Work Zone Intrusion Alarm Effectiveness

The New Jersey Department of Transportation (NJDOT) commissioned a study to evaluate how effective a work zone safety device known as the “SonoBlaster! ® Work Zone Intrusion Alarm” would be in protecting maintenance workers from injury caused by vehicles that breach the work zone, and how well it would be accepted by workers. The device is mounted on a traffic cone and when impacted by a vehicle, emits an alarm that provides advance warning to allow workers to react to avoid the intruding vehicle. The device also alerts the driver who may be drowsy or distracted, who can respond by braking or steering out of the work zone, or both actions.

In a pilot test of the device, SonoBlaster! ®-equipped traffic cones were used with standard cones to close a lane of traffic for maintenance work. Two impact simulations were performed resulting in sounding of the alarm, as no impacts occurred from traveling vehicles. The alarm’s sound volume and duration were satisfactory during normal traffic conditions for distances of at least 200 ft, including when ear protection was worn, but no conclusion could be made about hearing the alarm during jack hammer operations. Employees indicated that several set-up procedures were difficult. Moreover, in multiple instances the alarm fired when the control knob was in the locked, unarmed position. Additional field trials could not be scheduled. However, NJDOT believes that problems with quality control and reliability, combined with the cost of the alarm, raise doubts about the desirability of and benefits to be gained from deploying the device on NJDOT maintenance jobs.