Truss Climbing, For lighting focus, etc. Options

[Jivemaster]

As far as I was aware, the transition from basket to something else at height was considered riskier than acceptable because of the possibility that the extended boom and the position of the other structure could shift on the transition of weight. The boom swaying away from the truss or platform, leaving the possibility of falling between the two, at height, needing a suitable harness point and rescue plan. Even if you are going to a structural architectural landing point an elevated work platform can sway.

[Seano]

On one hand you want the trusses to be safetied before anyone climbs them, but then how do you rescue a person if they fall from the truss?

Personally, all other things being equal, I prefer a truss not to have secondary suspensions in place when people are working on it. Being in a position to lower the truss under power immediately is a vastly superior rescue plan in most cases for most people than any kind of rope shenanigans.

The trussess need o be saftied/scondaried up as part of our general rig policy (a point failing in load in is as dagerous as one falling mid show after all) -rescue at the momnet involves employing a second rescue technican to be able to abseil down and perform a rescue in the event of a fall.

A point failing with a "safety" would, in the majority of cases, scarcely be any less dangerous than one failing without. This is because many secondary suspensions as they are applied are pretty much just there for show. And in my experience this tends to be the case more often in the venues that are most dogmatic about "safeties" and stick to a rigid policy rather than assessing things case by case.
Things might actually be made a little bit safer overall if your policy towards secondary suspensions was slightly more pragmatic.

Its also worth noting that there are motors on the market now that clearly don't require a secondary suspension, Loadguard for example. They have several advantages, not least of which is that they eliminate what is usually a bit of work at height - applying and removing the 'safeties' themselves.

Rescue by abseil in a genuine emergency is probably a lot more difficult, and hazardous than people generally realise. If you really want to do it right, it may also be expensive. People who don't use roped techniques regularly can't realistically be expected to undertake a rescue quickly, efficiently and safely months or years after a short course if they haven't had regular training and practice since.

Regarding the 'heirarchy of controls' already mentioned above - your first option is to avoid work at height. If its at all practical it would be better to lower the truss for maintenance than to go up to it. Use of 'high integrity' hoists, or removing secondary suspensions from accessible rigging points above to facilitate this would be preferable from that 'heirarchy' point of view than accessing the truss in situ.

Next - if its reasonably practical for you to use an access platform rather than climbing, you have a clear duty to do so even if it does cost a bit more. But is it always going to be practical? You mentioned a steeldeck stage - obviously you wouldn't be able to drive a self propelled MEWP on it, so will you have enough outreach to get over to the truss in question from the nearest position you can drive the machine into? You may find you'd need a larger machine to do that than you'd think from looking at the height of trusses alone.

I'm more concerned that there isn't a way that truss climbing can take place in line with manufacturers guidence...

You're confusing slightly different things here, I think. On the one hand you have climbing on the truss, and on the other you have the use of the truss itself as a fall-arrest anchor. Two different issues.

The position WorkCover in Australia takes is that when you transfer your weight to a suspended structure from an EWP, you have no guarantee that it can take your weight.
The risk they see, and I think is fairly reasonable, is that when you step from an EWP onto a truss, that could be a cause for it to collapse.
If you use a rope ladder to climb up to the truss, that failure to support your weight happens when you are a couple of feet from the deck.

Interesting theory, though there are a few holes in it I reckon. For one thing, if the structure is in risk of collapse because of the dynamic weight of one human being something has already gone disastrously wrong! Safety factors have been so seriously compromised and the SWL so far exceeded that its probably only a matter of time before it falls down anyway. Fortunately, the nature of aluminium trusses is such that it'd look pretty terrifying well before that stage. I don't know if you've ever seen a truss broken, but they deflect a *long* way before failure. A truss close to that point doesn't look like anything a sane person would choose to step out onto.

Secondly, when stepping onto a rope ladder, you're directly beneath the structure pulling down on it with 100-125% (ish) of your bodyweight. Scarcely a safer place to be if it should happen to fall out of the sky than standing on top of it.

Finally, truss ladders are generally rigged at the end of a truss, or in any case close to a point of suspension. If a truss was going to fail catastrophically under the weight of one tubby lampy, it would be much more likely to happen when the lampy was at mid-span. (ie: has already climbed the ladder and traversed some way along the truss)

Oh, and yet another thing (sorry about the length of all this blah blah.. )
Rescue (again). Rescuing a person still in a picker basket is easy peasy. Climbing a truss ladder is an activity that should be covered by a rescue plan, and that could be much more tricky.

The boom swaying away from the truss or platform, leaving the possibility of falling between the two, at height, needing a suitable harness point and rescue plan. Even if you are going to a structural architectural landing point an elevated work platform can sway.

True of course. Though in this case the discussion is mostly about making the transition from the basket to a structure that requires a system of fall arrest anyway. So the user should already be wearing a suitable harness, and I'd suggest the sequence of events would be: disconnect restraint lanyard from basket then connect to fall-arrest system then exit basket. (Taking care that at no time is there the possibility of becoming trapped should the basket move during the transition - eg by routing a fall-arrest lanyard through handrails.)

Yes, of course the possibility of the basket moving under the weight of a person leaving/entering the basket is something to be aware of. 'Sway', generally is more of an issue with a sideways force - that mostly seems to happen in my experience when the basket is not quite in the right place and the operator is stepping across a gap etc. The most common cause of that imo, is when the operator is too impatient to fiddle about for a wee while getting the basket in the right place.

Edited to add:
Of course climbing out of a picker basket would usually be considered 'riskier than acceptable' under the hierarchy of controls in any case. That's because its work at height protected by a fall-arrest system, which is lower down the list than working from an access platform. (ie: the preferred option of remaining in the basket and putting the basket where you need to be to do the job)

This post has been edited by Seano: 5 Aug 2010, 10:07 AM

[Chris Adam]

in the rock and roll side of the industry truss access is by caving ladder and fall arrest block. very standard bits of kit but would need a day or so familiarisation so you get the hang of climbing the ladder.
52cm supertruss (I cant speak for PROLYTE) is perfectly suitable for climbing about on. Riggers and lampies do it every day on tours etc. you would need to either have a horizontal safety line (anchored to independent points not to the truss) or use a Y lanyard and the double clipping method of truss access.

If you were to contact any rigging company they would be able to advise you of the best method and arrange for a training day for your techs.

TM

I'd be interested to know what your standard harness anchor system is for this. This isn't a trick question, I am genuinely interested as I'm looking to make some amendments to the system I use just now.
I also climb with a truss ladder and fall arrestor at the end of the truss. I have a 5 ton SWL line when I'm up there and two lanyards for moving around, but there doesn't ever seem to be a "best Place" for that to be anchored, as I'm moving around a large box, so there's four seperate lines.
Please PM me if you'd rather not open yourself up to scrutiny.

cheers

[trussmonkey]

Chris,

Personal PPE would be

full body harness
helmet
double engery absorbing Y lanyard
petzl grillon (for work positioning)
and a couple of Petzl MGO carabiners/hooks

you can look up the appropriate EN numbers yourself.

Normally a rigging supplier would install a horizontal safety line (spanset make the most typically seen ones) between either the two ends of the truss or the two end hoists. Both of these are not ideal solutions for many reasons. Truss manufacturers state that the truss is not designed for this purpose and can not with stand the loads of a person falling onto a horizontal line anchored at the ends of the truss (Total Fabs T2 truss is the only fall arrest truss out there but that requires special training to use and as such doesn't feature in most rigging companies general stock). Putting the horizontal line between the end hoists will have a similar effect as on the truss as it will induce a side loading on the point. It will also tow the hoist out of plumb when the horizontal line is tensioned. We (my current employers) don't like this and where possible we specify they the double clipping method of truss walking should be used. It is more time consuming but inherently safer if all goes wrong.

Fall arrest blocks are also not allowed to be rigged on the truss in the truss manufacturers paper work for the same reasons as horizontal lines. I would say the 90% of all shows I see coming through the O2 and other venues have rigged as separate points direct to the roof.


There are euro/british standards to which the safety lines have to comply with as well as the rating of the anchors.

TM

[CaptainMeat]

A point failing with a "safety" would, in the majority of cases, scarcely be any less dangerous than one failing without. This is because many secondary suspensions as they are applied are pretty much just there for show. And in my experience this tends to be the case more often in the venues that are most dogmatic about "safeties" and stick to a rigid policy rather than assessing things case by case.
Things might actually be made a little bit safer overall if your policy towards secondary suspensions was slightly more pragmatic.

Hold on a second... this is going a little bit off topic, but as it's been brought up

Secondaries that cannot take a full weight of the load or cause excessive movement are dagerous, and as such if anyone practices this, not only are they a massive idiot, but an arrogant ###### as well.

The policy on safties is there for a very good reason - we have a different company rigging EVERY day. House trussess are set up in a way that is exactly as we have in the book so pople can't argue without evidence to back them selves up. This policy exists becoause of the range of kit we've had brought in over the years - we (as the venue) don't know anything about its history before it comes in, and so, with out chasing for documnetation for every day, we can instantly see for each rig that goes up has a backup system should a motor point fail at any point in the suspention - unlikly, but still possible.

As I've said further up this thread, we've gone for a picker with long boom option - safe, efficent and not hampered by any other system.

[Chris Adam]

Chris,

Personal PPE would be ...

Truss Monkey,

Thanks for being so detailed. This is the exact system we have in place just now, I was just considering alternatives. The main thing I don't like about this system is that when I am walking on top of the truss, the harness point is at my feet, which means I have to fall my own height first, before I even start falling to the harness lanyard length. I trust my equipment, but still don't fancy it!!
Thankfully my rigs aren't massive, so can still walk along the side of the truss without taking too long. yet!!

Thanks again though.

Reason for edit: Quote snipped

[dynamo_ozz]

Greater fall factor, greater risk of serious injury. I understand your concern. You're so right.

Reason for edit: Quote snipped

[trussmonkey]

chris,

dynamo is right the greater the fall factor the greater the injury. most rock and roll horizontal safety lines are rigged under the hoist in between the truss wrap and motor hook. if you want the horiz line higher you can add in a short steel (stinger) to raise it up but you will loose trim height. truss walking is done along one of the sides of the truss with your body's centre of gravity over the top of the truss. it takes a little practise but it soon becomes second nature.
this way the attachment point of the energy absorbing lanyard is above you (ish) and there for the fall factor has been reduced.

there are other issues i.e. rescue but that is another topic.

TM