What is this?
It is conspicuous placement, to be sure, but what does it mean? What does it signify? What is its author trying to tell us?
Personally, I think it is a bicycle seat of scorn, placed here in condemnation of all the vehicles that pass through the underpass. Its message is clear. It is saying to the city of Anchorage; “I see your motor vehicles, and your drivers too. I see the lot of you, and I do judge. I do!”
Course, then again, I am prone to flights of fancy.
northierthanthou 
Nice take on it. Alternatively the owners bike may have broken, he couldn’t carry the seat so had to cast it off somewhere and this was the first place they found.
I prefer your deeper and more meaningful version 🙂
i think of you often when engaged in discussions about religion. Hope you are well.
It wouldn’t have anything to do with a subtle message for hydrocarbon control?
My theory is that one of those high speed bikers excelerated so fast they flew off the nearby bridge and were subsequently auto-buried on impact. That’s just a peek, the rest is below ground (i.e. Bike Seat = Easter Island Head).
The reflector is facing forward, symbolizing the backwards reflection of our future. (also it’s too cheap and heavy a seat to belong to a high speed racer)