Work zones present an increased risk to drivers and the work crew. To mitigate these risks and lower the rate of crashes in work zones, this study investigated the potential advantages and disadvantages of in-vehicle messages to communicate work zone events to the driver. A potential positive outcome would be that drivers would be more aware of any risky work zone events and drive appropriately due to the immediacy of the in-vehicle messaging system. The potential downside would be the risk of driver distraction, as numerous cellphone studies have demonstrated the hazards of having communication technology in the automobile. To investigate these possibilities, multiple literature reviews were conducted to illustrate the crash risks imposed by work zones and what factors exacerbate these risks, along with the ideal design guidelines for any in-vehicle messaging system. A work zone safety survey was conducted to uncover driver attitudes in Minnesota toward work zone safety. The survey also explored driver attitudes toward smartphones, smartphone use, and the potential application of in-vehicle messages through smartphones. The survey found that a significant number of drivers make use of smartphones in the automobile and that they place these smartphones in various locations throughout the vehicle with little commonality between respondents. Furthermore, the survey found that a subset of Minnesota drivers was skeptical of the validity of the warnings on roadside signs for work zones and were receptive to using electronic messaging systems. However, the possible issue of safety when driving with an invehicle system was identified by participants, indicating that empirical studies like this one were valuable. Researchers at the HumanFIRST laboratory followed the survey with the design of the in-vehicle messages and the design of the simulated driving study to test the efficacy of the messaging system on driving safety. The simulated driving study tested drivers in two different types of work zones, a shoulder work route and a lane closure route. Participants drove through these work zones three times, each with different work zone events and messaging interfaces to communicate the hazardous events to the driver. These message interfaces included a roadside, portable changeable message sign (PCMS), a smartphone presenting only auditory messages, and a smartphone presenting audio-visual messages. Events in the work zone were typical, including slowed traffic, lane closure, heavy machinery, workers ahead, among others. The in-vehicle messaging smartphone was either mounted on the dashboard or placed in the passenger seat. During the drives, researchers recorded objective measures of driving performance subjective or reported variables such as event recall, mental workload, user-friendliness, and eye-tracking metrics. The data analysis of the driving simulation study found that 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. Furthermore, 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. Finally, 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. The conclusions are twofold. First, if the in-vehicle messages are delivered in a controlled and drivingrelevant manner, there appeared to be no effect of distraction and driving performance was improved. Second, 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 invehicle message systems and exploring possible avenues of broad implementation. (Author/publisher)
Abstract