Oyster™ Self-Rising Flood Barrier
Oyster™ Self-Rising Mechanical Flood Gate
Automatic ramp flood protection for garages, driveways, loading docks, transit entrances and more.
The Garrison Oyster™ Self-Rising Mechanical Flood Gate is a hydrodynamic, water-activated flood barrier designed to protect any downward-sloping entrance — including parking garage ramps, driveway ramps, transit and subway station openings, loading docks, tunnels, and other below-grade access points.
In normal conditions, Oyster lies flat on the ramp so vehicles and pedestrians can pass freely. When floodwater approaches, it flows into the barrier’s internal cavities and uses its own buoyancy to automatically lift the panel into a vertical flood wall — without power, motors, or human intervention. This passive flood gate system resets to the closed position when floodwaters subside.
Up to 48” of Protection Height
Full Ramp and Opening Protection
Self-Deploys without power
Protect What Matters Most
Oyster™ combines hydrodynamic engineering with passive mechanical design to safeguard critical ramped and below-grade access points. Lying discreetly within the surface during everyday use, the barrier automatically rises as floodwater enters its internal chambers transforming into a vertical flood wall powered entirely by buoyancy. With no reliance on electricity or human intervention, Oyster™ ensures continuous protection for parking structures, transit systems, loading docks, and other high-risk openings in severe weather conditions.
Application
Designed for high-risk ramps & openings
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Parking garage entrances and exits
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Driveway ramps to underground parking or back-of-house service areas
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Transit systems and subway station openings
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Loading dock ramps and service tunnels
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Stadiums, arenas, malls, convention centers, hospitals, universities and data centers
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Any site where water runs down a ramp toward critical below-grade areas
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Fully automatic operation (no power required)
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Hydrodynamic system rises using the ballast of floodwater; no power, pumps, motors, or staff deployment required. Oyster is a fully passive flood barrier.
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Drive-through safe
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Four-layer, heavy-duty panel structure supports vehicle loads; cars and light trucks can pass over the closed barrier and, if necessary, safely drive out over the ramp even when the barrier is raised (within design limits).
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Flat, low-profile when not deployed
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Panels are installed in-ground or laid on top of concrete with a ramped thickness of only 2.0”–3.9”.
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Modular and adaptable
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Standard 23.6” wide flood gate modules. Non-standard “filler” units come in 6.3”, 11.4”, 13.2” and 18.5” wide sections, allowing the system to match almost any ramp or opening width with a clean fit.
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Durable
Built using durable materials, hardware and construction for long life.
Performance Advantages
Automatically Rises
Passive flood gate rises automatically using hydrostatic pressure. No electricity or battery power needed.
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Flexible side sealing system
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Adjustable side seals and optional Z-profile gap fillers handle variations in wall alignment and allow installation where the distance from barrier to wall ranges roughly 2.0”–5.9” depending on height.
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In-ground or surface-mounted versions
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Choose a recessed embedded frame for new construction or a surface-mounted frame for retrofit projects when the slab cannot be cut. Both are based on the same core barrier modules.
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Low maintenance, long life
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Constructed from aluminum, aluminum castings, 316L stainless steel and nodular cast iron, with EPDM/silicone rubber sealing elements
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Proven performance
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Proven performance at hundreds of installations globally, this passing flood gate system continues to perform time and time again.
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3 Heights
Available in 24”, 36” and 48” heights, depending on your protection needs.
How the Oyster™ Automatic Flood Gate Works?
The Oyster flood gate uses a passive hydrodynamic mechanism in each module to sense rising water and lift the panel, creating a flood wall against incoming water.
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Standby (Dry Conditions)
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Vehicles and pedestrians pass normally over the anti-skid driving surface. Flood panels sit flush with concrete or lay just on top of the surface.
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Rising Water & Activation
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Floodwater approaching the flood barrier flows through inlets into internal water-storage cavities inside each module.
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Buoyancy acts on internal floatation plates, which in turn push the rotating flood panel upward.
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Automatic Deployment
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As water depth reaches the design threshold, flood barrier modules rise into the raised position and lock into a near-vertical position.
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Continuous ramp seals and side-wall flexible seals create a tight seal, blocking water from entering the protected opening.
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Oyster is a fully passive flood protection system, requiring no human intervention.
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Controlled Drainage and False Deployment Prevention
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Integrated drainage and water outlet controls allow small amounts of water to drain away, preventing nuisance deployment from shallow ponding. Only when inlet flow exceeds drainage capacity does the barrier rise.
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After the Flood
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Once the event ends, water drains from the cavities.
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Operators follow a simple procedure to lower the panel back to its flat position and visually confirm seals and hardware for future use.
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Oyster™ Barrier Closed Position
Oyster™ Flood Gate Open Position - Dry Side
Oyster™ Automatic Flood Gate Open Position - Water Side
Oyster™ Resources and Guide
Feel free to contact us with any questions or for advice on the best flood barriers, flood gates and flood control solutions for your specific need.