A google search for “street sweeper metal strips” comes up with lots of info. Looks like they are indeed just that.
But I must say, in all my years of walking the streets (pun not intended) I never saw anything like these. Perhaps the sweepers in my area use a different method. In fact, my guess would be that those metal strips used in a sweeper would be very abrasive to the road surface.
(text that accompanied photo)
These are the bristles which have fallen off street cleaning machines. I’ve foraged these from various roadways along the West Coast- Los Angeles, San Francisco, Seattle, Portland… now I have included some from our recent trips to Iceland and British Columbia (who knew they’d look the same, all over the world?)