Not arguing, just asking: is this based on any data, or personal opinion?
Although you're certainly less likely to fall out of a lift than off a ladder, the mechanical nature and moving parts introduce new dangers. Like driving off a
stage or coming down on an obstacle that breaks and falls on someone, or any number of things I can imagine. Maybe lifts are safer, but I don't think I'm qualified to say so unequivocally. One of the worst
theatre accidents to anyone I know had to do with a lift that had a tipping feature to get through doorways.
Not so much data - but principle. Although, in the UK the HSE openly admit that falls from ladders are one of the biggest causes of injuries and fatalities in the UK workplace.
A ladder is not, really, a work
platform. You're standing on a rung, and you've nowhere to move quickly, nothing to lean on sideways or backwards of yourself, and little to grab if you are starting to fall. Due to the low weight of a ladder, a fall from a ladder where (by human instinct) you try to grab on to it, can also mean a ladder ends up on top of you after you hit the
ground, furthering your injuries.
I don't disagree that other work platforms can carry their own risks. A
scissor lift or genie lift can indeed by driven over the front of a
stage. Those genies you have to push into position can offer
manual handling injuries. Access towers can be more dangerous to
build at great height than the risk which they reduce - especially when supplied with the bare minimum of parts as hire companies tend to do. But these risks can be mitigated - often easily. For instance, the risk of driving a machine over the
edge could be mitigated by ensuring the
stage is well lit during works, or if this is impractical (IE in a focus) by using a barrier over the D/S
edge. I designed the rigging install and practice for a new
venue about 2 years ago and one of the things I insisted on was that when MEWPs are on the
stage, there is a barrier on the D/S
edge so it cannot be driven over.
Sadly though it is hard to mitigate the risks on a ladder. The very nature of ladders is that they will be fairly unstable and easy to topple, and that the work area you have at the top of them is very small and does not give you any real opportunity to move without risking a fall or toppling the ladder. I saw a very serious
theatre accident where a lampy up a ladder went to move a Source 4
Zoom which had been over-rigged to a fly bar. As he undid the clamp it immediately swung round under the bar and knocked him straight off the ladder - which was a 14 Rung Zarges so he was probably 6m up. It was very serious, it involved paramedics and a spinal board and he was not really alright. Truth be told, had it been a genie or pop up tower... it would have definitely been a brown trousers moment but I'm confident that correct height handrails would have prevented a fall.
I'm not saying risk is eliminated using a work
platform but it is certainly reduced. The only way to eliminate risk in work at height is to eliminate work at height. Hence my
point that the ideal over the
stage is a
catwalk or lighting bridge really, as this is as close to not working at height as you can possibly get, owing to the fact that you're standing on solid
ground with proper handrails. Adding work restraint
PPE so that you cannot possibly get outside the
foot print of the
catwalk adds further mitigation. The only reason I did not include bridges in the
venue I did, was because it is multi use and the
stage can be in so many different places that it would be impractical to use fixed bridges. Instead I went with a
tension wire grid which is another excellent mitigation for work at height, the risk of falling is none, without the catastrophic failure of the
grid.
I was also looking at the Little Giant Cage ladder recently, working height up to ~19' with a
safety cage at the top of the ladder. Other than the high theft risk (they grow legs pretty quickly on construction sites), these seem like a great option for safer use of ladders.
It's a nice idea but sadly they only go up to a 14'
platform height which is 19' max working height which is about 5.5m. Still not high enough in many circumstances. A
Tallescope is not a massively different concept and goes much higher. Pop up scaff towers are, in my opinion, an excellent idea. But mechanical access is still, IMHO, the best. As long as it is used in a safe environment by a competent person, the floor space, the handrails, and the lack of fatigue through not having to climb it, make it the safest option overall.