With the first satellite launch in the late 70s, the U.S. global positioning system (GPS) expanded our technological boundaries. Today’s global navigation satellite systems (GNSS) include GPS and newer, similar systems that transmit location and time information from satellites in space to receivers on Earth.

This technology can help protect workers across many industries, including farming, construction, mining, and logging. Each industry, however, presents unique challenges to the safe use of GNSS. For example, trees and other land features, or topography, on logging sites potentially can interfere with satellite signals, and lack of cellular or WIFI networks often hampers our ability to share data in remote areas.

At the University of Idaho, National Institute for Occupational Safety and Health (NIOSH)-funded investigators explore the effects of interferences on the accuracy of alerts triggered by GNSS-based geofences. The investigators tested geofence alerts across different types of forest conditions in the University of Idaho’s experimental forest. In their studypublished in the journal PLOS One, the researchers reported that alert accuracy or missed signals varied depending upon tree density and other aspects of topography, such as the proximity of hills, valleys streams, and roads. Since these factors differ significantly on actual logging worksites—sometimes even within one worksite—these results indicate that GNSS technology can help improve communication and general situational awareness at the worksite. However, due to the occurrence of inaccurate alerts or missed signals, the investigators cautioned against relying upon geofences that define safe work zones.

These findings confirm two previous studies by the same team, showing that a mobile geofence could help increase workers’ situational awareness of their worksite in logging and other occupations. Together, findings from all three studies highlight the importance of further research to improve the accuracy of GNSS alerts across different types of forest terrain and for different workplace hazard scenarios that occur in forestry.

The NIOSH Expanding Research Partnerships Webinar Series will feature this research during its May 2018 presentations.

More information is available:

• Real-time Positioning in Logging: Effects of Forest Stand Characteristics, Topography, and Line-of-Sight Obstructions on GNSS-RF Transponder Accuracy and Radio Signal Propagation
• Characterizing Rigging Crew Proximity to Hazards on Cable Logging Operations Using GNSS-RF: Effect of GNSS Positioning Error on Worker Safety Status
• Hazards in Motion: Development of Mobile Geofences for Use in Logging Safety
• NIOSH Research Rounds: Mobile Geofence Can Help Monitor Work Surroundings
• NIOSH: Extramural Research and Training Programs­
• University of Idaho Experimental Forest