This is 99% invisible. I'm Roman Mars.

We talked to a lot of architects on the show, but this week we're talking to an engineer.

My name is Mark Blasjak, and I am a professional engineer in the state of Texas.

He's like really from Texas.

Yes, yes, I'm a fourth or fifth generation Texan.

I've forgotten which one.

But I've been raised in other parts of the country too

so I can talk to talk because I have been raised in the East Coast you know.

We talked to Mark about one of the first projects that he ever worked on.

That's producer Emmett Fitzgerald.

He had just graduated from college at the University of Houston and he'd gotten a job in Austin with the Texas Department of Transportation.

And I was in my mid-20s at the time, so 40 years ago.

Actually, I like to say four decades, it sounds like less.

I was assigned to a number of things, but I ended up on the Congress Avenue Bridge,

that is the reconstruction of the Congress Avenue Bridge.

The Ann Richards Congress Avenue Bridge.

The Ann Richards Congress Avenue Bridge

is just a simple concrete arch bridge

that spans Lady Bird Lake in downtown Austin.

The bridge was completed in 1910, but by the late 1970s it was in need of a tune-up.

It was structurally deficient and so it was rebuilt and more conventional more modern more contemporary beams were put in called box beams

The box beams sit below the road surface and they need to be spaced a certain distance apart.

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