Motorists' Understanding of Automated Flagger Assistance Devices in Work Zones

Automated flagger assistance devices (AFADs) are designed to be operated remotely by a flagger positioned outside the travel lanes and thus to reduce their exposure to vehicular traffic. There are two types of AFADs: one type uses a remote-controlled stop and slow sign to alternate the right-of-way and the other uses remote-controlled red and yellow lenses to alternate the right-of-way. A gate arm is required only with the latter. Although AFADs may have increased the safety of flaggers, there were concerns that motorists might have misunderstood AFADs and proceeded before it had been safe to do so. As part of a recent Texas Department of Transportation project, Texas A&M Transportation Institute researchers conducted surveys to assess motorists' understanding of both types of AFADs. For the stop–slow AFAD, a newly designed “Wait on Stop–Go on Slow” symbol sign resulted in the highest percentage of participants who understood that they should stop and remain stopped until the AFAD indicated that it was safe to proceed. However, for all of the stop–slow AFAD treatments, a portion of the participants indicated that they would have stopped and then proceeded instead of waiting until the AFAD displayed the slow sign. Thus researchers recommend that a gate arm be required with stop–slow AFADs. For the red–yellow lens AFAD, participants understood the stop phase. However, there was evidence of a lack of understanding of the difference between the proceed and transition phases. Even so, the use of the gate arm appeared to inform motorists when to proceed and when to stop.