Propagation measurements before, during, and after the collapse of three large public buildings

NIST is investigating radio communications problems faced by emergency responders (e.g., firefighters and police) in disaster situations such as collapsed buildings. A fundamental challenge to communication into and out of large buildings is the strong attenuation of radio signals caused by losses and scattering in the building materials and structures, and the problem is amplified in a collapsed building. We are investigating various schemes for detecting emergency responders and civilians with portable radios or cell phones who may be trapped in voids in a collapsed or partially collapsed building. The first part of this effort is to understand radio propagation in collapsed structures. Buildings scheduled for implosion provide the ideal research environment for investigating radiowave propagation issues in fully or partially collapsed structures. The experiments reported here were performed before, during, and after the implosion of three large building structures. They consisted of measurements of the attenuation of radio signals caused by the building materials and structural components. Measurements were performed at various frequencies of interest to emergency responders, namely frequencies near the public-safety and cell-phone bands (approximately 50 MHz, 150 MHz, 225 MHz, 450 MHz, 900 MHz, and 1.8 GHz).