GUARDRAIL ENCROACHMENT MONITOR--GEM

An experimental instrumentation system for monitoring long lengths of traffic railings to detect encroaching vehicles and measuring impact conditions has been developed and subjected to preliminary evaluation. The system makes use of the traffic railing as part of a transmission line carrying two radiofrequency waves. The radiofrequency energy reflected from vehicles entering the electromagnetic field about the line is detected and used to determine vehicular speed, direction, angle, location, path and size. A solid-state, digital data acquisition system is triggered by a detected encroachment to record pertinent data. Capability to record data on up to 50 encroachments is available. Computer data processing generates plots of vehicle path and tabulates data on time, speed, angle, location of encroachment, vehicle size and nature of encroachment. The system is packaged to be suited for unattended roadside installation and will operate continuously from a self-contained 12 V battery for periods of up to 10 days without servicing.

• Supplemental Notes:
  • See also PB81-235160.
• Corporate Authors:

  Southwest Research Institute

  6220 Culebra Road, P.O. Drawer 28510
  San Antonio, TX  United States  78228-0510

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • King, J D
  • CERWIN, S A
• Publication Date: 1981-5

Media Info

• Pagination: 152 p.

Subject/Index Terms

• TRT Terms: Barriers (Roads); Data collection; Data recorders; Detectors; Electromagnetic wave propagation; Electromagnetic waves; Highways; Impacts; Measuring instruments; Pulses; Radio frequency
• Uncontrolled Terms: Barriers
• Old TRIS Terms: Radiofrequency pulses
• Subject Areas: Data and Information Technology; Highways;

Filing Info

• Accession Number: 00344406
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: FHWA/RD-80/175, SwRI15-4017
• Contract Numbers: DOT-FH-11-8498
• Files: NTIS, USDOT
• Created Date: Nov 23 2003 12:00AM