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.