Aerial rigging in trees

[NWCTREES]

Hi All, I am studying a very interesting topic, Aerial rigging in trees. I am aware that many would consider this bad practice, still it happens, often by amateurs and often very unprofessionally. Apart from being an aerial rigger myself I am also an arborist. So it is a topic I want to learn more about, particularly tree assessments. So that if it is going to be done, it can be done safely.

If anyone has any views, opinions, links or are practising in the field, please feel free to share. I'm soon to do a talk on this topic for an assessment task in my diploma level in arboriculture. Any links would be especially valuable.

Many thanks,

Sam

[Jivemaster]

Matter of scale. Would I hang a PAR can from a mature park tree, or would I hang a truss full of movers. I'd also consider bark crush damage, but then I'm into trees too.

[NWCTREES]

Matter of scale. Would I hang a PAR can from a mature park tree, or would I hang a truss full of movers. I'd also consider bark crush damage, but then I'm into trees too.

 

You can eliminate bark crush with suitable burlap and wide webbing. Most big lighting burns too hot to safely rig in trees. Don't want to cook the tree or start a bushfire.

I'm mostly interested in circus rigging, silks, rings, trapeze and the potential shock loads that can be generated, how to eliminate them and most of all how to select suitable trees for the job.

[Seano]

I'm with Jivemaster really - wouldn't necessarily consider it bad practice, but it certainly could be. I've flown the odd catenary wire between trees to get (relatively lightweight) cables up off the deck. Nothing very substantial though. It'd have to be a judgement call really, I don't think I'd consider myself competent to hang more than a fairly trivial load.

 

Most big lighting burns too hot to safely rig in trees. Don't want to cook the tree or start a bushfire.

 

Is a live tree susceptible to heat damage at lower temperatures than, say, a sheet of plywood? Would it need more care than rigging lights around, say, a wooden hut, or in the vicinity of drapes etc?

 

I guess a bushfire is quite a different beast down under than it is in the UK, but here I think a serious risk of fire would quite likely mean the gig couldn't go ahead anyway. Forest fires in the UK often start at ground level, often as not with a discarded cigarette, sometimes a bottle or a bit of glass lying in the sun. Here the punters would most likely be the bigger risk. (Unless you're talking film/tv type work without a live audience present.)

 

I'm not aware of any literature at all around rigging in trees. Are you thinking of publishing something when your studies are done?

 

If you haven't already, it might be worth checking out a few "extreme sports" type forums to see if any slackline enthusiasts have anything to contribute. They'll sometimes rig between trees, and based on the folk I know there does seem to be a fairly big crossover between slackliners, rock climbers and people who work in arboriculture.

[Bryson]

There's a company over here that have done a few shows in the trees of Stanley Park. The guy who runs the company is one of those people who gets an idea, and then will do whatever it takes to learn how to do the thing he wants to do. Might be worth asking about their experiences:

 

http://bocadellupo.com/macro/

[paulears]

I am not remotely an expert in the area of rigging, but I actively read the experts on here when they discuss the dangers, risks and crazy behaviour of people hanging stuff up in the air. Frequently, their concern seems to be that doing X, involves doing Y, and because you do not know how strong something it is, you shouldn't do it, even though it appears safe and substantial.

 

I have just had a 25 year old spruce removed from my front garden because it was huge, the height far above my roof line, and the roots spreading closer and closer. A bit sad, really because it was a nice tree - but the trunk where cut off is about 400mm in diameter, and there's a lot of weight there.

 

As they were loading up the sawn up trunk onto their truck, he casually said "Good idea to get rid of it, look how soft the core has gone - probably not much life left in it before it came down.

 

The centre of the sawn off trunk was much darker and brown coloured, and I could stick a screwdriver into it fairly easily.

 

I'd have assumed my tree was substantial and strong, but trees don't have load figures like truss, and from the outside, my tree looked healthy. How would even a tree expert determine any kind of safe loading figure for a unique item like a tree. I guess you could climb up it and jump up and down and then determine it's ok to hang a couple of par cans, but it's not very scientific is it?

[djw1981]

There must be ways given that Go Ape and people like them happily strap and screw and bolt aerial assault courses etc to many trees across a large area of forrest.

[Jivemaster]

There is no actual rating on a tree or branch, but I suspect that most of us have climbed one sometime! It's a matter of risk assessment, we've all used blu-tac to stick things to the wall but I wouldn't hang a load from it.

[NWCTREES]

The fire issue may not be so great in a live tree but you could overheat the bark and damage the cambium layer beneath. Causing long term scaring. Probably only likely with some of the very hot lights, 5k and over, some of the movers these days burn way too hot. Really would depend on distance, focus and duration.

 

Thanks for the link Bryson, There's a few good tools in the arborist world that can tell you a bit about what's going on inside the trunk of a tree. A Resistograph is a long skinny drill bit that charts resistance when you plunge it in, if you hit soft decayed wood or a cavity, it will let you know.

 

You can also brace a branch at an angle higher up to reduce the stress on a branch and redistribute the load. You can also brace a tree back to the base of another tree if you think there is a risk of pulling a tree over, like in a zip line or flying fox application.

So like Jivemaster says there is no rating on a tree branch and it is all about risk assessment, but you can engineer your way around a lot of things and minimise a lot of those risks.Choosing a strong species with good structure is probably the best start.

And perhaps that's not such a bad idea Seano, I might publish something on the topic one day, but I need to get this assignment done first.

Thanks everyone.

[NWCTREES]

There must be ways given that Go Ape and people like them happily strap and screw and bolt aerial assault courses etc to many trees across a large area of forrest.

 

Have you got any contact details or web address for "Go Ape"? I would love to find out more about what they do.

 

 

 

[Robin D]

http://goape.co.uk/what-is-goape

[marktownend]

My linkThis link isn't for Go Ape but one of their competitors. It shows what happens when it goes wrong! I believe they've since rebuilt it bigger and better.

 

Am I right in saying that there is a certain amount of non-invasive testing that can be done on trees, 'tap-testing' in a similar manner to how composite materials can be tested in F1 cars for instance?

[NWCTREES]

Thanks Marktownend, that's exactly what I was looking for! You rock!

And yes there is a certain amount of non invasive testing that can be done on trees. A friend of mine has a kit that can ultimately Sonic Scope a tree and provide a map of the internal structure, very expensive! Resistograph's are invasive as they tap a small hole into the tree and this can provide an avenue for infection. It generally doesn't as trees are particularly good at compartmentalizing wounds. That's the kind of technology available to an arborist today.

Thanks again, I will use that video in my report.

And thanks Robin D, I see much more clearly where the problem lies.

 

Cheers Sam

[Simon Lewis]

Not quite on topic (mods feel free to split or zap) but on a trip to Go Ape a few years back, we were somewhat bemused to see that each participant's harness safety line was terminated with an alloy carabiner. This clipped onto the zip wire and was dragged behind the user. All of our carabiners had nicely worn grooves in the metal, that you suspected would send a Loler inspector crazy. We queried it and were told it was just fine...

[Seano]

There is a (at least one) professional body covering "high ropes courses", "canopy tours" and the like in the USA. (These are useful generic search terms for the sort of thing that Go Ape does.)

 

I just remembered reading something on their website while following up a rumour I'd heard about a near-miss involving a failed StrandVise connector. (That was slightly mis-used on one of those courses in a way not unlike the way they're often slightly mis-used in our industry.)

 

They're here: http://www.prcainfo.org

 

I'd be surprised if there's not a UK and/or European equivalent. A governing body, trade association, that kind of a thing. Maybe also Aus and/or NZ. (But no time to google now - things to do!)