Counterweight vs. Hoist

[AudJ]

Hello CB - long time since my last post, good to be back.

My school district is in the middle of renovating 4 auditoriums. The primary focus is on rigging, sound and lighting. At the 2 elementary buildings, they have opted to forego a counterweight system, dead-hang most of the curtains, and use hoists for electrics and scenery. HS has not begun planning yet, so I do not know details on that one. There is an architect and theater consultant working on the project. I have no experience with pricing on any of the following, so forgive me if my perspective is way off.

The purpose of my inquiry is to see if there is an opinion on asking to change the plan to hoists at the MS. At the Middle School, the design is in the works, but currently looks like 28 counterweight lines on tracks. There is currently no loading bridge, so the design calls for construction of a loading bridge, as well as a 30-40' stair access (don't know what type yet) to the bridge. There is also the possibility that the upper part of the building above the fly rail will need to be reconstructed to accommodate the heavier weight system.

I know to add hoists, there would be a need for a control system, electrical upgrades etc. I also realize a good, safe answer will require careful planning and cooperation with the theater consultant, structural engineer, architect, etc...

In our meetings, concerns have arisen:
- Loss of backstage space to a stair system
- Permanently blocking the only wall that has the potential to add a double-door access to the stage (currently a single 36" door from a 90 degree, 4' corridor entrance to backstage, which does not accommodate our large equipment)
- My eventual successor has issues with height, and will refuse the position if there is a loading bridge...

Questions:
Assuming the beams above the current loft blocks are sufficient (needing to be approved), could hoists negate the need for reconstructing parts of the building or add other support requirements?
Is the cost of a hoist system in any way comparable to a counterweight system, considering all of the extra construction costs each way?

Thanks for any insight!

 

[Malabaristo]

It's really hard to tell without pricing out both options. Hoists are substantially more expensive than manual counterweight linesets, but significant structural changes are also expensive...

For the space I spend most of my time, the math worked out in favor of going 100% motorized. It's pushing 100 years old and was seemingly designed by someone who had seen a couple theatres, but didn't quite understand how they're supposed to fit together. One of the quirks is that the full grid/loft height only extends the width of the playing area of the stage and then drops down over the wings. Adding a loading gallery would have either meant reducing the stage area to allow for shorter battens, or essentially building an addition above one of the wings. The former would have left a uselessly small stage, and the latter had a number of factors that pushed the price into unreasonably high territory.

Some people like to argue that it's good from an educational perspective to have a mix of motorized and manual rigging, and I can kind of agree with that--but only if there's actually staff present who can do that teaching effectively. For the average middle or high school with little to no tech staff, there's a big safety advantage to going motorized that outweighs whatever theoretical training opportunity is lost (in my opinion). Among other things, I love having everything passcode protected with the ability to create and delete accounts for individual student operators on a per-show basis. The various safety advantages to motorized rigging might make it worth choosing even if the cost doesn't completely cancel out.

As far as structural load goes, it depends on what the limitations are. If it's just that the roof system can't handle the total amount of weight you might hang, then motors or manual will have the same issue. The one case where motors can help is if the limitation comes from the lateral loads imposed by a manual system. A motorized system that has a compression tube (or "backbone") handles all the lateral loads internally and only puts vertical loads on the building structure. In some cases this can make a huge difference in where you can add rigging without modifying the structure.

In short: we can't tell you for sure, but we can say that you're right to ask the question and have the design team compare both options before moving forward.

 

[StradivariusBone]

My eventual successor has issues with height, and will refuse the position if there is a loading bridge...

I understand fear of heights, but that seems like a silly hill to die on. I've worked in venues with and without loading bridges and definitely prefer having them. It makes a lot of things much safer and less complicated.

I'm sure he'll see this before long, but @MNicolai will have a lot of advice I reckon.

 

[MNicolai]

What's the existing rigging configuration in the MS?

 

[AudJ]

28 - 4” counterweight line-guided arbors.

 

[AudJ]

I should add, the new system will increase the load of each line set, I don’t remember the exact capacity increase but it is substantial

 

[AudJ]

I understand fear of heights, but that seems like a silly hill to die on. I've worked in venues with and without loading bridges and definitely prefer having them. It makes a lot of things much safer and less complicated.

I'm sure he'll see this before long, but @MNicolai will have a lot of advice I reckon.

Agreed - every job has requirements, and not everyone is qualified or able to take any job based on those requirements. When the job only pays a menial stipend (under 2k per year) it becomes more difficult to fill…

 

[AudJ]

What's the existing rigging configuration in the MS?

Sorry, I botched the reply.

(28) 4” line-guided counterweight arbors

New system adds substantial weight capacity and 6” arbors

Thanks!

 

[MNicolai]

"Substantial" may or may not be a big deal here. It really depends on the original structural design and the margins the original structural engineer designed into that structure.

One of the primary benefits of lineshaft winches or compression tube hoists would be that you're minimizing the additional loading on the structure. With CW, for every pound on the batten, you have a pound on the arbor. And when that weight isn't on the arbors, it's imposing a load on a loading bridge. The CW loads are not only applied vertically but also laterally as the loads transfer through the loft blocks, so the beams typically have to be oversized so they don't twist. In that regard, if a major overhaul of the structure was needed, hoists would give you a more direct replacement -- because with lineshafts or compression tube hoists, you have half the load on the roof compared to CW.

For context, a counterweight set is typically $10-20k (with existing infrastructure, maybe toward the lower end of that -- hard to say), a motorized hoist is $20-30k, and a motorized electric is $50-65k. (Don't look at these "bid" prices -- they are rough orders of magnitude for the purpose of understanding budgetary scale..)

The cost of the loading bridge and spiral stair will be significant. I stay far away from pricing steel but I'd guesstimate more than $100k, less than $200k. If there's a construction manager on the project, they should be able to take concept sketches from the structural engineer to get a ballpark cost estimate on these elements and give you a better sense of how much money you're spending on form instead of function. Honestly -- I'd really question the virtue of adding a loading bridge after the fact. Those need to be sized to handle some serious loads -- it's not just a catwalk supporting foot traffic. Maybe your roof has enough capacity to handle that largely from a high density of hangers, but if you need to support those loads from structural walls of the fly loft, now you're talking large beams that may not be practical to get into the room and erect into place short of peeling the roof open like a sardine can and using a crane.

If the loft blocks and such can be reused and the structure doesn't need (much) reinforcement, it may be worth looking at something like Prodigy EXO. I don't know the ballpark cost on that because I don't run into EXO often but ETC or a dealer could probably give you a ballpark estimate for a rough order of magnitude. That's probably worth exploring and brings the additional safety benefits of motorized controls versus counterweight bricks....but in general, probably still a lot of money to spend on a middle school installation.

Without knowing the space and the caliber of drama/music/etc programs that school supports, it's really hard to second guess another consultant's judgement. I would just say that in my travels on new construction projects, most middle schools wouldn't go anywhere near a counterweight system. It's expensive, dangerous, and at most, they're flying a backdrop or two and motorizing electrics with otherwise mostly dead-hung curtains with a combo of traveler and walkalong tracks. I would hope that the design team is doing their due diligence though and giving a construction manager or relevant subcontractors a few different concepts to cost estimate so that informed decisions can be made.

FWIW -- most architects I work with -- if they knew that they could forgo adding a spiral stair and loading bridge by going to a hoist system -- they would want to get a cost estimate on that before looking at a much more invasive, lengthy installation. Adding $100k to a project if it shaves 2-3 months off a construction schedule could be quite compelling on top of the overall safety and quality-of-life improvements a hoist-centric system offers. And maybe that means you accept fewer sets -- after all, 28 is a lot for a middle school that's probably lacking the production budgets, tooling, and labor to ever really do hefty suspended scenery, and can probably afford to have some dead-hung curtains mixed in there if compromises are needed.

Lot of factors to consider.

 

[AudJ]

"Substantial" may or may not be a big deal here. It really depends on the original structural design and the margins the original structural engineer designed into that structure.

One of the primary benefits of lineshaft winches or compression tube hoists would be that you're minimizing the additional loading on the structure. With CW, for every pound on the batten, you have a pound on the arbor. And when that weight isn't on the arbors, it's imposing a load on a loading bridge. The CW loads are not only applied vertically but also laterally as the loads transfer through the loft blocks, so the beams typically have to be oversized so they don't twist. In that regard, if a major overhaul of the structure was needed, hoists would give you a more direct replacement -- because with lineshafts or compression tube hoists, you have half the load on the roof compared to CW.

For context, a counterweight set is typically $10-20k (with existing infrastructure, maybe toward the lower end of that -- hard to say), a motorized hoist is $20-30k, and a motorized electric is $50-65k. (Don't look at these "bid" prices -- they are rough orders of magnitude for the purpose of understanding budgetary scale..)

The cost of the loading bridge and spiral stair will be significant. I stay far away from pricing steel but I'd guesstimate more than $100k, less than $200k. If there's a construction manager on the project, they should be able to take concept sketches from the structural engineer to get a ballpark cost estimate on these elements and give you a better sense of how much money you're spending on form instead of function. Honestly -- I'd really question the virtue of adding a loading bridge after the fact. Those need to be sized to handle some serious loads -- it's not just a catwalk supporting foot traffic. Maybe your roof has enough capacity to handle that largely from a high density of hangers, but if you need to support those loads from structural walls of the fly loft, now you're talking large beams that may not be practical to get into the room and erect into place short of peeling the roof open like a sardine can and using a crane.

If the loft blocks and such can be reused and the structure doesn't need (much) reinforcement, it may be worth looking at something like Prodigy EXO. I don't know the ballpark cost on that because I don't run into EXO often but ETC or a dealer could probably give you a ballpark estimate for a rough order of magnitude. That's probably worth exploring and brings the additional safety benefits of motorized controls versus counterweight bricks....but in general, probably still a lot of money to spend on a middle school installation.

Without knowing the space and the caliber of drama/music/etc programs that school supports, it's really hard to second guess another consultant's judgement. I would just say that in my travels on new construction projects, most middle schools wouldn't go anywhere near a counterweight system. It's expensive, dangerous, and at most, they're flying a backdrop or two and motorizing electrics with otherwise mostly dead-hung curtains with a combo of traveler and walkalong tracks. I would hope that the design team is doing their due diligence though and giving a construction manager or relevant subcontractors a few different concepts to cost estimate so that informed decisions can be made.

FWIW -- most architects I work with -- if they knew that they could forgo adding a spiral stair and loading bridge by going to a hoist system -- they would want to get a cost estimate on that before looking at a much more invasive, lengthy installation. Adding $100k to a project if it shaves 2-3 months off a construction schedule could be quite compelling on top of the overall safety and quality-of-life improvements a hoist-centric system offers. And maybe that means you accept fewer sets -- after all, 28 is a lot for a middle school that's probably lacking the production budgets, tooling, and labor to ever really do hefty suspended scenery, and can probably afford to have some dead-hung curtains mixed in there if compromises are needed.

Lot of factors to consider.

Thank you for all the info - this makes a lot of sense.

A little history for reference:
The HS was built in the early stages of centralized schools, and as a result was one of the first (and among the oldest performing centers in the region) outside of the one large theater downtown. It became over-used, and its deficiencies became a crutch to bringing in the acts that the community wanted. The MS auditorium was built to correct this, act as a community center of culture and relieve the burden from the HS facility.

In 1955, the Board of Education elected to build a 1,400 seat, 12,000 sq.ft. auditorium with ample space to do pretty much anything we want. The venue has in residence a professional community orchestra, and hosts various dance recitals and other community activities on a regular basis. For the MS musical, our set designer and painter has a resume including Hollywood film scenery. Through the years, many recognizable names have performed in the MS auditorium.

We use all of those counterweight lines, but as lighting options improve, projections become a reality, and modern scenery is becoming increasingly minimal, I can see realistic compromises being viable. As you may guess, the large scale of the auditorium compared to the 700 student enrollment at the MS, has placed a burden of upkeep on the district.

 

[MNicolai]

In that case, I would strongly recommend performing due diligence on a hoist solution. Fewer structural implications and safer/easier to operate. Not having to schlep bricks around also makes it a little faster to do turnarounds if the space is being used as heavily as it sounds like it is. Overall, it would reduce the maintenance and operations burden on the district -- though as with all rigging systems, it should still be inspected by a qualified professional on a regular basis.

If the existing structural capacity is sufficient and no additional lateral kickers/bracing are required, I would consider EXO if the existing loft blocks are in good condition and suitable to reuse with the heightened loads. Otherwise you're looking at compression tube or lineshaft systems to reduce the structural impact. Probably a mix of variable speed for scenery and fixed speed for curtains/electrics.

Still a lot of assumptions here though so this should in no way be taken as criticizing the theater consultant's guidance.

 

[kicknargel]

On a philosophical level I'm pretty uncomfortable with the idea of a fly system in a middle school at all. These are literally cranes operating overhead. I get that this is a mixed-used community space, but the fact that there's only an extremely part-time professional technician indicates to me that the resources aren't there to treat this properly. I think the capital funds for a fly system should come with an operating trust fund to cover a full-time TD.

So, back to reality, I'd say that safety should be the overriding decision factor, and I'd think that points to hoists with lockouts and such. It's too easy for an inexperienced operator to leave a counterweight set unbalanced, and for some curious person to wonder what all the levers and ropes are for and start pulling them. Or for someone to drop a brick from a load rail. These are serious machines for true professionals.