In the Information Age, the least high-tech items tend to be the most overlooked. The high-flying but low-tech catwalk is chief among them. Both the balm and the bane of riggers worldwide, the catwalk is as cumbersome and expensive as it is necessary, which explains why they are often routed worse than flying commercial out of a small town in northern Wyoming. Particularly at a time when the curved polygonal theatre seating design has become more and more common, those who look up during intermission are seeing more and more burned-out lamps in places where the catwalk simply doesn't go.
Catwalk Geometry
The owner of a Midwest sound and lighting systems design and integration company may have come up with a game-changer in the catwalk department, however. While working on the planning stages of the Faith Family Church in Canton, Ohio, John Westra, who owns Audio Design Specialists, a systems integrator, and Venue Technologies, an acoustical treatment fabricator, both based in Madison, Wis., was ready to install steel acoustical clouds developed by Venue Technologies as the church's ceiling. He noted how the LD's right-angle-heavy catwalk design seemed at geometric odds with the fan-shaped polygonal seating design. It occurred to him that a catwalk could follow the geometry of the floor design more precisely, and also serve as the suspension system for the facility's sound gear, lighting components and more.
"Virtually all media-wise churches today employ fan-shaped seating," Westra explains. "In most cases, the ceiling geometry above will mimic the seating layout below, being either curved or polygonal, approximating the curve, and therein lies the problem with linear catwalks. Also, catwalks should not be limited to theatrical lighting. If properly sized, shaped, and positioned, they can also support house lighting, work lighting, loudspeaker systems, auxiliary video projectors, fire sprinkler mains, and, most importantly, the ceiling itself."
A Modular Design
Westra proceeded to design a catwalk based on a modular design. Each nominally 8-to-10 foot-long by 8-foot-high unit offers both a pathway and a structure to which customized arms and outrigger pipes can be attached to rig systems components. Each modular section can have precisely-mitered angles at the ends to connect them, creating any geometry desired at any length. Strength is derived from the design of the frame. The top frame assembly provides a mounting plane for cable trays, connector strips and inter-catwalk beams for cloud suspension. The main supports are factory welded; other components bolt together for ease in shipment, simplified onsite assembly and reduced cost.
After extensive 3D CAD modeling, Westra's crew put together a pilot version of one run for the church in their shop, timing the process of assembling and flying the rig, which would be critical to the bidding process. At an estimated $438 per foot, installed, the custom-fabricated Venue Technologies catwalk would certainly be more expensive than a typical one built by a local rigging company. However, once the cost of other rigging for speaker bins, lights and other systems nodes was taken into account, the cost quickly falls closer into line with that of the conventional catwalk. Then, there are less easily-quantifiable but just as important aspects that have to be calculated.
"It's common in large auditoria to see burned out house lights," says Westra. "They're hard to reach, and bringing in a lift often results in damage to doors, carpet and seating, not to mention the rental costs. So the lift option only gets used when enough fixtures have burned out to force lamp replacement." Hanging lighting from the catwalk encourages lamp and element replacement, as it does for any other system element that needs attention.
Concentric Polygons
Based on the pilot testing – including an industrial engineering study that found that the actual installation time turned out to be exactly what was predicted – Westra received a green light from the church. The overall configuration consisted of one-third mile of catwalks, five as concentric polygons, over the seating area, three parallel runs with cross members over the stage, and a series of access units running polygon to polygon, hung an average of 32 feet above the seating area.
Rigging the system illustrates some of its innovations: all welds made at the factory, in a manner so that subassemblies simply bolt together in position. The traditional method is to fabricate relatively large sections on the ground and then raise them into position. The modular Venue Technologies catwalk is assembled at elevation. End frames are suspended first, managed by two men in a reasonable-sized lift. The top frames are next, followed by the bottom frames, then the decks, and, finally, the rail pipes, outboard arms and outboard pipes. The parts are self aligning, ensuring that the desired geometry and precision are obtained.
From that structural network of catwalks, 40 large loudspeaker bins were hung in concentric arcs, with arcs two, three, and four time-delayed relative to arc one. A series of outboard arms and pipes that could be positioned as required, both vertically and in offset distance from the catwalks themselves, support the theatrical lighting fixtures, house lighting fixtures, work light fixtures, loudspeaker systems and an auxiliary center screen video projector. Compared to the catwalk/truss combination, individual suspension of these loudspeaker systems would have been extremely costly. Also important: The ceiling consists of a radial pattern of large multifaceted steel clouds, and individual support of the clouds would have been extremely difficult. But using the Venue catwalk system, a radial pattern of steel square-section tubular beams could be employed, spanning between the upper frames of the concentric catwalks. The clouds were suspended from these with pre-manufactured lanyards. The total supported load is approximately 290,000 pounds.
The Canton, Ohio church project was finished last March. Since then, three more projects are under consideration or in planning stages. Westra says the catwalk design is applicable to any production venue, and with its high-load and seismic ratings, it can be deployed pretty much anywhere. It brings the lowly but loved catwalk into the digital era, along with all the technical bling you can string from it.
