Just FYI, thenā¦ the highway near your old office has officially become an āopen source meme templateā.
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Itās an old picture. That bridge was replaced in 2011ish. The DMS is no longer there.
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I donāt even know where the original pic came from. Just found it on a random website for creating fake road signs.
To me, it looks like almost any typical stretch of I-270 in Ohio on any typical winter day.
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Itās west bush lake road over I-494. You can see the street name on the sign. Plus, as Iām a highway engineer, there are other tells I could see.
And if it were Ohio, that would be a steel girder, not concrete. 
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Weāll Iāll be a monkeyās uncle.
Iāve lived here for nearly 20 years and never noticed that fact until you pointed it out. Theyāre painted a concrete-ish color, and Iām usually rushing past them at about 80+ MPH, so never paid close enough attention myself. But a short little drive via maps street view appears to confirm that you are correct. All the ones I checked are actually steel.
Good eye! Or, I suppose in your case, seeing as youāre something of an expert on the subject, good knowledge!
Total side off-topic questionā¦ is there a reason why one would be preferable to the other? I.e., is one cheaper than the other; one better built for high winds, one better suited for earthquakes, etc.?
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Local industries. Ohio is steel country. They are doing more concrete now, but itās new to them. MN will do all concrete unless itās curved or a longer span, but even those are going more concrete with more efficient designs and materials.
And Iām talking about typical structures. Long spans are a different animal. But in general you see more concrete out west and more steel back east in the states.
In MN, some might express concerns about maintenance on a steel bridge. I worked on a bridge over I-75 in Montgomery county Ohio (I think that was what it was, we called it MOT 75) where ODOT wanted extra clearance as they were concerned on maintenance of a concrete beam if itās ever hit. That was a new one to me. A lot of this is very regional.
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Makes sense.
I grew up in S. California where I was used to seeing concrete everywhere. Looking back now, that seems a bit odd, as I didnāt think concrete was exactly an ideal building material to use in an area that is highly earthquake proneā¦ but apparently it worksā¦?
And yes, I-75 runs through (and intersects with I-70) in Montgomery county. Used to live there myself, just north of Dayton.
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CA is unique. They do cast-in-place box girders. Basically, if you look at it from the bottom, you donāt see the beams. You see the āsoffit.ā The ābeamsā (or stems) are cast with the soffit then the deck placed on top creating a bunch of voids. The plywood used for the deck is super cheap as itās abandoned - I always avoided walking on that as much as possible (used to work construction for Caltrans). The contractors in that region are set up to build those cheap but itās like the only place in the states - that type of construction tends to be more expensive everywhere else where they do more precast.
For earthquakes, itās really the columns that are prone. Think the cypress structure in Oakland 1989 or Northridge 1993 where single column structures collapsed. They design them with weaker spots such that the area where they will get damaged is predictable and repairable. Thatās the basic philosophy for earthquakes.
I havenāt designed for earthquakes in so long. In MN, I once found an old manual that addresses seismic design. It literally said āthere are no earthquakes in Minnesotaā and specified a minimum bearing seat width - that is definitely the minimalistic approach. 
Oh. California also uses a lot of polystyrene on their bridges. I came to MN and started detailing with polystyrene at locations and they treated me like I was crazy, especially the way I was doing it.
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One bit of highway I used to absolutely hate driving on in CA was in Corona. A particular overpass connecting I-15 to the CA 91 freeway that was always busy. Every time I got stuck up there (usually for at least 20+ minutes during rush hour), I feared that there was going to be an earthquake and the entire thing would go crashing down. Though looking back on it now, I suppose it might be preferable to be on top of the overpass as opposed to underneath itā¦?
That one and the Terminal Island bridges in Long Beachā¦ always creeped me out a little driving on them.
Earthquakes were just a normal thing for me growing up. They never really bothered me unless I was either on top of or underneath a tall structure that started swaying. Moved to Ohio and theyāre all, āwe donāt get earthquakes here.ā Then they get a 4.1 magnitude quake and everyone freaks out, and Iām just like āLOLā¦ you call that an earthquake? Please.ā 
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Wow, thanks guys, I missed you too 
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Why is it -0? Could have been +0 if they were going to be wrong anyway
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Exactly.
20 pessimists in Helsinki
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Iām not a maths teacher but I thought zero did not and could not have a sign.
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I actually love it when this happens. If I go up, I know everything is going to be harder. If I go down, I know Iām going to have to eventually fight to get some cups back. If I stay even -
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