Automated flagger assistance devices (AFADs) are designed to be operated remotely by a flagger positioned outside of the travel lanes and thus to reduce the flagger’s 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; 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 may 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 field studies at lane closures on two-lane, two-way roadways in Texas to assess the operational and safety effectiveness of AFADs relative to the use of flaggers. The research findings show that the violation rate for the stop-slow AFAD without a gate arm is the highest and is significantly higher than the violation rate for the red-yellow lens AFAD (which requires a gate arm). Adding a gate arm to the stop-slow AFAD decreased the violation rate such that it was not significantly different from the red-yellow lens AFAD. In addition, alternative supplemental signs increased motorists’ understanding that the stop sign would have changed to a slow sign when motorists were allowed to proceed. Overall, the research findings show that some motorists violate AFADs, especially when the queue of vehicles going in the same direction is visible to the stopped motorist.
Publisher: Transportation Research Board
Publication Date: 2013
Source URL: Link to URL
The full document can be obtained from the TRB website above.
Topics: Automated Flaggers; Flaggers; Lane Closure; Temporary Traffic Control