Okay, what's up, Bank Street?

I went through downtown this afternoon on my way home from work - had some errands to run. And I don't know why I hadn't noticed it before, in the summer, say, when the pavement was still bare. But it suddenly occurred to me. The recently reconstructed part of Bank Street (which was blocked off for what felt like years) is still fairly devoid of traffic - it's my theory that people learned alternate routes while the construction was going on and haven't trickled back yet. So, it's refreshingly easy to bike along even at rush hour, except for one strange thing. All along the edge of the new pavement, through the entire rebuilt section, there's an extra layer of asphalt a bit over a foot wide, lumpy and a bit irregular, next to the curb. It looks like the layer of ice and slush that hardens at the edge of the road where the plow's blade doesn't reach, but it's permanent - there all year around.

And it forces a bike further out into the road. Not that I mind much: I should probably be further from the curb than I usually am anyway, just to ensure I have room to dodge debris and manholes. But it's strange that it's there, and it's right where you have to keep paying attention to it so as not to catch your wheel on it (and it must be mildly annoying for people trying to parallel park, too.) It's laid right down, the whole way along the street, and I have to wonder. What's it doing there? Does it have some intended purpose, or was it a mistake when they were laying the road? Seems unlikely that it was a mistake, since there's a good mile of it. It's a small, confusing little thing that didn't really occur to me until I was navigating around it tonight on my way home.