My brother claims to have had a romp on the pavement of a nearby highway that was fully paved, but not quite open. It was as clean as a highway gets.
Apparently, he was good enough to put his coat down on the ground like a gentleman.
I have no reason to doubt the story.
The Beatles "'Why Don't We Do It In The Road" comes to mind whenever either of us passes "the spot".
I think any actual spots from the incident have been washed away by now.