Twenty seconds, according to Theresa Cristy who studies “elevatoring” for the Otis Elevator Company. Christy was interviewed in this story by Kai Ryssdal on Marketplace yesterday.
"Yeah, there is a magic number, and it's 20 seconds," she says, "and that's a number that's been used for over 50 years in the industry."
But wait, its 20 seconds in office buildings but its a little bit longer in residential buildings. She didn't say how much longer.
Of course twenty seconds waiting for an elevator is nothing compared with being stuck inside one for forty one hours!
Also interesting to note is that the local offices of the International Union of Elevator Constructors are housed in a single story building in Columbia Gateway.