The Pittsburgh Post-Gazette's Steve Twedt reports that David G. Dye, Acting Assistant Secretary of the Mine Safety and Health Administration, says initial tests of a new wireless two-way communication system for underground mines have "shown promising results."

One prototype system, made by Kutta Consulting, uses medium frequency radio signals relayed through the mine's metal infrastructure to send a signal more than two miles underground. TeleMag, made by TransTek, was the only system to transmit a voice signal through the earth at 270 feet.

"We are hopeful that the systems being tested will provide long-sought solutions to the daunting challenge of communicating miles into the earth to help miners safely evacuate during an emergency," Dye says.

On Wednesday, Congress approved the Miner Act, which requires underground mines to have two-way wireless communication within three years.