Alabama STEM explorers is made possible by the generous support of the Holle Family Foundation, established to honor the legacy of Brigadier General Everett Holle and his parents, Evelyn and Fred.

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Engineering, math.

All coming up right now on Alabama STEM Explorers.

Hi, welcome to Alabama STEM Explorers.

I mentioned I'm here today a Bailey bridges at Fort Payne Alabama and my friend Gill.

So tell me about the company.

Well, Mitch, thank you for coming.

We're glad to have you.

Bailey Bridges does a variety of steel bridges.

Mostly what we do is like the bridge you see behind us here.

This is called our pioneer bridge model line of bridges.

And these bridges are for pedestrian traffic, mostly, sometimes large vehicular bridges.

This bridge behind us has got l structure with a concrete deck.

And you can see the wire mesh that goes over this because this is going over a road.

This is a highway overpass.

This particular bridge is going to Hattiesburg, Mississippi.

We do other bridges that you'll see that will have a wood floor or perhaps not the chain link fence going around it, but just a typical pedestrian handrail.

So there's a lot of options here at Bailey Bridges, no bridge is standard.

Every bridge is custom built for the owner.

This one is painted a shade of blue that I've never seen before, but that's what the owner wanted, so that's what we're going to give him.

So that's what we do here.

And you're going to see how they're engineered and designed, which is what we do here in house.

We furnish our customers the drawings.

Once they approve those drawings, we send the drawings after our shop and you're going to see how they're built.

And after they're built, we bring them out.

Sometithey get painted, sometimes they don't.

You'll see what a weathering steel finish looks like.

That's the most popular option we have.

And we have a paint shop here where we paint the bridges and after that we load them on a truck and they're going to ship to the customer and full pieces, just like what you see behind us here.

That's really cool.

So like, how long does it take to like build a bridge?

What are some of the steps?

Well, some bridges are big, some are small.

This one behind us is what we consider a big bridge.

It's 360 foot pieces, so roughly 180 foot span.

It takes that bridge, which takes about 5 to 6 weeks to go from start to finish through the shop.

And mostly the the finished work is what takes the most time in this case.

The painting and the install is the installation of the chain link fencing.

Most bridges can go through our shop in 3 to 4 weeks.

Okay.

Yeah, that's cool.

So, like, where have you shipped so these bridges and like what are some of the coolest ones?

Well, we have shipped bridges to all four corners of the nation.

A lot of them go to California, Washington, Maine, Florida, right here from central Alabama.

We go all over the country.

The majority of our bridges, I would say go actually to Texas or Atlanta.

But we have shipped actually one or two to Hawaii.

Really cool.

So like, how would you ship a bridge that big to somewhere like across the water?

Well, that's a bridge like that has to go on the deck of a ship.

So it's very expensive.

It doesn't happen very often, but it does happen has to go on the top of the containers of a container ship.

So like, what are some of like the obscure bridges or weird bridges that you've built in the past?

Well, we did a strange project.

We did was for a Super Bowl commercial.

We did a big teeter-toddler type contraption that was for a Toyota Tundra pickup truck to go up and over and back down.

In 2007, that was a Super Bowl commercial.

That's really cool.

Yeah, that was it was we've done some suspension bridges where we have cables that come down from towers and help hold the bridge up.

Those are some of our longest spans we've done up to a 270 foot Clearspan Bridge with the cable cable supports.

That's that's super cool.

What are some of like the materials that you use other than like the the obvious ones like steel and steel and concrete and wood for the flooring.

We've done fiberglass flooring.

We occasionally do different kinds of railings like aluminum or stainless steel railings.

Sometimes we do railings that have lights in them and LED lighting.

That seems to be something people like these days is the cool lights.

Yeah, we do some of that, that kind of thing too.

So what's like the biggest bridge you've ever built here?

The 270 foot span that I mentioned that had the cable stage supports?

That's we've actually done two identical bridges.

One went to Georgia, one went to Memphis, Tennessee, just like just like that.

So, like, how long would a bridge that big take to build?

That was bridge.

It took about 6 to 8 weeks.

Once they started in the shop, it took that long to build.

They're very big.

Yeah.

So like what kind of job jobs are there other than just like being in the office?

Well, there's any company has many jobs.

We have salesmen, people in marketing.

We'd go to trade shows, we have accountants, we have I.T.

people that just handle our our daily computer needs on top of the engineering and detailing needs.

Quality control is a big thing.

People don't get much exposure to that, I don't think, in school.

So we have certified welding inspectors, which is a career in itself, learning how to inspect welds.

Some of our wells have to be ultrasonic tested or even x rayed.

We don't do our own X-rays.

We have to hire that out.

But that is a career path.

People may not be aware of.

Yes, weld inspection.

So what exactly do you do here?

I'm the president of the company.

I'm also an engineer by training.

So on top of being the president and trying to run the company, I do get my hand in the engineering.

And we have another engineer, Alex, who you're going to meet.

He's going to show you how Bridges are designed.

Well, that's really cool.

Thank you.

And we have other tradesmen in the shop of welders, people who operate CNC machinery.

You'll see we have a CNC saw CNC plasma combined with a drill, plasma drill that we operate.

People who sandblast paint.

So there are a lot of trades in the fabrication process.

That's really cool.

Thank you.

Now we're here at Bailey Bridges with my friend Alex.

So, Alex, you're an engineer.

Tell me about what that's like.

Well, the primary purpose of an engineer is to solve problems and in my case, as an engineer here, Bailey Bridges, and on a day to day basis, figuring out and designing bridges, it's really cool.

So what kind of bridges?

Well, we do design and build all kinds of bridges.

Those include pedestrian bridges, vehicular bridges.

That's the two primary types.

But we also build bridges that might support different structures, light pipes and a whole host of other things, houses.

There's all kinds of different types we've we've worked with.

So you said pedestrian and vehicular.

What's like the difference?

And what are those two bridges?

Okay.

Well, a pedestrian bridge is primarily the intent is to move people from one place to another.

So if you could imagine, like if you're ever go to a bicycle or a walking trail.

Running trail, yeah.

That's where you would find pedestrian bridges versus a vehicular bridge.

That's more common on roadways when you're driving from place to place.

So like, how do you build bridges and like what what are those steps that.

Yeah, so the first the first step is you have to know the purpose of the bridge, which like kind of mentioned earlier, we have to know what the bridge, where the bridge is going, what the purpose is, is in, is it crossing a river or a stream or is it going over a roadway?

That's that's several, you know, purposes of bridges.

And then we move into a design a design stage where we actually go from what the purpose is to determining, you know, the length of the bridge, the width of the bridge, how much load capacity the bridge has, has to be able to to to support.

So once we've established all that, we're able to go from from just what the the that is knowing what we need tsign for to actually putting a design in our in our computer modeling or on our on paper.

So yeah.

So like, how do you know if like a bridge is sturdy or something like that?

Well, there's, there's different, different ways.

But primarily as an engineer, you know, what I learned about in school and then here on the job is, is how we use math and physics to to to analyze a structure of, you know, when I was in school, I was able to take a lot of classes in college classes, primarily.

That taught me how we can can actually analyze and design a bridge.

And then, of course, here on the job, I learned a lot more about it and I'm able to do it both.

Primarily, we were able to do most of it on soft computer software now.

So what are these bridges most of the time like made out of and like, how does that change how you build it?

Great question.

So there's several different materials that bridges can be made out of.

What we primarily work with here is structural steel, which you're probably familiar with, but there's also concrete bridges.

There's even some bridges that are made out of a type of plastic.

It's called fiber reinforced plastic.

So we don't work with those as much here.

Mainly steel bridges is what we work with.

Yeah.

And like what?

Like how would you decide which type to use?

You know, well, there's different factors in many cases.

It just it would just depend on sometimes the owner's preference.

If they have a preference of material, but also how long the bridge is, how wide the bridge has to be.

And sometimes even where the bridge is located, can can be, can influence what type of material is used.

Yeah.

So like this company in particular, what kind of like what kind of bridges have you been to?

What places have you made them?

Sure.

So we have we mainly use steel.

Steel for our for our bridges that we fabricate here.

And we have shipped bridges all over the U.S., all over the primarily the 48, 48 contiguous states.

So but we do them we've done a lot of bridges and mostly of steel.

So you're imagining some stuff about like physics earlier.

Can you show me a little bit?

Sure.

What I have here, Mitch is is a soft some software that we use to actually model bridges.

If we can imagine, we can actually model each member of a bridge and then apply a load like we were talking about, whether it be a vehicle load or a pedestrian load or even wind loads, stream loads.

There's there's a lot of different loadings that we can apply, but we can actually draw each member of the bridge and then apply the loads and in actually have a model and see how the structure reacts to the loading.

And there are different design codes that we have to design our bridges for depending on where they're going and who the owner might be.

But but basically what we're doing in the software here is we're checking and analyzing that structure to make sure that it will it will operate satisfactorily for and not fail under those design loads.

So you said some definitions, some words like numbers and loads.

So like, can you explain those?

Sure.

Let me just show you.

Yeah, this is so like I mentioned, this is a bridge that we have model in this software and this is what we would call in.

What we primarily use here are truss bridges.

And so there's a couple of truss as you can see.

So what we're looking at here is like we're looking from this from the side of the bridge, okay?

And this is a truss and we have what we call diagonal members, which are the obviously the diagonal lines that you see.

And then there's these horizontal members or the main chord members of these trusses.

And so when the when when the load is applied to this bridge, then each of these members helps resist that load.

And so when we're designing the bridge, we're making sure that each individual member is not being overstressed.

You know, by that loading.

And so you can see here, I've drawn in a few of these diagonals and I can show you, we can go in and zoom in here and I can actually select these, these individual points on, on the, on this truss in and and diagonals.

That's cool.

So you can make more members.

Exactly.

Yeah, that's exactly right.

So basically, like the load is just like the weight in the pressure, like.

Exactly.

That's exactly right.

It's the it's the weight of the of the bridge plus the weight of any other things that are going to be applied to the bridge or on the bridge.

Yeah, that's exactly right.

It's cool.

So, like, how do you know when a bridge is, like, starting to rot or deteriorate?

Well, in our country and you've probably heard there's a lot of bridges throughout the US that are that are not that are in poor shape.

And that may be a good reason why you're asking that question.

And it's a really good question.

Well, fortunately, we have in our country a bridge inspection program that has really become more and more, I guess, popular.

Well, more more and more widespread, I think in the recent years.

And what what that consist of is thererograms in place that train people that can go out and inspect bridges and look for different areas on the bridge that might be prone to deterioration or causing failure of a bridge.

And so, you know, there's there's many different things that can can cause a bridge structure to be weakened.

Corrosion on steel, like rusting steel that's not properly properly protected.

That's one one case that, you know, that I'm familiar with being a steel primarily designing steel bridges.

But the same can be the case for a concrete bridge.

There are different areas that these inspectors know that they need to really be mindful of and inspect closely when they go out and do their bridge inspections.

So like on average, like how long with like a steel bridge last before it starts becoming hazardous?

Typically, the design life for for a bridge is usually 75 years.

So it's, it's in if it's if it's taking care of it could they can last even longer than that.

So it's all in how it's designed and how it's protected and how it is maintained that can really dictate how long it will last.

So like what makes a bridge high quality like, well, there's different, different coatings that can be applied to bridges there, you know, having a regular inspection program helps improve the quality of a bridge because things if there are things that are maybe that would contribute to deterioration, it would it would bring it to light sooner than if it wasn't in an inspection program.

And yeah, that's 2 to 2 main ones that come to mind.

So like what kind of science, technology, engineering and math goes into building bridges?

Wehonestly, a little bit of everything.

You know, science as far as physics is a big part of of designing of designing bridges.

So I would say regarding the science, it's definitely heavy in physics, technology.

You know, there's new technology all the time, but especially, you know, like the software we've talked about this modeling software that we use is is certainly technology that's improving and becoming more readily used every day.

Engineering, you know, engineering is really the core of of a bridge design like a we've talked a little bit about I had have an engineering degree in an engineering professional engineering license which certainly qualifies me, you know, as far as being able to do bridge design for for my for for for a living.

Yeah.

And then math really is the foundation of of of of bridge design and really engineering in general, having a background in math and being able to, to apply that on a daily basis to, to design problems and equations that I have to do in my bridge design.

So STEM is, it is very much prevalent in, in, in bridge design.

In engineering in general.

Yeah.

Well, Mitch, I can show you things here in the office, but to really see how a bridge goes together, I'd like to take you out into our shop and actually show you bridge is being fabricated.

Hey, Mitch, here we are on the floor.

We actually fabricate our bridges.

Right behind this here is a bridge that we're fabricating to go to Dallas, Texas.

That's cool.

Yeah, this one is as a wider bridge that you could actually carry a vehicle across.

But we also do, like I was mentioning earlier, a lot of bridges that are for like trail and rails or I'm sorry, trail rail to trail bridges easily.

But like an example in Alabama is the Chief Ladiga trail.

I saw that before.

Yeah.

Down around Piedmont and Jacksonville, those bridges are more intended for bicyclist and pedestrian use.

Like we were talking about.

Yeah.

The ones that I can show you on this bridge behind it, you can see the members that we were I was showing you on the computer, all the software that I was modeling, the bridge on.

You can see like the diagonal members and the board members and all the bracing that goes in between.

Yeah, that's cool.

So like does that all steel this bridge is all steel and it's a pretty large bridge and you can tell it's pretty wide.

So this particular bridge can be disassembled and shipped to the job site where it'll be installed by a contractor and then later use by pedestrians are vehicles.

Yeah.

So like how long would it take to make a bridge like that?

This bridge, as far as fabrication, probably would only take a couple of two, maybe three weeks once it gets in our shop here.

Now, from start to finish, it's probably from the time we started design to the time it actually gets installed.

Probably more like eight, ten, 12 weeks.

Yeah.

And how does why do people come here?

You guys are like, why do like yeah, people come to us really because they know this is kind of our specialty that we really only do bridges.

So they know when they need a bridge that that looks like this and that meets the needs that that they're needing.

They'll, they'll call us.

So like how many places like this are there like in the US?

Well, voices that do exactly what we do as far as the steel pedestrian and vehicular time bridge is probably not many of that.

But there's maybe eight or ten in the US.

Yeah.

So are you guys the only one in Alabama?

No, there's a few in Alabama.

Oh, okay, cool.

Mitch, I'm not going to let someone else that I work with here.

His name's Gill.

Take you outside and show you some of the bridges that we built and are actually finished and ready to go to the jobsite.

Well, thank you.

Thank you.

So tell me why all these bridges are out here.

Well, these bridges have just been built within the last month or two.

They are waiting to be shipped every bridge is built specifically for a customer.

And these you see over here behind you, you have a sort of an orange tent.

They they've just come out of the the fabrication process.

They've been sandblasted.

And as soon as the customers are ready to take delivery, we'll bring our forklift out, pick the bridge up and put them on a truck, and they'll be shipped to the job site and he sections you see here and bolted together if they're multiple pieces.

So what exactly is the fabrication?

That's the part.

After it's designed and engineered that it goes into the drawings, go to the shop, we take the raw materials and weld cut and weld everything together into the big pieces you see ready to be delivered.

Yeah.

So I feel a lot of like rust and stuff on all these, right?

These bridges are weathering steel, unlike the first bridge we saw earlier that was painted that blue color.

These bridges are made out of what we call weathering steel.

Weathering steel is a certain type of steel that has certain alloys in it, like copper or silicon, magnesium, manganese.

And those alloys help the steel create a very fine, tightly adhering coating of rust so that outer rust actually protects the steel from further rust.

This deal in the correct environmental last over a hundred years, as long as it's not corrosive like from salt water or a bad industrial uses these bridges behind you have been weathering for only about a mile so they have an orange tint things tell their steel weathering after they've been sandblasted.

This bridge over here has been out about eight or nine months and it's probably weathered all it's going to weather.

You could rub up against that steel and get a little rust, the little dirt on you, but no rust.

The rust does not come off really.

So that's what that is.

So like, I see this one's wooden and this one's like metal, right?

I think it's going to have concrete.

So why would you choose one over the other?

Right.

We build these for a concrete deck.

That's really what the customers prefer most of the time, concrete.

And so it's ready to be poured.

Want to install the contractor at the job site will put a concrete deck on that right on on there these bridges that are we would like this one over here.

The wood is installed here at the factory.

So once it's delivered, you can drive and walk on it right away.

And so the wood is a little more economical because you don't have to get a concrete truck to the jobsite, but every 20 to 40 years you probably have to replace the wood.

So that's a trade off, but that's the customer preference.

And the wood we usually use, like you see in this bridge behind me is southern yellow pine.

Most times the customers specifies a Brazilian hardwood that's very popular called EPA.

And you'll see that on boardwalks in big cities.

Sometimes it's a very dense kind of wood and very durable.

Very strong.

Yeah.

So like how many different types of wood would you like?

How many kinds?

Well, there are there are a lot of different wood.

You know, there are cedar.

Oak Doug Fir is a very popular when the oak and the cedar is not very popular.

But we have done those.

They're they're not common for this kind of application.

Southern yellow Pine and Douglas Fir we see out in the northwest region of the country are the most popular.

Well, yeah, thank you so much for having me today.

And I've learned so much, so, so much cool things about bridges that I've never, never would have thought about all the STEM and science, technology, engineering and math that would be involved in building bridge building.

Well, there is a little more to it than meets the eye.

Mitch, we've been happy to have you, and I hope you've learned a little bit.

And I hope everybody out there has learned a little bit about how bridges are built and and the engineering process behind them.

Well, thank you.

I'll see you next week on Alabama STEM explorers things that are watching Alabama STEM explorers.

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Alabama STEM explores is made possible by the generous support of the Holle Family Foundation, established to honor the legacy of Brigadier General Everett Holle and his parents, Evelyn and Fred Holle.

Champions of Servant Leadership.