Flagger safety is an important issue in work zones due to the proximity of the flagger to traffic. Some strategies for improving flagger safety include slowing down approaching vehicles or removing flaggers from the immediate vicinity of traffic. The Automated Flagger Assistance Device (AFAD) is a system that can potentially accomplish both of the aforementioned strategies. In order to validate the effectiveness of AFADs in highway work zones, field testing was performed using an AFAD with a Changeable Message Sign (CMS) on a 2-lane work zone in Missouri. The field study found that AFADs helped to lower approach speeds and encouraged vehicles to stop farther behind the AFAD than a traditional flagger. In addition, a driver intercept survey found that the AFAD was viewed favorably by the general public. These field results found that AFADs are more effective than human flaggers, and drivers prefer AFADs over human flaggers.