This viaduct has always been very interesting to me. US 6 actually runs on the lower portion, and has since it was rerouted onto Vasquez Boulevard, which was well before the freeway was built. I have a pic of the US 6 reassurance shield from below the deck somewhere, but even Google Maps shows this if you zoom in.
Got an exact location? There's a sign on northbound Steele showing that US 6 hops on I-70 there: http://usends.com/Explore/US87inCO/index.html
No! And now that I'm looking at it again, Google Maps and me are wrong. I mean, I guess it's a bit of a stretch to imagine US 6 exiting from I-70 at Brighton Boulevard, making a left, then a hard right, then following that lower deck, but that would so cool.
I did find my picture of that sign, but mine is from the westbound ramp to Brighton Boulevard. I had always assumed it was just a preliminary marker, since 6 was to join at the next ramp. The set of pictures I wanted were conveniently archived on a different computer that is not hooked up. So, instead of actually hooking it up, this sent me on a whirlwind of research, and I discovered Colorado's OTIS, which has just rocked my world. But that basically says about CODOT's dealing with federal highway-interstate multiplexes just as that link does: they don't exist. 006G ends at I-25, and 006H begins on the ramp to Steele. I looked at some older maps I had, but they weren't detailed or old enough, but I found a
1962 Denver map on eBay that shows 46th Avenue connecting directly to an early version of the Mousetrap.
Interesting stuff, so I'm glad I was pointed to actually looking this up.
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I should add that you can tell that I-70/US 85/US 6 marker that's pictured on that site is above Brighton Boulevard as it's right next to the 275 mm sign, which is Brighton Boulevard. Steele is at 276.