The birth of the underground city
Life 20 feet below the street
Engineering and architectural design
The great flood of Tropical Storm Allison
Who invented the passive, automatic flood barriers installed in the Houston tunnels after the 2001 flood?
misslily Houston Downtown Tunnels
Bayou broke right through / Tunnels down below / Six miles of rivers underground

misslily The flood completely submerged the tunnels, causing tens of millions of dollars in damages.
What is a major advantage of 'passive' flood barriers over 'active' electric flood gates?
What nearby body of water overflowed and poured into the Houston tunnels during the 2001 flood?
Buoyant defense: Houston's passive flood gates require absolutely no electricity, lifting automatically using the physical buoyancy of rising water.

misslily Houston engineer Lou Waters invented automatic, power-free flood barriers to seal the tunnels.
How high did the water level get inside some of the flooded medical and downtown basements during Tropical Storm Allison?
Which major hurricane in 2017 tested the newly installed flood barriers in the Houston tunnels?
An overflowing of water onto land that is normally dry. In June 2001, Allison's torrential rainfall completely submerged Houston's downtown underground pedestrian network.
