n. A glass-enclosed pedestrian overpass connecting two buildings.
2001
A curved sky bridge will connect the two buildings and the 15-level parking garage that is under construction at the corner of Bell and Smith. From above, the sky bridge will look like a ring around Saturn. The designers were hoping the circular tube would create something more than than "just another gerbil tube" between towers, Jones said.
1988 (earliest)
"Gerbil tubes" is the term used by one mayor I know to describe these glass bridges. Another acquaintance has coined an even more vivid phrase for all such walkway systems. He speaks of "the condomization of the American city." Like sperm cells who mustn't be allowed either to spread disease on the one hand nor generate life on the other, the pedestrians in the glass tubes are isolated from the world around them.