Bluetooth technology may soon alert drivers to highway work zones

work zone traffic sign
Bluetooth tags can be easily attached to traffic signs and other objects in
and around highway work zones.

For several years, U of M researchers have been teaming up on an interdisciplinary effort to develop a Bluetooth-based system that can be placed in work zones to deliver warning messages to drivers. In a new project, field tests show that the system is capable of providing dynamic, location-based in-vehicle messages for motorists approaching a work zone.

“Providing drivers with tailored in-vehicle messages before they arrive at highway work zones has the potential to save lives and prevent many injuries,” says Chen-Fu Liao, a senior research associate with the Department of Mechanical Engineering. “In recent years, the challenges of work-zone safety and mobility have been exacerbated by the growing issue of distracted driving. Our research uses in-vehicle spoken messages to calibrate drivers’ understanding of the work zone and reduce risky behavior associated with distraction.”

The latest research takes the previously designed prototype system—which uses inexpensive Bluetooth tags placed in work zones to deliver non-distracting audio alert messages through a smartphone or vehicle infotainment system—and tests it in real-world situations.

The objective was to refine the previously developed in-vehicle message system to incorporate a sustainable power source design, implement results from earlier human factors studies to provide work-zone information to motorists, and evaluate the system’s performance. “We believe this approach could provide an alternative to automatic speed enforcement for changing driver behavior in work zones by providing dynamic and timely work zone information such as awareness of workers on-site, changing traffic conditions, or hazards in the environment,” Liao says.

To field test the work-zone warning system, researchers deployed several Bluetooth tags at three work zones in the Twin Cities metropolitan area. With the previously developed app, called WorkzoneAlert, running in the background on a smartphone, the research team drove a sedan and a minivan through each of the three work zones at different times of the day to evaluate the system’s performance under different traffic conditions. Bluetooth detection rate, range, and available reaction time were used as performance measures for system evaluation, and vehicle location and timing of each triggered message were logged for data analysis.

Results of the field test show that the WorkzoneAlert app is able to reliably detect the Bluetooth tag placed an average of 127 meters away on traffic signs or portable radar speed signs. In addition, researchers found the system was able to successfully announce the corresponding message associated with each Bluetooth beacon. At a posted work-zone speed limit of 35 to 45 mph, the system allowed five to nine seconds of reaction time prior to the motorists approaching the location where the beacons were installed.

In the future, researchers expect to use the results from this study to prepare for a field operational test to continue evaluating the system.

The project was sponsored by the Roadway Safety Institute.


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Michael McCarthy