Can you tell me what these things are?

I was scooting around town on my Hog today and rode down by Mitchell International Airport to do some plane spotting.

On College Avenue in Oak Creek, just a bit East of the MATC Aviation Center there is a bridge one goes under. I believe on top the bridge is a seldom used runway.

Anyway, when going under the bridge there are several devices that almost look like jet engines. Theres about 5 of them in each direction for a total of about 10 or so. There is some kind of turbo prop fan inside them, and they are functional.

Any idea what these things are, and what their function is? Does it have anything to do with the airport?

HERE are some pictures I took.

If I had to guess, I’d say they are ventilation fans for exhausting air from the tunnel.

At first glance that’s what I was thinking. But why would they need to exhaust the air in there? There are a couple of bridge tunnels like this in the Milwaukee area, and this is the only one that has these things (checked the other 2).
And why would the need so many? it’s not a very long stretch under there.

Or does it have to do with planes blasting their exhaust overhead?:confused:

They’re fans to prevent build-up of exhaust fumes from cars and trucks. Why only there? Maybe it’s more of a problem there due to local conditions. Probably it’s just newer.

I’ve seen them in a tunnel at Detroit Metro airport.

If it’s under a runway or taxiway, the fumes from jet engines could drop down into to tunnel. While probably not dangerous (I was an aircraft mechanic and smelled my share of jet exhaust), it could smell pretty bad and worry drivers who weren’t expecting it.

There’s also a very slight chance that a fuel spill could leave enough vapors in the tunnel to create a potential fire hazard. That seems really far fetched though.

Very possible. I don’t know when it was built but looking at the bridge it doesn’t show much signs of age or wear.

Here’s a PDF (I think. Takes a long time to load on my system anyway.) describing tunnel ventilation fans.

people look at those fans in the rest rooms and ask themselves, ’ where do those go?’. now you know.

are there adjacent enclosed parking or vehicle ways?

No. just the short tunnel and the runway over the bridge.

When my friends are in town, I tell them it’s “Jet engine storage”.
But I’ve been told they’re for when planes are sitting up there idling, it’s to keep the fumes for collecting under the bridge. However, you’ll notice they don’t have them under the bridge on Howell. I’m guessing this road under this bridge must be lower.
You may have also noticed that this bridge has a green arrow at the beginning. I have to wonder if when those fans kick on, they’ll stop traffic.
I’ve yet to see any planes land on or take off of that new part of the runway. The closest I’ve seen is one taxi up to it and turn around just short of it.

Here’s something else that’s really been bugging me about that tunnel, look at your picture #2/3. See that bank of lights closest to the wall. Just in front of it you can see a cable anchored to the ceiling. If you look at it (can see it in the picture), it goes along the ceiling and eventually goes to an electrical junction box. It looks like it’s designed to be pulled on to turn something on or off or stop/start something. There’s one on both sides (left and right) and North and South bound traffic. IIRC, each cable only goes half the length and takes two to span the length.

I notice that there appears to be a pedestrian walkway in the tunnel.

Personally, I’d be reluctant to count on being able to traverse the tunnel on foot without being harmed by CO and other exhaust products, were the fans not there.

They finished building it last summer (or the summer before). It’s very recent.

The other end of that bridge takes you to a roundabout and then a Speedway and a Falcon Fuel. I can see those gas stations from my backyard. Your trip probably took you about 100 feet from my house.

I’ve yet to see them running. They’re (from what I’ve heard) meant to clear out airplane exhaust and as I mentioned above, I haven’t see a plane on the section of runway. There is, however, more then enough airflow in the tunnel, just from the breeze, to keep the blades spinning though.

That sidewalk is just slightly more narrow than the average sidewalk. I’ve never seen anyone walking there.

Also, there is a sign inside there that says the area is under 24 hour video surveillance, and all illegal activity would be prosecuted. I wonder if anyone manning the monitors got jumpy when they saw me snapping pictures. I was openly carrying a Glock, too.

They ran for a while when I was there. There were no planes taxiing or anything. Maybe they’re on a timer?

Are they loud? Whenever I see them spinning I always roll my window down to listen for them but never hear anything. Between that and the fluctuating speed, I chalk it up to the wind whipping through the tunnel.

They could even be on a CO monitor. Though I wouldn’t suggest that only because the unwashed masses might freak out every time they turn on. Even if we were assured they were set well below the safe threshold, people still wouldn’t be happy about it.

Surprisingly no. For their size they are extraordinarily quiet. I was standing directly under them while they were running and the “rumble” they created sounded like the purr of a large cat. My white noise addiction fan in my bedroom I paid $16 for at Walgreens makes a louder racket.

Somewhat off topic, but do you ever go over to Warnimont Park in Cuda and watch the planes come in westbound over Lake Michigan? Sometimes it looks like they’re floating in suspended animation over he water. Really neat.

No, but I work at my family business on the Layton Ave across the street from the airport. I’ve been watching planes come and go for 30 years. Right now, I drive down Penn every day to and from work and see them go over my head all the time. I’d miss not living and working around the airport. All these years and it’s still surreal each and every time. Something that big shouldn’t be able to float like that.

When we were 16 and just started driving, we used to park up on Whitnall so we could see over the top of the airport. It was better then the observation area because you could see all the lights on the field.

Low-lying gases may be a reason in some areas, but mainly they are installed for smoke and fog removal during/after an accident.
This is merely a test, but watch towards the end; the smoke starts moving en masse for the exit which may be the other end of the tunnel, or a centrally located pipe that exhausts the smoke up a chimney system. With a 2 or 9 mile tunnel, you don’t want to push all that smoke all that way!

We have a couple of short tunnels here in Atlanta with ducted fans for ventilation, and they’re nowhere near the airport.

Traffic fumes and crash-smoke are their raison dêtre.

I asked a civil engineer. They’re called … wait for it … Tunnel Ventilation Fans. Used to move air, smog, fumes, fog, whatever you need to get out of the tunnel.

Heh. I grew up a Bender. Just a few miles outside the municipal airport out there. Our dear neighbor Floyd Gessert actually was the original operator of it. His grand boys Robb and Adam each soloed at 14 and are today professional pilots. Both were quite a bit younger than me and more close to my younger brother. But I did go up in a Cessna with Robb on a few occasions.

Point is, we got to see zillions of planes take off during the day, especially those pulling sail planes (“gliders”). At night I absolutely loved checking out the Runway scene as I called it. As a young boy I thought it was surreal and loved it!