An alarmed, welded steel tubing security grating structure securing underground pathways from unauthorized entry:

• Optical nerve fibers are woven throughout the structure providing intrusion sensitivity.
• Detects intrusion attempts without false alarms normally associated with water flow, vibration, debris or wildlife
• Tamper resistant mounting hardware for added security
• Optional feature provides the ability to remove the grate for maintenance and cleaning (removal does cause an alarm)

Welded rebar or flat steel grating screwed to piping. Sometime alarmed with fence sensor wire.

• False alarms prevalent with water movement if alarmed.
• Maintenance and cleaning are difficult