Light-art bridges the Willamette River

Date Posted: 10/28/2015

Tilikum Crossing, Bridge of the people (Photo credit - Photo courtesy of TriMet)

Spanning the Willamette River in Portland, you'll find a confluence of nature, light, art, engineering, and architecture. Tilikum Crossing, Bridge of the People, is the first new bridge in the Portland area in 40 years. Accessible only by pedestrians, cyclists, and mass transit, it's an eye-catching spectacle both day and night, designed and lit to emphasize the importance of the river to the city and its inhabitants.

"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, dynamic river conditions, and a thrilling display of light art that now accentuates the Portland skyline, keeping the 180 foot tall structure visible and changing throughout the night.

Tilikum Crossing bathed in orange

The system design, crafted by Reyes Engineering in Portland, involves a dynamic lighting system that alters the bridge's lighting effects based on the Willamette's speed, depth, and water temperature. As environmental data is collected by U.S. Geological Survey equipment, it is translated by specialized software designed by programmer Morgan Barnard. That software triggers a series of commands to an ETC Ion® Remote Processor Unit (RPU) which then 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 behaviors of the Willamette. Murch died prior to completion of the project, but Hollis saw her vision through to the end.

D40XTI array on bridge structure

The result is something organic, unpredictable. Throughout the night, nature itself plays a role in the look of color and light cast on the cable-stayed bridge; as the river conditions change, so does the lighting design. Water temperature determines the base color; river speed affects the timing of color changes and intensity shifts that "move" the light across the bridge. River depth is conveyed by a secondary color 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 pursued the project for ETC's control gear and system engineering. But once Murch discovered the diverse color offerings of ETC Selador® Desire® luminaires, the decision came easily to award ETC the lighting package as well.

Tilikum Crossing, cool wash reflection

"Color was at the centerpiece of Anna Murch's lighting design," explains Friedemann. "Only the D40 XTI offered a color 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.

Unmatched color capability, paired with Ion RPU control, ETC's proficient systems engineering and a seasoned field service team, 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 15,000 feet of data cable complete the lighting system and integrate it with the collected river data.

Focus proved difficult, as bridge workers were not authorized to work at night. So the D40s were focused in full daylight by mounting a rifle scope to each fixture to aim the lights 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 and 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.

Tilikum Crossing, between the spires Photo credit - (Photo courtesy of TriMet)

"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 ceremony on September 10th , and Tilikum Crossing, Bridge of the People, officially opened to pedestrians, cyclists, and mass transit on September 12th , 2015.