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
• Optional cage design provides alarmed detection on the sidewalls of the pipe.
• 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. Sometimes alarmed with fence sensor wire or similar technologies.

• False alarms prevalent with water movement.
• The pipe sidewalls remain vulnerable and are not alarmed
• Maintenance and cleaning are difficult