VIXA GateShield AI is an autonomous flood traffic control agent protecting drivers from fatal inundation at tunnel, bridge, and underpass entrances. Climate-driven flash floods create severe blind-spot hazards where drivers enter submerged tunnels or compromised bridges unaware. Legacy responses lose critical golden time through manual operator verification, reporting, field dispatch, and physical closure, while point-level water gauges fail to show area-wide inundation spread. GateShield closes this detection-to-action gap by combining AI vision, hydrological sensors, and automated barrier control on local edge NPU hardware. A dual-engine architecture decouples action from reasoning: a lightweight edge vision model triggers physical barrier closure and variable message sign (VMS) entrance alerts in sub-seconds via preapproved safety rules, while an on-device Vision-Language-Action (VLA) model simultaneously converts visual and hydrological telemetry into real-time situation briefings and dashboard notifications. GateShield eliminates manual dispatch delays, securing life safety while preserving full operator override.