A fully interactive PC-based STISIM driving simulator was used to test the effectiveness of Intelligent Lane Control Signals (ILCS). The participants were 160 licensed drivers from four age groups: 18-24, 32-47, 55-65, and 70+ years of age. Each participant drove three times in a counterbalanced order. In each trial, after driving five miles in the center lane of a six-lane highway where the speed limit was 65 mph, they encountered five sets of ILCSs that occurred at half-mile intervals. These ILCSs presented (1) 45-mph speed limit messages; (2) 35-mph speed limit messages; (3) a yellow lane closure warning; (4) one of three merge messages that used a diagonal arrow, or words, or dynamic chevrons to indicate that drivers should move from the center lane; (5) a red lane closure warning.
Analysis of lane position data showed that the diagonal arrow merge sign was the most effective; participants moved from the center lane 266 feet before reaching the diagonal arrow merge sign, 123 feet before reaching the dynamic arrow merge sign, and 54 feet before the merge sign with words.
Analysis of driving speed data indicated that the speed limit signs were effective. Before the 45-mile speed limit was visible, participants drove at 63 mph. When the 45-mph speed limit was visible, they reduced speed by approximately 10 mph. Then on the approach to the 35-mph speed limit, they reduced speed by a further 14 mph on average, they were driving at 38.7 mph shortly after passing the 35-mph speed limit.