Overall, 44 participants were recruited to complete 12 simulated driving tasks in a high-fidelity driving simulator. Of particular interest to the investigators were sign content, frame refresh rate, and sign placement of driver speed reduction. In addition to the simulator test, a small-scale field testing was also conducted.
Sign frame refresh rate was found to have a significant effect on drivers' initial speed and speed reduction. Participants had longer fixation on the DMS when worker presence was mentioned in the sign content. Findings from the field study suggested DMS is most effective at night. Sign content and placement had no effect on speed reduction and compliance.
The results of this study yield the following recommendations:
- Use dynamic message signs if work will be conducted at night. The presence of the DMS is more effective than static signs at reducing driver speed in the overnight hours. The presence of the sign is not detrimental at other times, but is truly beneficial when it is dark on the roadway.
- Use a longer refresh rate between messages on the dynamic message sign. This allows drivers time to read and interpret the information displayed on each screen.
- If workers will be present in a work zone, mention their presence on the dynamic sign. This heightens the awareness of the driver as they approach the work zone.
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