In-vehicle work zone messages prove to be more effective than portable roadside dynamic message signs.
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.
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United States

In-Vehicle Work Zone Messages


Work zones present an increased risk to drivers and the work crew. To mitigate these risks, this study investigated the potential effects of in-vehicle messages to communicate work zone events to the driver. The researchers conducted a work zone safety survey for Minnesota drivers which found that a significant number of drivers make use of smartphones in the automobile, and place these smartphones in various locations within the vehicle.

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.

Lessons Learned

  • 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.

In-Vehicle Work Zone Messages

In-Vehicle Work Zone Messages
Publication Sort Date
Morris, Nichole L.
Minnesota DOT

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