BETTENDORF, Iowa — Work on the color-changing LED lights that line the new I-74 Bridge is nearing completion.
Over the next few weeks, the bridge will be lit up in different scenes from sunset to sunrise to allow the U.S. Coast Guard to collect feedback from barge captains. The project team will review and adjust the lighting intensity if necessary.
It's one of the last steps for the lighting project that began in 2011.
Elizabeth Johnson has been the project manager on the design team with HLB Lighting since the beginning.
"It's just a great expanse and making sure that this all is connected and working together - that was a challenge for this project," Johnson said. "But I think we've put it together and that the builders have done a great job installing it, and it's looking really good."
The entire I-74 bridge has about 1,000 lights on it, including street lights, approaches and white lights on the piers. A lot of thought as gone into every aspect of the bridge, even the street lights, which were designed with a curve to reflect the curve of the Mississippi River.
But the colorful lights on the arches come from more than 200 circular luminaires lining the floor of the bridge.
Each luminaire contains red, blue and green lights. Mixed together at different intensities, the three colors can create all the colors of the rainbow, Johnson explained.
"When it comes to color mixing with light, it's additive," she said. "It's sort of the opposite of paint. So when you mix two colors of paint together, you take your red, you take your yellow and you get orange. But when it comes to light, if I take a red light and I take a green light and I mix it together, I actually get yellow."
HLB Lighting Principal Faith Baum said having the lights shine up from the floor beams on the roadway helps get a smoother wash of light on the arches.
"We're controlling the light to a big degree as well and really making sure that what we're lighting is the arches and not just spewing a lot of light into the atmosphere is something that we really try very hard to avoid," Baum said.
The lighting technology has also changed since the designers put together the initial proposal.
"We designed the lighting for the time using color-changing lighting technology," Baum said. "That technology changed and morphed over the years after we finished the preliminary design, and so we had the opportunity to update it a bit before they finally purchased and installed it."
The LED lights have about 100,000 hours of burn time before crews will have to replace the luminaries, Geoffrey Thiesse said. He was the electrical engineer for the project with Alfred Benesch & Company.
While Bettendorf and Moline both share custody of the I-74 bridge, the lighting server that's used to program and control the bridge lights is housed in Bettendorf's City Hall.
Thiesse said Bettendorf was chosen because the bridge lights were originally going to be controlled with a wireless system that would require line of sight, and Bettendorf's City Hall was better than Moline's.
However, due to the construction of The Bridges lofts in 2017-18 and the removal of a city hall antenna, Thiesse said they had to switch from the wireless system to a fiber optic one instead.
The bridge is currently programmed with 26 lighting scenes.
"It all depends on what's important," Baum said. "That's part of what makes it so much fun is getting to work with the people who are going to be enjoying this and really reflecting back and giving them opportunities to do things with the bridge that they might not have even realized was possible."
The lighting server is a simple laptop. Bettendorf and Moline's employees have been trained to use the technology to create and operate the lighting scenes.
"We're really going to try to make this as automated as we can, so we're not messing with it on a day by day," Bettendorf City Engineer Brent Morlok said. "We're gonna have a quarterly scene is what we're calling them. They're kind of seasonal, so you're gonna have a winter, summer, fall and spring season. Each of those has a little bit of a dynamic scene to it, so you will see some motion in the lights."
I-74 Bridge lights shine bright
Each scene will be up for three months. For example, the winter scene is a mixture of white and blue colors.
The I-74 bridge is also programmed to light up in special colors for the federal holidays or special events in the Quad Cities, such as the John Deere Classic or the Bix 7 race. It even is programmed to light up in the University of Illinois or University of Iowa colors.
"It's going to be iconic for our area, and this just adds another level of cool factor to it really," Morlok said.