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Ken Peoples wrote:

"...Just out of curiosity, why do you think that many very well
qualified bridge
engineers would think twice about taking on a 500' span bridge - or are
talking about bridge engineers who do everyday standard DOT 20' to 100'
boring precast concrete bridges that are already basically designed for
by the precast concrete manufacturers?  That would not surprise me if
an engineer - who does not think outside the box of standards - would be
afraid of this.  I would think that if I considered myself a very well
qualified bridge engineer (which I do not), I would love to have the
opportunity to work on a project like this.

Thanks for the leads on the other structures.  I wonder why they thought
they needed a post office over the railroad tracks.  Sounds interesting
- I
hope I can find both of them."

You're right, there are a lot of bridge engineers who do primarily
standard precast beam bridges.  And you're right, a lot of them aren't
particularly good at thinking outside the box.  A lot of them would be
very nervous attempting such a project.  There are a lot of other bridge
engineers who operate in what I think of as the next plane--they design
the big steel stringers or concrete box girders.  I consider someone who
does this for a living as being a pretty well qualified bridge engineer.
But this experience may not equip them to design 500 foot spans; steel
stringers in a practical depth range can't be pushed out that far.
Maybe a concrete box could--I don't know.  Otherwise, as I said, that
calls for a truss or an arch.  And in my opinion, there aren't too many
people out there who are qualified to design these.  I know I'd
hesitate.  If you're going to spend $100 million of someone else's
dollars, I think you owe it to them to either really know what you're
doing, or get out of the way.

As far as the other structures, if I remember, the Post Office placed a
lot of value on this particular site because of adjacent infrastructure
or access to the railroad or something else, so they bought the air
rights over a big switching .  It was long enough ago that I don't
remember much else.  I just read about it; I wasn't involved with it.
And I think the McDonalds was built on an old prestressed beam highway
bridge.  (I know it's a prestress beam bridge; it looks like a highway

Finally, I owe you an apology.  I didn't mean to sound so critical; and
as I said, I do a lot of small mezzanines in addition to the bigger
stuff.  For what it's worth, I used to do a lot of bridges, too.  The
other guys I worked with had had it beaten into them to let somebody
else do the creative thinking; they loved their two-span prestressed
grade separation structures.

They weren't much fun to go drinking with either.

Chris Towne wrote:
"This is a very professional response.  Much more than what mine would

Yeah, probably mine too, if the situation was reversed.

Michael Hemstad, P.E.  
Saint Paul, Minnesota 


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