Driver Understanding of Work-Zone Flagger Signals

The results of a human-factors laboratory study conducted in Texas to evaluate driver understanding of 13 work-zone flagger signals are reported. This was an exploratory study in which 123 motorists participated and 23-73 motorists viewed each signal. The signals evaluated included (a) seven standard signals recommended in the 1978 national Manual on Uniform Traffic Control Devices (MUTCD), (b) two signals recommended in the 1973 Texas MUTCD but not included in the 1978 national MUTCD, (c) two signals recommended for use by police, and (d) two nonstandard signals that combined standard signals from the 1978 national MUTCD. A STOP or SLOW sign paddle, a red flag, and/or hand motions were used to perform the various signals. The results indicated that (a) most drivers understood all seven of the 1978 MUTCD signals except signal 2 (Stop Traffic) and signal 9 (Alert Traffic) ( both signals required the use of a flag alone), (b) exclusion of the two signals in the 1973 Texas MUTCD from the current Manual was in the best interest of work-zone safety, (c) the two police signals were understood by most drivers but are not recommended for use at this time, and (d) the two nonstandard signals showed no advantage over the 1978 MUTCD signals. The study indicated that most of the signals that involved the use of a STOP-SLOW sign paddle and/or hand motion were understood by the drivers but the signals in which a flag alone was used were less effective.