Aida: Pressure Plate Runway
In a particular scene for our production of Aida, there was to be a fashion runway that models would strut on. In discussing lighting, we decided to line the edge of the runway with lights. I pitched the idea of controlling these lights with pressure plates. The plates would be along the runway every two feet such that as the actresses walked and stepped on plates, they would be illuminated from the sides by the lights at that point on the runway. Our director's curiosity was piqued, so I got to work.
Creating this effect certainly took more than I thought it would. It was not easy to create a pressure plate that worked reliably and consistently, wherever it was stepped on. My first design, which was totally horrendous in retrospect, involved making the plates out of thin luan sheets, which would bow down when stepped on, creating electrical contact between the two plates. The design ended up working somewhatish, but it wasn't very solid or reliable. It would make terrible crunching sounds when stepped on, and plates would occasionally be snapped off completely while being moved against other set pieces, exposing potentially dangerous conductive plates underneath.
I was totally not comfortable putting that on stage. It was risky crunch of time, but just a week before the show opened, I decided that I wanted to totally scrap the design and redo it entirely. I ordered some hefty springs from McMaster-Carr, one of the best places on the internet, with rush delivery. Instead of flimsy luan, I cut the plates out of plywood and attached hinges on the outside edge. The springs went on the opposite edge, underneath the plate. This design was solid and delivered consistent results. I was happy about it, and it worked well in performance. The only improvement I could have done might have been to use shorter springs, for slightly less travel distance, and to possibly use squishy foam underneath the plates to dampen the sound.
The runway itself consisted of four separate pieces, which when separated into two pairs of pieces, doubled for use as a dock in two scenes on the water.
Because the runway was physically split down the middle, an electrical connection had to be made between the two sides so that there could be an electrical communication, such that stepping on one pressure plate would activate not only the light next to that plate, but also the corresponding light on the other side. The circuit diagram above illustrates how this connection worked. The connection was made simply with an electrical outlet and plug, using the four contacts in the pair of plugs for each of the four plates.
