Elation revitalises St. Louis Gateway Arch
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‘The Arch’ has stood on the banks of the Mississippi River in St. Louis since 1965 as America’s symbolic ‘Gateway to the West’. The Gateway Foundation, a private non-profit that first lit the structure in 2001, funded the lighting upgrade. Under its direction, TPI spearheaded the specification, design, and installation of the new lighting system with focus design provided by Randy Burkett of Reed Burkett Lighting Design.
Burkett was hired by the Gateway Foundation to light the Arch back in the late 1990s, a design that included luminaires installed in underground pits, then renewed the lighting several years ago using 7K xenon sources. Michael O'Keefe, COO of TPI, proposed a lighting upgrade after years maintaining the outdated xenon lamp lighting, a system that was not only proving unreliable and expensive to upkeep but wasn’t showing the Arch in its best light. “Parts were breaking and the cost in lens filters and lamps, not to mention the labour to change them, was very high,” O’Keefe stated. “I truly felt that we should honour our monument more consistently and more efficiently with the best available fixtures.”
The solution lay in Elation’s Proteus Brutus, an IP65-rated automated light with a high efficiency 1,200W peak field LED engine and 75,000 total lumens of output. The fixture, part of Elation’s weatherproof Proteus line which TPI has used on previous projects, was selected after careful consideration of its specification and a successful on-site test. “The on-site tests were pivotal to the acceptance of the product,” Burkett remarks. “It was the only way to prove that the intensity, beam management, framing, CCT and other key parameters would fulfil the needs - which they did.”
Nick Vincenty, director of system design and engineering at Technical Productions, was heavily involved in the project and touches on the challenge involved. “We needed to shoot 650 feet straight up at a target 25 ft wide, which isn’t an easy thing to do. This was the first fixture we saw that not only had the output to do it but the zoom optics to do it accurately, plus it’s IP65. It’s really the only LED fixture that met the requirement.” O'Keefe adds that they looked at other fixtures but that nothing compared to the Proteus line. “I had a lot of confidence in it and a lot of confidence in Elation.”
The Gateway Arch is a complex shape - a weighted catenary arch 54ft wide at its base narrowing to 17ft at the top. Clad in stainless steel and 630-ft tall, it is the world's tallest arch. To light the structure, 76 Proteus Brutus fixtures were placed in four existing lighting pits at the legs of the Arch, each pit covered with 12 circular slotted grates to shoot light through. The slotted grates are individually rotatable to maximize louver orientation efficiency. The pits were modified by TPI to house the 104-pound Brutus fixtures (previous fixture weight was 450 pounds!) with strut rails added that run the length of the pit to allow the fixtures to move when needed for focusing.
Vincenty explains that the Brutus fixtures that shoot to the top of the Arch are zoomed at four degrees with the zoom angle widening as you work your way down the Arch. At the base, the angle widens to approximately 22 degrees (the Brutus can zoom out to 45 degrees). “The previous 7K xenon fixtures could only zoom with special filters which wasn’t very effective and we ended up losing over half of the lumens into space,” he said. “The fact that the Brutus can easily zoom to put all of the lumens on the Arch was another key selling point.”
Burkett adds that the original mock-ups from the original design process proved to be invaluable, as they found that the lighting reflections off the semi-specular Arch surface had to be managed, making certain that they would fall in areas that would not be unsightly or glary.
The Proteus Brutus’s intelligent controllability gave several other advantages over the previous 7K xenon fixtures such as the ability to dim, focus and colour correct more precisely. Pinpoint focus accuracy for example means there is much less overshoot so much more light is concentrated on the Arch itself, minimising direct spill lighting into the sky. O’Keefe comments, “We then have the ability to manipulate that by frosting and smoothing it, plus we’re using templates to elongate the beam and concentrate the light onto the Arch itself.”
The new lighting system has resulted in substantial power savings, with the LED fixtures consuming only 1,200W per unit compared to the previous arc source units at 7,000W per unit. This 60% reduction in power consumption, coupled with the elimination of frequent lamp changes, contributes to significant savings in both energy and costs. Moreover, the Proteus Brutus incorporates a ‘sun protection’ feature, ensuring the longevity of the fixtures by pointing the lens towards the ground in the event of control signal loss, protecting the lens and components inside the fixture against sun damage. The new Proteus lighting system made its debut on 19 December 2023.
