The University of Minnesota's Department of Mechanical Engineering tested several interfaces for relaying work zone messages to drivers including a roadside, portable changeable message sign, a smartphone presenting only auditory messages, and a smartphone presenting audio-visual messages.
A driving simulation study was conducted that tested 97 drivers in two different types of work zones. Participants drove through these work zones three times, with a different messaging interface each time to communicate hazardous events to the driver. The interfaces included a roadside portable changeable message sign, a smartphone presenting only auditory messages, and a smartphone presenting audio-visual messages.
- There was better driving performance on key metrics including speed deviation and lane deviation for both in-vehicle message conditions relative to the roadside signs
- Drivers reported significantly less mental workload, better usability, and greater work zone event recall for both in-vehicle conditions relative to the roadside sign condition.
- For eye-tracking, drivers took their gaze off the road less often for the in-vehicle messaging conditions, as drivers had to look over to read the roadside signs to understand the messages.
- The positive effects of in-vehicle messaging appeared to be elevated for the more difficult lane closure route in the driving performance data, suggesting that in-vehicle messages were helpful for more challenging roadway conditions.
- If the in-vehicle messages are delivered in a controlled and driving-relevant manner, there appeared to be no effect of distraction and driving performance was improved
- Placement of the smartphone did not appear to be a significant factor for driving performance when there was an auditory component for the messages.
- The researchers recommend field testing in-vehicle message systems and exploring possible avenues of broad implementation.