Five questions with the steam tunnel tour guides

Murray and Frost in tunnel

When campus groups tour Iowa State's steam tunnels, the guide is either manager of mechanical distribution David Frost (left) or Mike Murray, director of engineering for utilities distribution. Photo by Christopher Gannon.

Most faculty and staff work on campus. Mike Murray and David Frost work under it. They lead facilities planning and management efforts to plan, construct and maintain utility distribution systems, nearly all of which are below ground. As director of engineering for utilities distribution, Murray coordinates utility service for large projects. Frost, manager of mechanical distribution, oversees field operations and maintenance.  

The basics

Name: Mike Murray
Position: Director of engineering for utilities distribution
Years at ISU: 25

Name: David Frost
Position: Manager of mechanical distribution
Years at ISU: 8

But for the 60 quick-acting employees who managed to secure the most in-demand offering of the inaugural Faculty and Staff Appreciation Week this spring, Murray and Frost might be better known as the steam tunnel tour guides. Slots for the appreciation week's four steam tunnel tours filled up the same afternoon they were made available.

"We were kind of strutting around a little bit about that," Murray said.

Murray and Frost alternate in leading tours of the tunnels, a sprawling network of subterranean structures built to house the pipes that deliver high-pressure steam to campus buildings. The passageways have been around nearly as long as the university and have expanded as the campus has grown, protecting pipes that take steam from the power plant to buildings -- primarily for heat and hot water. The first steam tunnel was constructed for Marston Hall about 120 years ago, and the most recent addition serves the Student Innovation Center.

Inside caught up with the steam tunnel experts recently to talk about their hot-ticket tours.

When did the steam tunnel tours start?

Murray: I’ve been here 25 years, and we did not do them for a long time, for no particular reason. Then about 15 years ago, I started giving the tours to student organizations. Honors groups and civil engineering groups, people like that. It was kind of a trickle, one or two a year. When Dave came eight years ago and became familiar with the system, he started doing some, too.

Frost: We started getting more interest, about that time. More interest than you could really handle.

Murray: And then after the staff appreciation week, the word must have gotten out. We have seen an increase in requests. We have had to be just a little bit more selective. We had one group that wanted to bring in 80 people in one afternoon.

Interested in a tour?

To arrange a steam tunnel tour, email Mike Murray at or David Frost at The maximum group size is 15 people.

Why do you think people are so intrigued by steam tunnels?

Murray: Because of the mystery, from what I can tell. If you’re used to it, this is old hat. It’s a white hallway with pipes in it.

Frost: There's always somebody in the group that says, 'Well back when I was in college, we would try to enter the steam tunnels and check them out.'

Murray: There's a lot going on underground, but most people don't see that when they're walking around on the sidewalks. Their eyes are a little bit higher up or on their phones. They don’t notice the manholes, the little round iron discs over shafts that go down to domestic water valves, the rectangular hatches for the steam tunnels.

Frost: For us, the tours aren't just about the steam tunnels. I get to talk about all the other services that people take for granted. You turn the faucet on, and the water magically appears, right? I like to talk about the process of how it gets there. That’s why I enjoy it so much.

What kinds of questions do people ask?

Frost: I think the question we get asked the most is whether we use the tunnels to get across campus. Me? Absolutely I do. If it's 20 below out, I can walk into a tunnel and pop out in almost any building where I have a meeting. Do we allow anybody else? No, we don't.

Murray: There was an undergraduate student who had a research project proposing how we could convert the tunnels for pedestrians to use. There's not enough room, and I can just imagine that conversation: 'Your daughter was last seen going into this tunnel.'

Frost: I get asked about critters quite often, but we really don't have many problems with that. I always say we send in the tallest guy first to get rid of the spider webs. And every once in a while, an industrious ground squirrel will store their nuts on top of a warm steam line.

So why are tunnels better than burying steam lines?

Murray: It's a debate in the industry, but tunnel systems have a much longer life. And you can maintain them without disturbing the populace. Steam pipes inside our tunnels essentially have an indefinite lifespan. We see little signs of wear or aging. The buried pipes have a lifespan anywhere from five to 40 years. It's a wide range because it depends on how well it was installed, the soil type and whether it gets damaged. If someone's digging and they hit a steam tunnel, it goes clunk because they've hit a concrete wall. If someone comes through boring a fiber line, it can scrape through the insulation covering a buried steam line and damage it without us even knowing about it. Down at the Iowa State Center, the steam lines are buried. By 2015, that was a 50- or 60-year-old system, and it was failing all the time. We would be down there digging two or three times a summer to patch it. That would be a bit disruptive on campus. We've replaced all of the Iowa State Center system now. And it will have a five- to 40-year lifespan.

What's your favorite story to tell about the steam tunnels?

Murray: I'd say the fact that the first tunnel built on campus was made from arched brick and is still in pretty good shape. We can't get structural engineers to design us brick tunnels anymore because there are no design codes for them.

Frost: I always thought it was interesting, and I credit Mike for first noting this, that the powers to be who built Iowa State's power plant put it way, way, way off campus so there wouldn't be students around it. We've got old pictures where there are sheep out in fields where the plant is. That decision helped build the foundation of the steam tunnel network.