not concur with the whole park.
Does this mean it is never applied to outdoors areas? Yes, it does, but the circunstances of handling this are way different, and do, in most cases, not apply to complete parks, but more specifically to dense open air show areas (seated or standing). Then again, we can point out thar the possible calimity is
located.
Confusing for most people :
Most theme park fans will be familiar with the many videos shot at 'evacuation' (attraction broke down), and see something that has no relation to potential calamity evacuation. Evacuation of a ride at some break down, has everything to do with customer relations (still having happy, returning custumers at the back door = the goal), and has nothing at all to do with fire rescue, or similar.
In most attractions, the actual total occupation from the factor "FILL" = the maximum number of people that can be inside a showbuilding, is determined by the other factor "THRC" (theoretical hourly ride capacity = the technical maximum that will never be trespassed) together with the runtime quotes in all of the composing parts of that attraction. (OK, yes, there are formulas fot that). Fact now is, that "FILL" in an attraction always is small compared to the size of the showbuilding. EXCEPT for theater style attractions.
Planning emergency exits (and safe exit routes) is quite easy. Where it's really problematic, is in situations of uncontrolled party assembly (café-bar-clubs-dancings, shops... etc etc and yes, FEC's !!...) because those are situations where people constantly, and very much uncontrolled thus, walk (rush) in and out.
In the attraction environment, the FILL factor is determined and controlled. It set's this theme park leisure industry apart from the general leisure scene in city centers.
In the open air, it's FESTIVALS and similar events, that cause the big problems. A panic, can mean people are killed because they crush each other to suffocation. There, crowd control becomes the biggest issue. In theme parks, the issue is not worse then just crowd management.
And so... definately :
NO, complete theme parks are NEVER evacuated ! Exactly THAT would be irresponsible dangerous to do !
To the contrary. The only general calamity that came over a very large theme park, ever in history, was the earthquake / tsunami, with Tokyo DL resort. The rule then, is the exact opposite of evacuation : it was PROHIBITED to leave the park !! (At full calamity control logic.)
At the follow up point in comment #27 (quoted)
.... more attractions to help balance out the crowd, that is another different scale. All that does is spread the crowd out more evenly, but isn't necessarily considered when evacuation is needed. ...
So, again, this global park evacuation is
not done ! In terms of fire rescue policies,
outside = SAFE. Dozens of "rescue assembly points" are allocated in the planning, throughout theme parks (inside the park, and at the backlots), just to make shure people can be "counted".
"...help balance out the crowd" , is what is done in 'crowd management'. The actual configuration of the park should help this in the first place, but the peoples behaviour is not calculable and very often operational tricks come in (on time or late ... lol ) to keep people moving. Although, only on peak attendance days !
When the parks walkways would be so crowded that they start to resemble a rock festival situation, however, then the park closes its front gates (or should) ... it happened a few times at WDW Magic Kingdom. I do not know of any other instance of such a front gate lock-up, anywhere on earth.
Cheers.