SUMMARY OF COMPARISON OF LIFE-DETECTION INSTRUMENTATION
In August 1989, the U. S. Department of Labor Mine Safety and Health Administration, in cooperation with Johns Hopkins University at the Francis Scott Key Medical Center, conducted a collapsed building exercise during which eight seismic and acoustic life-detection systems were used and compared. The staffs of the Pittsburgh Health Technology Center and Westinghousc Mine Emergency Operations also participated in the exercise. Following is a summary of the recommendations and conclusions resulting from that event.
THE EXERCISE
Primary objectives: To characterize and compare several seismic and acoustic systems used to detect trapped persons in building-collapse situations and to determine the applicability of the systems for emergency mine operations. This exercise was the first attempt at identifying a significant area of research required for the improvement of urban search and rescue capabilities.
Site: Demolition of the Community Services Center building at the Francis Scott Key Medical Center in Baltimore, Maryland. The 10-story, steel-frame structure was built in 1931. The center’s overall dimensions were about 200 feet by 80 feet, and it had concrete floor slabs and brick and terra-cotta cladding.
Systems tested: The Mine Safety and Health Administration (MSHA) Seismic Location System (USA), two MSHA Mini-Seismic Detection systems, the TPL-310 (Israel), the Wandel and Goltermann Life Detector (West Germany), the Astro-Med Dash II (USA), the Military AN/PSR1A (USA), the Vibraphone ASB-6 (France), and the Copp Life Locator (USA).
Systems selected for this test either were already in the possession of the MSHA Mine Emergency Operation (MEO) team or volunteered for the exercise.
Testing conditions and limitations: Systems were tested side by side during the exercise. Tests were limited by several operational constraints. Because test-site conditions varied, there were differences in instrument-measurement methodologies and operator proficiency. Also, the interpretation of certain data was subjective (hard copy not available), and accurate comparisons of the systems’ sensitivities could not be performed.
CONCLUSIONS
In general, systems employing seismic (relating to vibrations propagated through the rubble) sensors performed better than systems employing only acoustic (relating to vibrations propagated through the air) sensors.
There was less subjectivity inter preting data from instruments producing hard copy and/or visual indications of the received signal.
Detectability is a direct function of the homogeneity of the rubble and the presence and location of voids.
The operator’s training and familiarization with the equipment are extremely important in ensuring that life-detection instrumentation is used properly and most effectively.
Signals generated on the rubble pile may have different transmission properties than signals generated from within the collapsed structure, and such differences may affect detection capabilities.
Systems equipped with both seismic and acoustic sensors should be utilized for mine emergency operations and urban search and rescue, since each responds differently to signals of vary ing frequency content. Signals having certain dominant frequency characteristics are generated by different sources (iron bar, wood block, etc.). Search and rescue personnel should be sure to cover the widest frequency spectrum possible when using life-detection systems while simultaneously monitoring selected frequencies that have proved useful based on experience.
RECOMMENDATIONS FOR URBAN SEARCH AND RESCUE
- A uniform set of definitions for search and rescue (seismic, acoustic, etc.) should be developed.
- Urban search and rescue equipment should have the capacity for hard copy output so that comparisons of various systems can be conducted on a quantitative basis.
- Urban search and rescue equipment should have both seismic and acoustic detection capabilities.
- Operators of search and rescue equipment should have sufficient manufacturer or vendor training so that they can be certified to operate the particular instrument in use.
- A National Signaling Code similar to that used by the MSHA to locate trapped miners should be developed.
- Integrated urban search and rescue exercises that combine management systems, electronic-detection systems, and dog teams should be conducted on a regular basis throughout the United States; sites should present a variety of conditions and rubble compositions
