I manage a property on the corner where a motorcyclist died earlier this year.
The by-laws surrounding the impromptu shrines aren't defined in most jurisdictions.
In some they're clearly given ninety days. Not here.
The politics and ethics of it all are up for grabs.
There was a lot of activity on the corner for about two weeks.
I'd removed dead flowers three times over the next ~10 weeks before they stopped being replaced.
The pillows?, panties? tomato plant?, stuffed toys and other weird stuff came and went or I tossed them in the bin.
There's a surviving part of a busted Buddha figurine, a Xmas mug, and faded messages left.
The welded cross of a combination and adjustable wrench is nice, discrete, long lasting and secure.
His helmet, found about 15' further west, is also part of the memorial.
Those will probably be removed when the city repaints the post. It's a new post but could get taken out by an errant scud tomorrow.
Guy bled out on the grass about twenty feet past the parking regulations sign he hit airborne after broad siding a left turning car)
Had the sign not been there he'd have probably landed in my holly tree and survived.

Personally, I doubt the killer driver ever came to visit the site.
It's so much watered down from its roots in the Provo White Victim Plan: The Plan proposed that anyone having caused death while driving would have to build a warning memorial – memento mori – on the site of the traffic collision by carving the victim's outline one inch deep into the pavement and filling it with white mortar