By now you’ve seen how Tilikum Crossing, Bridge of the People, lights up the night — but how exactly do those lights work?
There are 178 LED lights aesthetically placed on 40 bridge cables, the four transmission towers above and below the deck, and on the Sonic Dish artwork along the Eastside Esplanade and future Willamette Greenway at the ends of the bridge.
Monitors from the U.S. Geological Survey and the National Oceanic and Atmospheric Administration, located in the water near the Morrison Bridge, collect data from the Willamette River. A program developed by digital artist Morgan Barnard translates the data into a colorful and aesthetic display.
(Video: December 2014 Testing)
The temperature of the river controls the color of the lights. Warmer river conditions will display warmer colors, like orange and yellow, while cooler temperatures will display cool colors, like green and blue.
Notice how the lights seem to dance across Tilikum Crossing? That’s controlled by the tide. When the tide is coming in, the lights move towards the center of the bridge. As the tide goes out, the lights move towards the ends of the bridge. Additionally, the tide levels affect the speed of the lights. When the tide is higher or lower, the lights move faster. At midpoint, the lights move slowly.
The speed of the river controls how quickly the colors change. If the river is moving fast, the colors will appear to move and cycle through quicker.
The river’s height affects the contrast in the lights. The higher the river, the more contrasted the colors appear, which affects the pattern and movement of the lights. This change varies with the season, so in the summer (when the river levels are pretty static) the bridge color will appear even and bright. In the spring, when the water tends to move more, the bridge colors will appear more fluid.
While a lot of scientific data is gathered to create this aesthetic light display, the bridge lights aren’t meant to serve as a weather tool. The artists, the late Anna Valentina Murch and Douglas Hollis, wanted these lights to represent a dialogue between the Willamette River and Tilikum Crossing — quite a poetic way to look at the lights, don’t you think?