An Evaluation of Portable Traffic Signals at Work Zones

Portable traffic signal systems are now being marketed by several manufacturers. These systems have the potential for replacing flaggers in many work zones that require alternating one-way traffic control. However, because these systems are relatively new, information is needed about their effect on traffic operations and safety at work-zone locations. The Texas Transportation Institute recently conducted studies of a fixed-time portable signal system at three work-zone lane closures on two-lane, two-way highways. At each site, data were collected on traffic volumes, driver noncompliance with the signals, and vehicle stopped delay. The studies showed that a substantial savings in flagger labor costs could be achieved by using a portable fixed-time signal system with only a minimal increase in motorist delay costs. Conservative estimates of the savings at the study sites ranged from $9 to $14 per hour. The studies also suggested that the potential for vehicle accidents within the work zone may be higher with portable traffic signals because of occasional driver noncompliance with these signals. The trade-off between this possible increase in vehicular accidents and the reduction in flagger accidents could not be estimated from this research.