Passive Underground Flood Protection

A system for restricting water flow in a surface vent, the system comprising:

• a frame having a water ingress end and a water egress end, the frame configured to receive water from a surface via the water ingress end;
• a door coupled to an interior portion of the frame, the door configured to transition between an open orientation and a closed orientation;
• and
• one or more reservoirs coupled to the door, each reservoir configured to collect at least a portion of the received water and further configured to cause the door to transition between the open orientation and the closed orientation based on a weight of the collected water in the one or more reservoirs;
• wherein the open orientation allows the received water to exit the water egress end, allows air from below the frame to exit to a surface via the water ingress end, and allows air from above the surface to enter the water ingress end;
• and
• wherein the closed orientation at least partially restricts the received water from exiting the water egress end, at least partially restricts the air from below the frame from exiting to the surface via the water ingress end, and at least partially restricts the air from above the surface from exiting the frame via the water egress end.

A system for restricting water flow into a subway vent, the system comprising:

• a grating disposed in a paved transportation surface;
• a frame disposed beneath the paved transportation surface, the frame configured to receive water from the paved transportation surface through the grating;
• and
• a closure door coupled to an interior portion of the frame, the closure door configured to allow water to exit the frame while the closure door has a first center of gravity, and further configured to restrict the water to exit the frame while the closure door has a second center of gravity;
• a frame weep hole in the frame, the frame weep hole configured to allow at least a portion of the received water to exit the frame at a first flow rate;
• and
• wherein the closure door transitions between the first center of gravity and the second center of gravity based on the weight of the water.