My Boston> Keep back 300 feet
I'm not great at math, but I think that's about the length of a football field.
That can be between two to four blocks, depending where in the city I happen to be.
Tim McCormack@my_roxbury Right? Who do they think they're fooling?
EDIT: It's a good idea to keep pretty far back of dump trucks carrying gravel, though. But even then... not 300 feet.