Logging consistently ranks among the most dangerous occupations [1
]. With a rate of 136 fatal injuries per 100,000 workers (91 fatalities total) in 2016, logging workers had by far the highest fatal injury rate in the United States [3
]. Human factors, or “environmental, organizational and job factors, and human and individual characteristics which influence behavior at work in a way which can affect health and safety,” are among the variables contributing to hazardous working conditions on logging operations [4
]. For example, Slappendel et al. identified factors contributing to logging injuries from the literature published from 1970–1991, which they organized into four categories: (1) personal characteristics (judgement and decision making; skill and technique; experience, education, and training; and age); (2) machinery, tools, and equipment (chain saw vibration and noise, chain saw kick back, forest machine design, protective equipment, and maintenance); (3) work organization (task demands, mechanization, piecework vs. salary payment, contracting/subcontracting, and company size); and (4) physical environment (climate, lighting, terrain, and flora) [5
]. Fatigue related to long shifts, reduced sleep, and fast-paced, intensive work can also be a factor in logging injuries [6
], along with financial pressures and inadequate training [8
Improvements in basic safety measures in the US logging industry, such as use of personal protective equipment (PPE), have been made in part due to workers’ compensation insurance requirements [9
]. Mechanization has helped reduce fatalities and near-fatal injuries by moving more workers into enclosed, protected machine cabs in ground-based logging systems, which operate on moderately sloped topography [10
]. While the logging industry has experienced a trend of fewer injuries with greater mechanization, the severity of injuries has increased [9
]. Emerging mechanized equipment for steep-slope harvesting is growing in use [12
] but has not been widely adopted in the US Inland Northwest where exposed ground workers are still common, especially on cable logging operations [13
]. Cable logging is regularly used on slopes greater than 40%, which constitute approximately half of logging operations in the region [14
]. As cable logging occurs on steep slopes, manual tree felling is most commonly done by workers with chainsaws, and rigging crew workers set chokers (steel cables) around logs by hand before they are yarded up hill to a log landing (Figure 1
With a mix of ground workers and heavy equipment working alongside one another, often on steep slopes, several potential hazardous scenarios exist. These include injuries resulting from falling trees or trees moved by equipment or cables; kickback or other cutting injuries associated with chainsaws; falling live tree and snag (dead standing tree) hazards; logs, rocks, and other objects that are dislodged and roll down slope; rollover injuries caused when equipment tips over on steep slopes; and pinch-point injuries that occur beneath overhead equipment (e.g., the skyline carriage) or behind rotating machines (e.g., loaders, processors, and swing yarders). Several studies have found claims are most often filed for injuries related to being struck by or against objects, such as tree parts, snags, and logs, with many fatalities related to head injuries caused by falling trees [9
]. Injuries related to falling from equipment while doing maintenance and repair are among the most-common injuries on mechanized logging operations [8
]. ‘Not seen’ injury incidents occur because equipment operators face the difficult dual task of being aware of ground workers’ locations while focused on operating heavy machinery [17
Situational awareness (SA) can be described as the “state of understanding what is happening in an event with many actors and moving parts” [18
] (p. 1079). Endsley posits SA has three levels: (1) perception of elements in the environment (e.g., knowledge of terrain and where workers are); (2) comprehension of the current situation (i.e., the ability integrate and understand the meaning of the individual elements perceived in level 1); and (3) projection of future states, or the ability to use the integrated information from level 2 to make decisions consistent with operation goals [19
]. As Endsley explains
Acquiring and maintaining SA becomes increasingly difficult, however, as the complexity and dynamics of the environment increase. In dynamic environments, many decisions are required across a fairly narrow space of time, and tasks are dependent on an ongoing, up-to-date analysis of the environment. Because the state of the environment is constantly changing, often in complex ways, a major portion of the operator’s job becomes that of obtaining and maintaining good SA.
Logging operations often present dynamic environments wherein maintaining SA is difficult, yet critical for worker safety. Location-sharing devices, such as new Global Navigation Satellite System-Radio Frequency (GNSS-RF) technologies that share geographic coordinates and radio-frequency identification (RFID) transmitters capable of local relative positioning of worker proximity to equipment, have potential to increase workers’ SA on logging operations. GNSS-RF devices that facilitate location sharing in off-the-grid areas without cellular service include receivers that synchronize with mobile phones or tablets using Bluetooth and transmit GNSS locations throughout local networks, as well as dedicated radios with GNSS capabilities. These latter devices originated for military applications but are increasingly being considered for worker safety uses in natural resources.
Keefe et al. proposed the development of a system that would allow equipment operators to see locations of ground workers and other equipment on a digital display in real time using location-sharing devices [20
]. This system would increase SA during logging, thereby reducing the incidence of fatal and near-fatal injuries. Virtual geofences encompassing high-risk areas on logging operations have been evaluated as a mechanism to detect and alert operators to the presence of ground workers in hazardous areas [13
]. Zimbelman et al. expanded this concept to include detection of workers and equipment in motion through real-time proximity analysis [22
]. The movements of loggers and their proximity to multiple hazards during active logging operations was evaluated on three timber sales in northern Idaho [13
]. This study found ground workers spent 23% to 53% of their time in hazardous areas.
When little forest canopy is present, GNSS positions sent at intervals of one location every 2.5 s are sufficiently fast to characterize equipment movements, like the swinging boom of a log loader or processor [23
]. However, GNSS system positioning error and the radio signals used to transmit those location data in ad-hoc networks in the woods are affected by forest canopy characteristics and topography [24
]. Therefore, GNSS-based geofences should generally not be used to provide fine-resolution safety alerts to operators [13
]. Real-time location sharing may still help improve general SA on the jobsite and has been identified as an important area for research and development in forest operations [13
Several studies have established the technical basis for the kinds of situations in which it may be appropriate to use real-time location sharing of worker and equipment GNSS coordinates to improve safety on logging operations [13
]. Yet, for these systems to be further developed and used in practice, it is necessary to understand professional loggers’ perspectives on potential uses and limitations of location sharing and this has not yet been explored in the literature. Loggers are best qualified to identify tasks and patterns of movement during common logging activities that would most benefit from use of location sharing to improve SA and assist with injury avoidance, detection, and response. Their input can best inform the design of technical field experiments to quantify location-sharing accuracy and suitability for use in the hazard and response scenarios identified, and provide background for subsequent surveys to quantify and evaluate more nuanced hypotheses about technology adoption among this worker group. Identifying and characterizing human factors that currently contribute to logging injury incidents is an important next step for informed development of technology-based interventions intended to improve safety.
Therefore, this paper contributes to the literature by using in-depth interviews and surveys with professional logging contractors to (1) characterize current situations, conditions, and human factors that lead to logging injury incidents to identify hazard situations that could be mitigated using GNSS-RF or other location-sharing technologies; and (2) understand loggers’ perspectives on potential uses and limitations to using real-time location-sharing devices to improve safety in remote work environments. In addition to characterizing loggers’ perspectives on safety hazard situations, associated human factors, and the appropriateness of adopting real-time location-sharing technology, we used survey and interview results to identify, develop, and prioritize specific hazard scenarios for subsequent field experiments evaluating use of GNSS-RF technology on active logging operations.
This study was approved by the University of Idaho Institutional Review board (project 15-797). We adopted a concurrent mixed-methods approach, meaning we gathered interview and survey data simultaneously in the same period (February to April 2016). The purpose of the mixed-method approach was twofold: (1) Complementarity (e.g., a strength of quantitative survey data is that it can provide breadth while qualitative interview data can provide explanation and depth) and (2) triangulation (i.e., ability to compare quantitative and qualitative findings) [26
]. The methodology for each approach is described in depth below.
2.1. Interview Methods
We identified interviewees through their participation in the Idaho Logger Education to Advance Professionalism (LEAP) program. Many Idaho loggers participate in LEAP in part because it fulfills Idaho Pro-Logger accreditation requirements. Major forest landowners require Idaho logging contractors to have Pro-Logger accreditation to retain certification under several national and international sustainability programs, such as the Sustainable Forestry Initiative (SFI) and Forest Stewardship Council (FSC).
We purposefully selected 75 potential interviewees from a list of all 677 loggers who participated in Idaho LEAP programs from 2004 to 2015. The aim of this maximum variation sample was to ensure a range of perspectives and characteristics would be represented. For example, it was important both ground and cable logging system experiences were included since these systems are both used extensively in the study region. Once we had interviewed all willing participants from the purposeful sample, our data included a range of perspectives, but we had not yet reached theoretical saturation, which occurs when “gathering fresh data no longer spark new theoretical insights, nor reveal new…categories or concepts” [27
] (p. 167). Therefore, we expanded our interview sampling frame by randomly selecting loggers from the full list. Interviewing continued until we reached theoretical saturation.
We conducted in-depth interviews in person with 5 participants and by phone with 36 participants for a total of 41 interviews. Interviews lasted approximately 30–60 min. All interviews were audio recorded and transcribed except for one interviewee who preferred not to be recorded. In that case, detailed notes were used in the analysis instead of a transcript.
Interviews were semi-structured with open-ended questions and covered four primary topics: hazardous situations and conditions as well as common injuries; human factors that contribute to injury incidents; potential suitable and unsuitable applications of real-time location-sharing technologies for logging operations; and interest, concerns, and potential barriers to adopting these technologies on logging operations. Before the series of questions related to location-sharing technology, the interviewer described the technology and answered the interviewee’s questions. Some participants said they had seen demonstrations of real-time location-sharing technology at LEAP trainings. A brief first set of questions helped us track participant characteristics (years of logging experience, type of logging systems worked in, land ownership type worked in, and company size).
Semi-structured interviews allow flexibility to explore participants’ specific knowledge, experiences, and perspectives related to pre-defined topics. We asked participants the same questions, but not necessarily in the same order, and follow-up questions were developed spontaneously. The corresponding author conducted 28 interviews, and two student research assistants conducted the other 13 after participating in training to ensure quality and consistency across interviewers. The corresponding author continued training and supporting the student assistants throughout the data collection process, including meeting regularly to debrief and to discuss and compare preliminary analytical observations.
The corresponding author conducted the formal analysis of interview data using ATLAS.ti qualitative data analysis software. The analysis involved systematically identifying, labeling, and organizing themes in the data following an inductive approach [28
]. Initial coding was the first phase of the analysis, which occurred simultaneously with data collection. Initial coding involves developing codes, or short and precise labels, that categorize and summarize segments of data [27
]. Once all data was collected and initial coding completed, the next step was to compare, refine, and sort initial codes into themes. Next, the corresponding author conducted focused coding wherein the refined codes capturing main themes were used to sort through the interview data. The final step was to identify quotations that illustrated the most salient themes.
2.2. Survey Methods
We collected survey data using convenience sampling at six LEAP Update workshops held throughout northern Idaho in spring 2016 (Table 1
). The self-administered survey used closed- and open-ended questions to collect information on personal protective equipment (PPE) use, perspectives on potential factors contributing to logging injuries and common hazardous situations, and demographic and employment information. We identified the factors contributing to injuries and common hazardous situations covered on the survey based on literature reviews and Fatality Assessment and Control Evaluation (FACE) program reports [29
]. Respondents were asked “Based on your experience, on a scale from 1 to 5, how common is it for the following factors to contribute to injuries on logging operations in the Inland Northwest?” and “Based on your experience, on a scale from 1 to 5, how common are the following hazardous situations on logging operations in the Inland Northwest?” Respondents answered these questions on a five-point scale ranging from 1 (“not at all common”) to 5 (“very common”) and had the opportunity to list and describe additional hazardous situations and factors in a follow-up open-ended question. One purpose of these questions was to identify and prioritize safety situations for the field experiment component of the broader project. We calculated descriptive statistics for the survey data and created tables using Excel.
While the interview and survey methods were designed to be complementary, because the interviews were semi-structured with open-ended questions and conducted concurrently with the survey, the themes that emerged from the interview data were broader than the closed-ended answer options presented to respondents on the survey and some survey answer options did not emerge as salient interview themes. We now present the results.
We have identified several human factors that loggers perceive to be associated with injuries on logging operations in the Inland Northwest. Loggers involved in this study were generally supportive of the use of location-sharing technology to improve SA in specific scenarios. Development of new location-sharing technology and associated safety recommendations will have the highest likelihood of success if they account for the perspectives and concerns of logging contractors. Concerns about technology causing distraction or becoming a burden and cost of implementation are important considerations, and additional survey data collection to inform development of safety recommendations should focus on better characterizing the relative importance of these factors, related tradeoffs, relationships between the logger age demographic and technology adoption, and the potential impact of these factors on behaviors.
Emerging location-sharing devices range in quality, available features, and cost, with the price of individual units ranging from US $100 or less for smartphone-based solutions to US $10,000 or more for advanced, military-grade GNSS-RF radios. Determining the willingness of contractors to purchase devices for safety purposes and feasible price points is another important consideration for future research.
The results of the current study suggest subsequent field experimentation to characterize the suitability of emerging location-sharing technologies for mission-critical safety applications should prioritize improving SA related to the location and safety status of hand fallers and rigging crew workers on cable logging operations. For these individuals who are not protected by equipment cabs, fatal or near-fatal traumatic injuries can occur quickly. When visibility obstructions are present, injury of workers may initially go unnoticed by others at the job site. For that reason, it is important that technology solutions have relatively fast transmission rates (e.g., <1 location per 5 s) to improve the speed of injury detection, interactive hazard notifications, and response times.