Side Bridge Upgrade

[robmonty]

Hi
I am looking for an upgrade solution for the existing side bridges in my theatre. The existing units are about 40 years old, and are U shaped aluminum “swing stage” catwalk like structures,much like window washing platforms, but bigger. These units have fixture hanging positions on the on stage side and a walkway in the middle to provide access for focusing.

They are hung from the grid in the theatre with 2 – one ton CM motors, and can travel from the floor, up and out of the way to about 45 feet. They are about 40 feet long.
Aside from the lighting fixtures hanging on them, they also have some smaller side fill speakers on them, and we occasionally bring them in to the deck and add some masking for the sides of the stage.

Has anyone seen something in a theatre, or touring, that is similar, but has the capacity to attach fall protection?

I will be using an engineer, or buying something that is engineered and approved, but I thought that someone may have a brilliant solution they have seen or are already using.

Thanks
Robert Montgomery
Production Department
Northern Alberta Jubilee Auditorium
Edmonton, Canada

http://www.jubileeauditorium.com/PresenterServices/TheatreSpecs

 

[derekleffew]

... Has anyone seen something in a theatre, or touring, that is similar, but has the capacity to attach fall protection? ...

A Google search for "catwalk truss" returns many possibilities, including http://www.totalstructures.com/products/fixed_catwalk.htm . But it seems unlikely that any would be significantly better than what you already have.

As for fall protection, I would think a retracting vertical fall arrest attached to the grid would be preferable to a horizontal life line, but you really need a consult with a Sapsis or similar.

How are these bridges currently accessed? Wire rope ladder? Fly the bridge to deck and load the electrician on? Transfer from personnel lift to bridge at trim? Other?

 

[robmonty]

A Google search for "catwalk truss" returns many possibilities, including http://www.totalstructures.com/products/fixed_catwalk.htm . But it seems unlikely that any would be significantly better than what you already have.

As for fall protection, I would think a retracting vertical fall arrest attached to the grid would be preferable to a horizontal life line, but you really need a consult with a Sapsis or similar.

How are these bridges currently accessed? Wire rope ladder? Fly the bridge to deck and load the electrician on? Transfer from personnel lift to bridge at trim? Other?

Thanks for the link, which appears to be a more suitable unit than the thomas and arcofab units. We usually load personel on from the fixed side tower next to the bridge, using a Y lanyard. The issues are that the existing unit is not rated for attachement as an anchor, and although it has worked well for 40 years, we have no engineering information on it. It may be easier to start with a new unit, which has documentation.

Using a vertical fall arrest is possible, but a bit of a problem when the focus person is moving along the structure because you run into a horizontal cross structural member of the catwalk structure every few feet. Thats why i was looking for something that could support a horizontal life line, or track, so that you hook up once and away you go. I find the more user friendly we make the safety measures, we get less resistance to using them.

 

[BillConnerFASTC]

Do these need to move or would two fixed catwalks with ladders work? Less expensive and no annula maintenance on chain motors. (They do get torn down and maintained every year I presume and replaced every 5 years or so.) Hard to know without looking at stage and understanding the entire program of uses.

 

[robmonty]

Do these need to move or would two fixed catwalks with ladders work? Less expensive and no annula maintenance on chain motors. (They do get torn down and maintained every year I presume and replaced every 5 years or so.) Hard to know without looking at stage and understanding the entire program of uses.

They definitely need to move up and down. The grid is at 85 feet, but we would need to go from the deck to about 45 up. These are used in the regular position for side light for dance shows, but the opera has used them much higher for some of their shows. We fly them high out of the way when we have touring Broadway shows through that may need wing space, or to fly storage in the wing space.
At 2:42 of this video http://www.jubileeauditorium.com/JubeInteractive/JubeTube you can see the side bridge hanging in the background.

 

[SteveB]

I think that chain motors is probably the wrong application for this and would think that a line-shaft winch system would be a better choice.

But do you need to replace the actual catwalk/bridge unit itself ?, or is it essentially functional just needing appropriate safety systems to allow crew to use ?.

My initial thought though was is the bridge structure really that useful ?. Can you rig more then 2 or 3 units vertically (per wing) and still have focus access ?, or is a flying truss with movable multi-rung lighting ladders that can be re-positioned US/DS more useful, especially as you can rig more units vertically as often desired by dance LD's. You would then a taller man-lift to access, but this is a more common solution for side lighting. Your's is a somewhat odd solution to the side light requirement and the desired height for the opera's - 40 ft ? makes it problematic.

 

[robmonty]

We are considering the truss and ladder idea, but are a bit concerned about the time and crew necessary to focus. Focusing off the lift would work, but requires more time and people, and a lot of the one day shows we do are time compressed enough already.

The existing structure looks a lot like the total structures truss mentioned a few posts up. We have 4 bays, each with 3 pairs of Selecon zooms, one long and one short throw for far side and near side. The ability to walk behind the fixtures and focus, like a normal catwalk is nice, and often we have on person focusing on each side of the stage at the same time.

And you are right, this is really driven more as a safety issue.

 

[SteveB]

Your description clarifies what appears to be a very good system that works for the house.

So what you need to fix is 1) Replace the chain hoist with a dedicated winch. One advantage would be the ability to record targets that allows restoration after movement of the truss to defined positions (deck, low focus, mid focus, hi focus, etc...). Then 2) install a rated safety system for the crew.

So again the question become can you keep the existing truss and simply replace the motors a well as add a safety system.

Sounds like consultant time. Sapsis comes to mind, a well as Jim Neisal at ARUP in NY.


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[BillConnerFASTC]

Sounds like consultant time. Sapsis comes to mind, a well as Jim Neisal at ARUP in NY.


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Please try to keep dealer/contractors like Sapsis separate from design professionals like Jim or I.

It's a lighting bridge and the trickiest parts will be to guide it or not, hoisted or self climbing, and options to counterweight it.

 

[SteveB]

Please try to keep dealer/contractors like Sapsis separate from design professionals like Jim or I.

It's a lighting bridge and the trickiest parts will be to guide it or not, hoisted or self climbing, and options to counterweight it.

You're correct Bill, no slight intended to the fine consultants that grace our forum, I've know Bill S and the firm for so long it was the first thought.