Presently in work zones, standard barricade warning lights are used to provide channelizing and warning functions. These yellow flashing lights are presently used for different work zone activities. Concepts for a non-standard barricade lighting system were developed and evaluated: flashing red lights when traffic is stopped or very slow within a work zone, flashing green lights when a work zone is inactive and traffic should proceed normally, expanding yellow lights when drivers should slow down and exercise enhanced caution, and sweeping yellow lights when lane closures require drivers to move to the right or left. Prototype units were designed and fabricated. A survey of driver understanding of these functions indicated that drivers would probably understand all of the functions but that the flashing red and green functions could result in conflicts with other roadway traffic control devices. A field evaluation of the expanding and sweeping functions in mock-up work zones demonstrated that driver comprehension of the lights could be translated to a driving situation. Drivers changed lanes sooner (providing a 40% longer lane change margin) in response to the sweeping function than to conventional flashing barricade lights, and subjective ratings about the intended meaning of the tested functions were also positive. (Author/publisher)
Samenvatting