As summer turns to fall, Missouri prepares to celebrate many traditions—fall festivals, hayrides, and pumpkin patches. A lesser-known tradition for many may be the Arch Builders event, hosted at the St. Louis Arch every October. At this special event, the National Park Service recognizes the many people who labored together to accomplish the “impossible”—constructing the Gateway Arch in St. Louis. Amongst the hundreds of workers on the project was native Missourian Jerry Mundy, the man who calculated the size of the HVAC fans required for the colossal monument.
In 1965, Jerry graduated from the University of Missouri and was offered a job with Trane Technologies. As an excited and young twenty-something, he accepted the position, never dreaming that he would soon be working on a world-famous project.
Trane Technologies assigned him to its St. Louis office, a satellite location of the company. “When I got there, a senior guy with the company told me that Trane just got a bid and sold a bunch of equipment to the Arch. He said to me, ‘If you want to go with me to the Arch, you can.’ I said, ‘I’d love to.’ ”
That November, Jerry was given one task: calculate the fan size for the HVAC (heating, ventilation, and air-conditioning) systems for the 630-foot-tall Gateway Arch.
A complex system
Though it might have been a seemingly small job to someone on the outside, Jerry knew he was being handed no simple task. “The fan system is a really big deal,” Jerry emphasizes. “These things are not like fans you see every day, and they’re not even like centrifugal fans—the circular kind—these are massive systems that move the air up one side of the arch and down the other.”
Sophisticated HVAC systems needed to be built to keep the Arch’s temperature stable. “Little doors [in the inside of the system] open up and inject more cold air in the summertime to keep the temperature right. That way, you’re not having too much of a temperature rise. That’s all part of designing this fan system. It’s a pretty important piece of the arch,” Jerry says. Although this is a complex design even for a seasoned 78-year-old engineer like Jerry, at the time he was tackling it as “a confident, young little baby just out of school.”
A large miscalculation
When it came time to design and calculate the numbers for the HVAC systems, Jerry knew that nothing like this had been done before. Regardless, he was confident that he would be successful. “I sat down at my desk to start to do the calculations, and I looked, and it [the engineering specifications] was expressed in feet of static pressure instead of inches of static pressure. But, you design the system based on static pressure, and static pressure is expressed in inches per square foot. I said, ‘Feet of static pressure isn’t possible.’ You know, ‘Someone made a mistake here.’ And so I based all of my calculations on inches,” Jerry says.
He then sent his completed set of calculations for the HVAC systems to the team of Eero Saarinen, the famous architect who created the Arch. “He was the lead of it all, and all of my stuff came back with red ink,” Jerry says. “That was kind of embarrassing, and yet, I was pretty hard to embarrass in those days. I was just like, ‘Well, okay,’ You know, ‘Let’s do it again.’ ” And so he did. After redoing the entire set of calculations, changing the static pressure to be measured in feet, Jerry sent them back to Eero’s team, and they were approved. Jerry says he’s extremely glad that the miscalculations were caught then, as Trane Technologies would have fabricated and attempted to install a multimillion-dollar system that would not have functioned correctly.
A searing steel arch
Construction began in February of 1963, and as the crew worked into the summer months, Jerry’s participation in the project became even more essential. His work with the HVAC fans was time and temperature sensitive and had to be coordinated with other aspects of the construction.
“Think about this thing,” Jerry says. “It’s a stainless-steel arch with summer temperatures that reach into the high nineties, and it can’t be 150 degrees up there. If you had no air conditioning inside of it, you could not survive in it. It would cook you to a crisp.”
—Jerry Mundy
“Think about this thing,” Jerry says. “It’s a stainless-steel arch with summer temperatures that reach into the high nineties, and it can’t be 150 degrees up there. If you had no air conditioning inside of it, you could not survive in it. It would cook you to a crisp.”
In fact, the Arch was so sensitive to heat that the engineers had to place the very last hundred-ton, steel-wedged piece in an unconventional manner. While many structural projects finish with the last piece sliding in as a perfect fit, this wasn’t the case for the Arch. When it came time to place the last section, it would not slide in like all the others had. The hot temperatures of the summer months now worked in the crew’s favor though, allowing the metal to expand. The two legs of the arch were pulled apart like a pair of pliers, and the last piece was wedged into the slightly softened metal, creating a secure fit.
An overarching experience
Despite his months in the office spent hunkered down with pencil and paper, making calculations, Jerry’s job offered some lighthearted moments away from his desk.
He remembers vividly the day he asked a supervisor, “Hey, is it okay if I do a climb to the top of that [the Arch]?” and he replied, “Sure if you’re willing to try it. Go ahead.” (This was before the train system was installed that would work like an elevator and take future visitors to the top of the Arch.) And so he did, his supervisor Joe tagging along. Together they climbed the 1,076 stairs to the Arch’s crest. These two engineers from Trane Engineering were among the first people to view the city of St. Louis from the Arch at 630 feet above the ground.
Jerry says the St. Louis Arch was a marvel in engineering and architecture, and that it still is today. “Sure, the science told you what to do,” he says. “Except everywhere along the way, the science said, ‘Wait a minute, things are changing here.’ ”
Jerry is grateful he was able to participate in the project with Trane Technologies. “This was all stuff that had never been done before, you know. Companies went out of business just trying to do their part. They bid for the job, they got it, and then they realized they couldn’t do it [financially].” Jerry got to see his part of the project through to the end, and today the Arch still stands strong.
The construction of the now world-renowned monument that was once thought to be an impossible feat wouldn’t have been possible without pioneering engineers like Jerry. The Arch’s one-of-a-kind HVAC systems have been updated from time to time, shifting with technological improvements and engineering breakthroughs. But one thing is certain, Jerry’s calculations and perseverance have been keeping the Gateway Arch comfortable and cool for visitors since the day it opened, making the smiles on their faces possible.
The annual Arch Builders event has been free and open to the public in past years. Information on the October event will be released on ArchPark.org/events/all in early September.
This article was originally published in the September 2024 issue of Missouri Life.
