"I've always made sure that a bridge evolves out of the community, the environment that it's in," says Donald McDonald, the San Francisco-based architect who designed the bridge. As a statement on the importance of the river to the Portland area, Tilikum Crossing was designed to integrate compelling architecture and dynamic river conditions with a thrilling display of light art that now accentuates the Portland skyline, keeping the 55m structure visible and changing throughout the night.
The system design, crafted by Reyes Engineering in Portland, involves a dynamic lighting system that alters the bridge's lighting effects. As environmental data is collected by US Geological Survey equipment, it is translated by specialised software designed by programmer Morgan Barnard. That software triggers a series of commands to an ETC Ion® Remote Processor Unit (RPU) which executes a series of cues programmed specifically for each of those changing conditions.
The late San Francisco artist Anna Valentina Murch and her husband Doug Hollis were commissioned to compose the lighting effects that adorn the bridge structure after dark. Murch's design called for an aesthetic lighting scheme that would change with the behaviours of the Willamette. Murch died prior to completion of the project, but Hollis saw her vision through to the end.
Water temperature determines the base colour, while river speed affects the timing of colour changes and intensity shifts that "move" the light across the bridge. River depth is conveyed by a secondary colour pattern that transitions on the crossing's two towers and array of suspension cables.
Jon Friedemann of HL Stearns Inc., ETC's representative in Portland, originally worked on the project as a control gear and system engineering task. But once Murch discovered the diverse colour offerings of ETC Selador® Desire® LED fixtures, the decision came easily to award ETC the lighting package as well.
"Colour was at the centrepiece of Anna Murch's lighting design," explains Friedemann. "Only the D40 XTI offered a colour palette broad enough to bring her artistic vision to life." Fortunately, ETC's US manufacturing operation offered full compliance with the project's 'Made in America' requirements.
Colour capability, paired with Ion RPU control and a seasoned field service team meant the through line of the Reyes's system design was set - 178 Desire D40 XTIs, a series of DMX opto-isolation repeaters in outdoor enclosures, and over 4.5km of data cable complete the lighting system and integrate it with the collected river data.
Since bridge workers were not allowed to work at night, the D40s were focused by mounting a rifle scope to each fixture, allowing them to be aimed at specific points on the structure. Programming was another hurdle, with logistics and support provided by ETC dealer Hollywood Lights. At night by the riverside, Trevor Burk of Visual Noise Creative in Los Angeles, working alongside ETC technical support engineer Josh Selander, programmed cues on a Gio® console in a rented recreational vehicle - their lodging and control booth for the three consecutive nights of programming.
"It was a small price to pay," says Karl Haas, ETC's architectural national sales manager, "to see a vibrant display of light art, cast on such a breathtaking structure, programmed by one of ETC's most adept technicians . . . while living in a van down by the river."
With much fanfare, Portland held a long-awaited bridge lighting
