Use of safety intrusion alarms in work zones

After testing two models of the work zone intrusion alarm, Vermont DOT’s research unit purchased a model that uses an infrared beam sent from a transmitter unit to a receiver unit that also houses the siren. When a vehicle breaks this beam, the siren goes off. The research unit picked this model because it was the fastest and easiest to set up.

The work zone intrusion alarm’s first application in Vermont was in early 1995, when a bridge deck condition survey closed one of the bridge’s two lanes to traffic. When vehicles tripped the alarm, the siren was more than loud enough to be heard over the generator and other equipment at the work site. Since then, the research unit has used the intrusion alarm at nearly a half-dozen work zones.