Mobile Stage Safety, In Theory and In Practice


Mobile stage merchants will be the first (and sometimes the second, and third) to tell you their stages offer significant safety benefits over traditional cable-and-ballast structures. But mobile stage safety isn’t in the stages’ nature so much as it is the product of the relationship between safety theory and safety best practices. Two of the directors of Stageline, one of the most recognizable names in mobile staging, spoke to Event Safety Insights about the relationship between theory and practice in how their company approaches the life and death issue of stage safety.

On the subject of the theory of safety, ESI spoke with Stageline’s Engineering Director Jonathan Doucet, who has been with the company for more than a decade.

EVENT SAFETY INSIGHTS: What are the guiding principles of safety for mobile staging?
Jonathan Doucet: The basic premise is that we include safety in the design from the very first starting point with any new design and we try to minimize the amount of work that will depend on humans, who are unpredictable. Therefore, all of our designs use sequential deployment, which means that if you want to go from A to C, you have to go through B—you can’t go directly to C by accident. We try to do that with everything we design.

ESI: You don’t set up your stages the way that anchor-ballast stages are set up.
JD: No. We don’t use cables that go directly to the ground or ballasts that are required on all standard units, because they’re not safe enough. Instead of ballast, we rely on the self-weight of the equipment since it’s always the same and it can’t be removed, so that cuts out the possibility of having an error in connection with a critical element for any safe operation of a stage: wind resistance.

ESI: What’s the advantage to self-weight over ballast?
JD: With anchors and ballasts, there are many points where mistakes can occur and things can go wrong: cables are like a chain, where you’re always subject to the weakest link. The connection between your cables and your ballasts can be weak. There’s friction between the ballast and the ground to keep in mind. When you use guy-cables, you have a lot of things to verify. Any one of those things can go wrong. Self-weight is easier: it makes it very hard to forget anything. This goes back to our first point to minimize the human factor in the equation of stage construction. The more we minimize their involvement and streamline the stage to make their job easier, the more we reduce potential for human error.

ESI: How do you go about designing a stage that minimizes human involvement?
JD: You design with the worst-case scenario in mind, for risk management. Think of what it’s possible to do, even if it isn’t likely. That could be human error, a huge wind, a storm—just think of the worst conditions operating the stage.

ESI: When you’ve figured out what your potential risks may be, how do you design a stage that can be ready for them all?
JD: The main way to do that is by calculating safety factors. This is where our approach doesn’t follow the minimum standards, it exceeds it. A safety factor of 1.6 is considered an acceptable minimum, but if you look at the possibility of dynamic loads and the action of rigging—those alone could have an impact of between 1.5 to 1.7 on any structure. So for us, we make all our safety factor a ratio of 2/1 for all load cases we consider, because it’s simply safer.

ESI: That’s a significant increase on the published norm.
JD: From our point of view, norms and standards are existent to state the minimal requirements, the entry points, but nothing in these codes prevents you from doing better. Instead, it’s worth asking, ‘Even if the norms say this is acceptable, is this the safest solution we could provide?’ We don’t gamble with safety, so we adapt safety factors to the realities these stages face, rather than designing them to a minimum imposed criterion. From there we can ask ‘what’s the real target we need to hit, rather than the official one?’ The ANSI E1.21 – 2013 is the guideline we’re supposed to follow, but we pride ourselves with doing more than that.

ESI: How so?
JD: For wind-resistance, they list 40mph with all windwalls. But 60mph wind is quite common and we see it quite often on various event sites across North America, so less than 60mph is not enough for us. If you remove windwalls, they list wind resistance at 67mph, but for us, we go with 90mph. We’ve seen over and over again at events that winds from 60 to 80mph really are possible. You have to be safer than the norm if the norm doesn’t seem safe enough.

ESI: On the technical level, how do you build safety into the products?
JD: You need to always keep redundant systems in place for every element that could involve a catastrophic scenario, like wind resistance for example. If a system fails in resisting strong winds for example, there has to be another system in place to resist it. One thing that we do is that we remove the hydraulics from the calculation, meaning no matter what happens within our calculations, if everything else fails, we’ll have the hydraulics to fall back on to keep the moveable parts up, mechanically pinned and secured. This provides 100% redundancy on all movable parts. Meanwhile, within the hydraulics there’s also redundancy: we have block valves on every hydraulic component, so if a hydraulic line is cut and all pressure disappears, everything locks up. That way we’ve got layers of safety redundancy everywhere. And when I say we want to have a safety factor of 2.0 everywhere, we don’t just rely on our calculations; we physically test every unit at double its capacity, in real life. The standard safety minimums ask for theoretical calculations, but we don’t believe that’s enough. So we design with higher criteria, and we test under real circumstances.

ESI: If you’re designing to a higher standard than the minimum, does that mean the final say on safety is really up to your engineering team?
JD: Actually we have our designs double-checked by external engineering teams to make sure we didn’t build in any human error ourselves. That’s not something imposed in the standards—no one’s forced to have a third-party looking over their shoulders, but we feel that our industry as a whole should be double-checked. So yes, our engineers have stamped all our designs to say the calculations are correct, but we don’t feel comfortable until that’s been checked by an external source.

Pierre-Luc Rompré, Stageline’s director of Sales and Rentals, is a specialist maintaining a high level of safety in the field when deploying mobile stages on site. He’s also an engineer and has been with the company for ten years leading their operations.

ESI: We’ve heard the theory, how do you put all that into practice?
Pierre-Luc Rompré: The first step is clearly defining the roles and responsibility for everyone involved in the equation of setting up, tearing down, and overseeing the stage. In our contracts and documents, we lay out clearly who’s responsible for what down to the last person, and we determine in advance how we’ll communicate, how we’ll verify everyone else’s work, and crucial things like who’s responsible if the weather is bad for deciding whether to put in action our weather action plans.

ESI: Once you have a client who’s planning to rent a stage, what steps do you take with them to make sure their vision for the stage can be realized safely?
PLR: We start by verifying all rigging plans. Because our stages consist of machines that are pre-engineered, they have capacities detailed in the rigging plans. For every show we do on our stages, we ask to see what the producers intend to fly in the roof. We double-check their plan and compare with the capacity allowed on the stage they’re renting to make sure they’re not overloading the rigging, or rigging in a spot they’re not supposed to be rigging. Then we communicate their approved rigging plan with both the Production and the on-site technical crew so we’re all on the same page.

ESI: As you approach the actual show in the field, how does this information come into play?
PLR: It’s important to communicate all information to the people in the field executing the work. We do that here before the show—verify the rigging, yes, but also the logistical plan, the stage routing, the last event report for the previous show. Things like that. How the event is actually going to unfold in the field. Often the technicians who are going to execute the work are not on the pre-production calls, so we need to transfer that info clearly to them. It’s important not only to do due diligence ahead of time, but to convey the information to those people in the field to make certain they’re equipped to verify what’s done on site. This is connected back to that distinction of role and responsibility: we make clear from the beginning that they have the authority to act on behalf of Stageline to say to the people doing the rigging, the promoter, or the technical director: ‘No, this is not correct, and this was not approved in that way. You cannot make these changes.’

ESI: From a technical perspective, what kind of role do Stageline trained employees play on site at an event?
PLR: As much as our machines are designed to take human error out of the equation, they still need to be operated by certified technicians. Every tech on site responsible for operations, deployment, and installation—as well as supervision and monitoring of the installation during the event—they all need to have gone through proper training and have the proper background knowledge and skills to make the right decisions at the right time. That’s why we have built over time a training program for every model that we sell and rent, to make sure the techs are safely qualified to face the challenges coming their way out in the field.

ESI: That presumes that they’re engaging with a structure and machine that are working exactly as they should be. Who’s responsible for that? What role do stage renters play in keeping their equipment up to date?
PLR: All equipment that’s in use has to go through an annual inspection to make certain all the structural elements in place are in good shape to face what’s coming their way. Either through Stageline or a neutral third-party engineering firm, you need someone that can actually put their eyes on the structure and the machine and formally attest that it’s safe to work with. Attached to that is the formal maintenance of all the equipment. If the equipment is not maintained—it’s just like your car. If you don’t ever have your brakes looked at, then one day you’re going to come to a red light and you’re not going to be able to stop. It’s the same with our equipment. These are machines that require maintenance to stay on top of their safety record.

ESI: These are a lot of demands. Do people find that can be a strain on their budgets?
PLR: Well, the question is really, ‘Is there a way to do this cheaply?’ We were having conversations about that at the latest Event Safety Summit and we are firm believers that the answer to that questions is no. There’s only one way to do this, and that’s the right way. It takes time, qualified personnel, resources and equipment of high quality. In the world of RFPs where people are trying to find the cheapest price possible, we share the opinion that desire for low prices is one of the things that triggers safety incidents. If you’re going in cheap, then chances are strong that some corners will be or have been cut somewhere: was it on maintenance? Structural inspection? Training? Planning? You can’t deliver safe and high-quality and have cheap at the same time.

Jacob Worek