AMARILLO, TEXAS – The Amarillo Police Department recently installed new siren devices on some of its patrol vehicles. Rumblers, as they are called, give off a low-pitch sound wave that will vibrate the ground, alerting other motorists of an emergency vehicle’s presence, according to the Web site

A subwoofer speaker is installed in the front wheel wells, and the sound projects out in front and to the side of the cars. Officers can initiate the Rumbler by bumping the steering wheel. A vibration blast lasts about 10 seconds.

Video Rumblers are on 15 police cars now, but the department plans to install another 30 this year. The department hopes to put the devices on its remaining 30 vehicles after that as its budget allows.

The device is manufactured by Federal Signal Corp., an emergency products company based in University Park, Ill. Each costs $400 and is paid for from the general police budget. Police began researching the technology after an accident three years ago involving a squad car and a civilian vehicle.

Rumblers can work with a patrol car’s existing siren equipment. The device takes about three hours to install.

Officers sitting in their vehicles are largely unaffected by the Rumbler because the sound travels away from the steering column.