sidewalk superintendent

sidewalk superintendent (plural sidewalk superintendents)

1. (construction) A passer-by or other person who watches and possibly advises work at a construction project from a sidewalk or other vantage point.
   • 1962 January 14, “Builder to Start on the Top Floor”, in The New York Times‎, →ISSN:

     Even the most occasional sidewalk superintendent knows that in the construction of a tall building the first floor is put in before the second, the second before the third, and so on.

• kibitzer