- Email: [email protected]
Findings from a visibility survey in the construction industry
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
Contents lists available at ScienceDirect
Transportation Research Interdisciplinary Perspectives journal homepage: https://www.journals.elsevier.com/transportation-researchinterdisciplinary-perspectives
Findings from a visibility survey in the construction industry Mallorie Leduc, Brandon Vance, Tammy Eger, Alison Godwin
⁎
School of Human Kinetics, Laurentian University, Sudbury, Ontario, Canada
A R T I C L E
I N F O
Article history: Received 7 May 2019 Received in revised form 23 August 2019 Accepted 1 September 2019 Available online 19 October 2019 Keywords: Visibility Construction Fatality, machinery Safety
A B S T R A C T
The current study documented worker ratings of visibility on common pieces of construction equipment. Participants (n = 57) were recruited from a health and safety training facility to complete a custom visibility survey. Visibility scores around the machinery were consistently ranked lower by participants who reported working around the machine, as opposed to being an operator. Discrepancies between visibility rankings reported by workers who work around machinery and operators may indicate an area of priority for safety training to improve visibility knowledge among all workers. Crown Copyright © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction The dynamic nature of working conditions at worksites in the construction industry result in constant changes to the environment, activities and hazards (Lingard, 2013). There are often multiple work activities occurring simultaneously in the same or close locations potentially requiring different equipment, materials, and work crews (Lingard, 2013; Hinze and Teizer, 2011; Teizer and Cheng, 2015). Furthermore, the work activities often involve workers operating different types of equipment while others are performing job tasks on foot simultaneously. The interaction between equipment and workers-on-foot have led to troubling levels of struck-by accidents, resulting in the third highest cause of workplace fatalities in Ontario from 2007 to 2016 (IHSA, 2019). Hinze and Teizer (2011) completed a review of fatalities in the construction industry in the USA from 1990 to 2007. The results indicated the Occupational Safety and Health Administration investigated a total of 13,511 fatalities and of which, 659 fatalities were identified as visibilityrelated and 521 fatalities were further classified as a struck-by traveling equipment (Hinze and Teizer, 2011). Dump trucks were cited as the most commonly involved equipment with a total of 173 incidents (Hinze and Teizer, 2011). The large blind spot towards the rear and directly behind the transportation box have been noted as visibility issues during the operation of a dump truck (Hinze and Teizer, 2011). Visibility-related injuries have also been most often noted in earthmoving equipment, trucks, and forklifts (Hinze and Teizer, 2011). Many types of earthmoving equipment ⁎ Corresponding author. E-mail address: [email protected]. (A. Godwin).
present additional visibility issues related to their moving blind spots, which are created by the movable extensions of the equipment (Hinze and Teizer, 2011). Therefore, repeated vicinity checks to identify hazards and workers-on-foot are critical to continually assess the visibility of the surrounding environment (Hinze and Teizer, 2011). As a result of the potential for continuous and prolonged interactions between equipment operators and workers-on-foot, it is important that all workers in the vicinity of moving equipment have knowledge related to the available line of sight, and issues associated with the operation of construction equipment. It is recognized that the role of knowledge is critical in improving the likelihood of workers recognizing, and demonstrating safe work habits, or in avoiding unnecessary risks in the workplace (Goldenhar and Schulte, 1994). In contrast, a worker without knowledge or training related to their job tasks and work environment is unable to identify all unsafe conditions and potential hazards (Abdelhamid and Everett, 2000). Therefore, knowledge and training related to visibility issues during the operation of equipment is critical for all workers to have the ability to identify unsafe conditions and hazards. Within the mining industry, knowledge of visibility issues was found as a result of a thematic analysis to understand strategies for mining workers to stay safe in their perceived, high risk work environment (Haas and Yorio, 2016). A previous visibility survey in the mining industry identified those areas around the load-haul-dump that were considered to have very low visibility (Salmoni, 1999). The work by Haas (Haas and Yorio, 2016) found that knowing which areas were lower visibility, and thus, higher risk, was important as it would inform where the worker should stand to maximize the chance of being seen by passing equipment. On this premise, all workers on a worksite would benefit from understanding the visibility issues related
http://dx.doi.org/10.1016/j.trip.2019.100056 2590-1982/Crown Copyright © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
2. Methods
to different types of construction equipment in order to safely assess their dynamic work environment for hazards or other workers, and to prevent collision. Workers typically acquire safety knowledge and habits through formal occupational health and safety (OHS) training programs, peer observation or in experiencing an accident (Oliver et al., 2002; Olson et al., 2009; Reddy et al., 2012). Formal OHS training programs may not specifically address visibility issues, but based on the existing evidence, should seek to educate workers on areas of visibility and non-visibility around the equipment. Workers are most likely to rank OHS training and education as the most important component of a safety culture, especially when reinforced by OHS advisors, supervisors and union representatives (Dingsdag et al., 2008). Acquiring safety knowledge via peer instruction may be incomplete due to biases held by the existing employees and other myths that get passed on through an organization (Olson et al., 2009). Additionally, preliminary data taken in the construction sector suggested that there may be differences between how types of workers evaluated the visible and non-visible areas around their machinery (Vance et al., 2016). If safety knowledge is passed via peer instruction as suggested by Reddy (Dingsdag et al., 2008), then different perceptions of visibility may be a source of incomplete knowledge that affects a worker's safe movement on the worksite. The methods utilized in this study are easily adaptable to surveying individual workforces to determine the level of mismatch in visibility knowledge between different workers, who may be compared on any number of demographics (experience, age, operator status, etc.). The objectives of the current study were to determine whether equipment operators and workers-on-foot differed on the following measurements pulled from a visibility survey completed in the construction industry: i) perceived visibility ratings in areas around construction equipment, ii) visibility ratings during the operator's use of mirrors and iii) the identification of a suitable spotter location.
A survey was administered to construction workers participating in various types of health and safety courses in a training facility. Ethics for this project were obtained through the Laurentian University Research Ethics Board. Completed surveys including consent forms were returned from 57 participants. The survey was divided into four sections: background information, experience with visibility technology, safety practices in the workplace and equipment visibility plots. 2.1. Equipment visibility plot survey The equipment visibility plots component of the survey was modified from a previous mining visibility survey created by the research team (Salmoni, 1999). For the current project, the research team used a 12 m grid divided into 8 sectors, based on the methods described by the National Institute for Occupational Safety and Health (NIOSH) methods, centered at the driver's seated position (Health, N. I. f. O. S. a, 2009). Four types of commonly used construction equipment were included within the study; dump truck, loader, earth compactor, and excavator. Participants were asked to indicate whether they identified as an equipment operator or a workeron-foot (i.e. someone who worked around that particular piece of equipment; pedestrian, spotter, engineer, supervisor, etc.). 2.1.1. Equipment visibility plot survey: visibility rating Participants were shown a birds-eye view of each type of equipment (dump truck, loader, earth compactor, and excavator) on a blank circular plane picture, and asked to rate the visibility to each pie-shaped sector around the machine: front, front left, front right, left, right, rear, rear left and rear right (Fig. 1). Participants provided a rating ranging from 1 (very poor) to 5 (very good) for each sector around the equipment. For
Fig. 1. Visibility ratings for each piece of equipment (dump truck, loader, earth compactor, excavator). 2
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
difference existed between perceived visibility ratings of operator's vs worker's-on-foot for each equipment type.
further analysis, the front right, front and front left ratings were averaged to create a composite front sector score while the three rear sectors (rear right, rear and rear left) were combined for a composite rear sector score. Right and left sectors remained as originally scored, resulting in 4 sectors of analysis around the machine (front sector, rear sector, right sector, and left sector). Finally, an overall equipment visibility rating was calculated as the average visibility score across all sectors.
3. Results 3.1. Background information The population surveyed included construction workers (n = 57) attending health and safety training in the province of Ontario, Canada with an average age of 38.7 years (±16.4 yrs) and on average, 14.3 years (±18.7 yrs) working in the construction industry. Respondents were predominantly male (n = 50), with five females and two choosing not to report gender. Under the visibility rating section, participants were asked to identify as either an operator or worker-on-foot (work around, spotter, etc.) with those who left that question blank (unknown) being removed from subsequent analysis of sector ratings.
2.1.2. Equipment visibility plot survey: mirrors The usage of mirrors section of the survey also provided another circular, blank plot, and asked the participant to shade the sectors around each type of equipment that would be visible through the use of mirrors. 2.1.3. Equipment visibility plot survey: spotter location The final section provided a circular blank plot for each type of equipment and the participant indicated with an “X” mark, the area(s) where they would stand if they were tasked with spotting that machinery during a reversing maneuver. Data was scored based on whether the participant chose a position that was visible to the operator via direct gaze (score 2), blind spot with mirror view (score 1), or not visible at all via direct gaze or mirror (score 0). To determine whether a particular sector was available via direct gaze or mirror view, the measurement plots for construction equipment produced by NIOSH were consulted (Health, N. I. f. O. S. a, 2009). In cases of disagreement, the participant's own answer to what is visible via mirror was consulted (see above). Therefore, the spotter location scoring was based on a high score indicating that they would be in an optimal position either visible in a mirror or via direct gaze, while scores of zero indicated the participant chose a completely inappropriate location in which to position themselves while helping the machine reverse (i.e. they would not be visible in a mirror or via direct gaze). Participants were given a completed sample of these visibility sections (ratings, mirror and spotter location) to orient them to the task using a common, passenger-sized pick-up truck as an example.
3.2. Dump truck visibility ratings The difference in dump truck sector ratings between operators (n = 19) and workers-on-foot (n = 27) are depicted in Fig. 2. Workers-on-foot consistently rank their visibility within the sectors around the dump truck lower than operators. A Mann-Whitney U Test demonstrated that for the right (4.8 vs 4.4) and front (3.8 vs 3.2) sectors, the difference in ratings between operators and workers-on-foot was significant (p = 0.045 and p = 0.041). The overall rating of machine visibility was also significantly different (p = 0.002) with operators rating the dump truck as 3.78 out of 5 versus the workers-on-foot rating it at 3.23 out of 5. 3.3. Loader, excavator, and dozer visibility ratings Minimal differences existed between operators (n = 20) and workerson-foot (n = 21) for most sectors around the loader (Fig. 3), and the Mann-Whitney U Test revealed a significant difference only for the front sector (p = 0.033) where operators provided a 4.5 rating and workerson-foot rated it as 4.1. Although not significant between types of workers, both the excavator (n = 19 operators and n = 23 workers-on-foot) sector ratings (Fig. 4) and the dozer (n = 12 operators and n = 19 workers-onfoot) sector ratings (Fig. 5) demonstrated a trend towards operators rating the sectors higher on visibility scores than workers-on-foot. Mann-
2.2. Analysis Descriptive data of the participants was summed and presented below. Non-normal data distributions and largely ordinal data resulted in the use of the appropriate non-parametric tests. Mann-Whitney U Tests were completed on the ratings of visibility sectors to determine whether a significant 5
Average Sector Rating (out of 5)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Front Sector
Rear Sector Right Sector Sectors around Dump Truck Operator
Left Sector
Work Around
Fig. 2. Difference in dump truck sector ratings between operators and workers-on-foot. 3
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
5
X
4.5 Average Sector Rating (out of 5)
4 3.5 3 2.5 2 1.5 1 0.5 0 Front Sector
Rear Sector Right Sector Sectors around Loader Operator
Left Sector
Work Around
Fig. 3. Difference in loader sector ratings between operators and workers-on-foot.
Whitney U tests did not demonstrate significant differences on any sectors or on the average visibility rating for either machine.
3.5. Spotter location results The spotter location score results are summarized in Table 1 for each type of equipment. Across all types of equipment (dump truck, loader, excavator and dozer), the predominant spotter location score was a 1, indicating that the participants would position themselves in a location that was a blind spot via direct gaze to the operator but should be visible in the operator's mirror. However, the percentage of respondents scoring a 1 varied across the different types of machinery, with 96% for the dump truck, 79% for the loader and only 53% and 48% for the excavator and dozer. As many as 27% for the excavator and 36% for the dozer would position
3.4. Use of mirrors Since mirrors are not standardized across equipment or workplaces, the responses varied drastically by participant, and due to the freeform nature of the question, the responses were difficult to consistently score. Therefore, the responses were only used to provide context for answers on the subsequent section of the survey (spotter location).
5
Average Sector Rating (out of 5)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Front Sector
Rear Sector Right Sector Sectors around Excavator Operator
Left Sector
Work Around
Fig. 4. Difference in excavator sector ratings between operators and workers-on-foot. 4
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
5
Average Sector Rating (out of 5)
4.5 4
3.5 3 2.5 2 1.5 1 0.5
0 Front Sector
Rear Sector Right Sector Sectors around Dozer Operator
Left Sector
Work Around
Fig. 5. Difference in dozer sector ratings between operators and workers-on-foot.
are in line with their perceived knowledge about poor visibility. For instance, if workers-on-foot rank the right dump truck sector a value of 3.2 (compared to the operator's 3.8 score), then they may also be more cautious when working in this zone around a dump truck. On the other hand, if operators consistently think visibility is reasonable within a particular sector, when in fact, it is not, their complacency may increase with respect to continually assessing that area for pedestrian workers and hazards. The meaningfulness of the perceived visibility ratings from these two groups of workers can be further explored by comparing the values to the known visibility around a machinery, and the gold standard used for this comparison was from published NIOSH visibility plots (Health, N. I. f. O. S. a, 2009). Although visibility would vary between makes and models of machines, the research team chose average-sized machines for the comparison. For the dump truck, prior to collapsing the sectors into broader categories, operators averaged a rating of 2.5 (okay) for the rear right sector and 2.7 (okay) for the rear left areas. These ratings are reasonably high despite NIOSH visibility plots for a similar model suggesting the areas are complete blind spots for the operator of the dump truck (Health, N. I. f. O. S. a, 2009). The only available visibility to those areas is achieved through mirror checking. Participants were asked to rate the sectors based on direct visibility but nonetheless, may have been thinking about the use of mirrors when answering the question. Hence, the interpretation of these results may be limited. Likewise, operators rated the area directly behind the dump truck (rear sector) as a 1.6 out of 5 (i.e. very poor); however, there is zero visibility at all directly behind the machine, either by direct gaze by the operator or via a mirror. One might assume this should receive an average rating of closer to 1 (which was the lowest value on the scale provided). However, the survey did not provide a way for participants to provide a score of 0 for a particular sector when they felt there was truly no visibility in that area. It would only be through a camera system that visibility to the rear sector (directly behind the machine) could be achieved, and according to these findings, camera systems are not widespread in the construction industry with only 18% reporting that they “always use” one. Finally, the visibility ratings for all machinery (excavator, loader, dump truck and dozer) were generally rated as “very good” for the forward sectors from the operator perspective (left front, front and right front sectors). However, NIOSH visibility plots for the dump truck, loader and dozer indicate substantial blind spots to ground level for the forward sector (Health, N. I. f. O. S. a, 2009), and the excavator has limited visibility due to the
themselves in a position to which the operator had a direct gaze; however, it may not have been a particularly useful location to help with reversing (or spotting) the machinery. Of most concern were the respondents who selected to position themselves in a location that was not visible to the operator (spotter score of 0) in their direct view or via mirror: 4% for the dump truck, 17% for the dozer, and 20% for the excavator. 4. Discussion The current study documented workers' ranking of visibility in the different sectors around various types of construction equipment. Additionally, the appropriateness of the participants' response to the question about where they would stand to aid a reversing piece of machinery was evaluated. Results between participants who self-reported as an “operator” of that equipment or someone who was a “worker-on-foot” around the equipment were compared for differences. Discussion of the results are framed with respect to existing evidence surrounding the construction sector, including mandated protocols (Ministry of Labour (MOL), 1990). Significant differences in ratings of visibility in different sectors around equipment were found between operators vs workers-on-foot. Typically, across all machines and sectors, operators reported higher visibility rating scores (out of 5) than workers-on-foot. This rating reached a level of statistical significance for some specific areas (front and right sectors of dump truck, front sector on loader). As well, the average operator visibility rating across all dump truck sectors was 0.5 units higher than for workers-on-foot (p = 0.002). The findings mimic preliminary work on an additional 27 construction workers (Vance et al., 2016) and suggest that visibility may be perceived differently between these two types of workers. In the current study, visibility to most sectors was ranked as worse by workers-on-foot, which may work as a protective factor if their behaviour on the worksite Table 1 Spotter location scores. Spotter Score
Visibility
Dump truck
Loader
Excavator
Dozer
Not visible
4%
0%
20%
17%
Mirrors
96%
80%
53%
48%
Direct gaze
0%
20%
27%
36%
0 1 2
5
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
workers on a worksite. When mismatches are found between perceived visibility and actual visibility, as was the case in this work, it provides an avenue for workplaces or health and safety professionals to address the knowledge gap via interventions.
boom for the front right sector from the operator's position (Health, N. I. f. O. S. a, 2009) that is not reflected at all in the visibility ratings provided by participants in this study. These results suggest that both operators and workers-on-foot are not particularly skilled at gauging the level of forward visibility to ground level from all types of construction equipment. Further work should investigate whether individuals are better able to gauge visible areas to a common pedestrian height (1.5 m) compared to ground level blind spots. The survey method used here would also provide health and safety professionals a means by which they could poll members of their workforce to identify how they perceive visibility around common pieces of machinery with which they interact on a daily basis. The average sector ratings are easily comparable against this dataset, or against the NIOSH plots as a hands-on way to identify biases about visibility and safety knowledge (Health, N. I. f. O. S. a, 2009). In contrast, participants did a reasonable job of identifying a visible location in which to stand to perform the task of “backing up” the dump truck and loader, with 96% and 79% choosing a spotter location that would be visible by the operator without any visibility aids. However, the percentage of participants able to choose an appropriate (visible) position decreased for the dozer and the excavator, likely due to their more complex geometry and less predictable movement patterns. A concerning 20% of participants for the excavator, and 17% of participants for the dozer, selected a spotter position in a location that was not visible to the operator in their direct view or via a mirror. However, the capacity to translate threedimensional knowledge onto a two-dimensional birds-eye plot may be a challenging task. The conclusions stemming from the results of these plots may be limited due to how individual participants view and interpret these plots. Nonetheless, having workers think about the space around the machine in different ways will help reinforce a better understanding and knowledge of the visibility available to them. To this end, the research team has developed a three-dimensional virtual reality intervention that aims to impart this visibility knowledge in a more impactful medium. The visible and non-visible are displayed on the ground in a circular grid similar to the NIOSH plots (Health, N. I. f. O. S. a, 2009) which featured heavily in the evaluation piece of this work. As used in this study, the spotter location question can be a metric to determine whether the VR experience is a useful tool for improving knowledge about the visibility around machinery. Several limitations to the method and results must be addressed. Firstly, the participant numbers were low for a qualitative survey, but were typical of the expected response rate when gathering field data. As such, statistical comparisons were done with non-parametric procedures. The survey used, was not a validated tool but was based on a mining survey previously done in the field. A trial period of data collection was done with a similar survey on a total of 27 participants, and modifications to the survey were done to improve response rate and reduce the amount of time it would take to complete in a field situation. The results from the preliminary data corroborate the findings from the larger dataset of n = 57 in this article. One of the largest limitations to the quality of data is collected is in the assumptions made by participants when answering questions related to specific machinery. The survey listed a generic dump truck, loader, excavator and dozer for analysis, and used a corresponding picture that was representative of an average-sized machine for each of these. However, when participants filled out the visibility questions for each of those pieces of machinery, they may have been envisioning a much larger, or smaller machine, which would change their ratings, perhaps substantially. Likewise, mirrors are not standardized accessories for these machines and may be added-on in various locations after the fact to provide even more visibility than anticipated. Nonetheless, this work demonstrates an interesting way to measure a worker's perception of the visibility around workplace equipment. The survey method is easy to administer and analyze, and can be used to provide insight on possible differences in safety knowledge between the types of
5. Conclusion The current study sought to quantify the perceived visibility to different areas around equipment, perceived available visibility via mirrors, and the ability of workers to select an appropriate spotter location. The participants, recruited from the construction industry, were asked to identify as either equipment operators or individuals who were workers-on-foot. Participants who identified as operators of the piece of equipment, nearly always rated visibility as higher to each sector, when compared to the group who simply worked around the machinery. The identified mismatch between these two groups may impact how they each move and behave on a construction worksite, and this mismatch can be a targeted area of improvement for safety interventions in this industry. Both types of workers also appear to underestimate the amount of visibility restriction to ground level located in front of the operator's working position. The methodology presented here is easily adapted to any industry, and any type of industrial equipment. It can also be used as a scanning procedure for a workplace to identify a worker's understanding of the safety of the space in which they work. These findings can help inform training programs, or design interventions aimed at improving the knowledge of safe work practices in and around construction equipment. Funding This work was supported by the Ontario Ministry of Labour, Canada (14-R-004). References Abdelhamid, T.S., Everett, J.G., 2000. Identifying root causes of construction accident. J Constr Eng M. 126, 52–60. Dingsdag, D.P., Biggs, H.C., Sheahan, V.L., 2008. Understanding and defining OH&S competency for construction site positions: worker perceptions. Saf. Sci. 46, 619–633. Goldenhar, L.M., Schulte, P.A., 1994. Intervention research in occupational health and safety. J Occup Med. 36, 763–775. Haas, E.J., Yorio, P., 2016. Exploring the state of health and safety management system performance measurement in mining organizations. Saf. Sci. 83, 48–58. Health, N. I. f. O. S. a, 2009. Highway work zone safety: construction equipment visibility. http://www.cdc.gov/niosh/topics/highwayworkzones/bad/imagelookup.html, Accessed date: 6 November 2018. Hinze, J.W., Teizer, J., 2011. Visibility-related fatalities related to construction equipment. Saf. Sci. 49, 709–718. IHSA, 2019. Struck-by fatalities. http://www.ihsa.ca/topics_hazards/struck_bys.aspx, Accessed date: 7 May 2019. Lingard, H., 2013. Occupational health and safety in the construction industry. Construct Manag Econ. 31, 515-514. Ministry of Labour (MOL), 1990. Construction Projects Regulation O. Reg. 213/91. Ontario Gazette. 124 pp. 2081–2139. Oliver, A., Cheyne, A., Tomas, J.M., Cox, S., 2002. The effects of organizational and individual factors on occupational accidents. J. Occup. Organ. Psychol. 75, 473–488. Olson, R., Grosshuesch, A., Schmidt, S., Gray, M., Wipfli, B., 2009. Observational learning and workplace safety: the effects of viewing the collective behaviour of multiple social models on the use of personal protective equipment. J. Saf. Res. 40, 383–387. Reddy, R.K., Welch, D., Thorne, P., Ameratunga, S., 2012. Hearing protection use in manufacturing workers: a qualitative study. Noise Health. 14, 202. Salmoni, A., 1999. Underground Mobile Trackless Equipment Visibility Investigation. WSIB Research Advisory Council Grant. Teizer, J., Cheng, T., 2015. Proximity hazard indicator for workers-on-foot near miss interactions with construction equipment and geo-referenced hazard areas. Automat Constr. 60, 58–73. Vance, B., Nydam, C., Eger, T.T., Godwin, A.A., 2016. Examining construction workers' perception of line of sight around common pieces of machinery. Proceedings of the Association of Canadian Ergonomists 47th Annual Conference, 18–20 Oct.
6
Contents lists available at ScienceDirect
Transportation Research Interdisciplinary Perspectives journal homepage: https://www.journals.elsevier.com/transportation-researchinterdisciplinary-perspectives
Findings from a visibility survey in the construction industry Mallorie Leduc, Brandon Vance, Tammy Eger, Alison Godwin
⁎
School of Human Kinetics, Laurentian University, Sudbury, Ontario, Canada
A R T I C L E
I N F O
Article history: Received 7 May 2019 Received in revised form 23 August 2019 Accepted 1 September 2019 Available online 19 October 2019 Keywords: Visibility Construction Fatality, machinery Safety
A B S T R A C T
The current study documented worker ratings of visibility on common pieces of construction equipment. Participants (n = 57) were recruited from a health and safety training facility to complete a custom visibility survey. Visibility scores around the machinery were consistently ranked lower by participants who reported working around the machine, as opposed to being an operator. Discrepancies between visibility rankings reported by workers who work around machinery and operators may indicate an area of priority for safety training to improve visibility knowledge among all workers. Crown Copyright © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction The dynamic nature of working conditions at worksites in the construction industry result in constant changes to the environment, activities and hazards (Lingard, 2013). There are often multiple work activities occurring simultaneously in the same or close locations potentially requiring different equipment, materials, and work crews (Lingard, 2013; Hinze and Teizer, 2011; Teizer and Cheng, 2015). Furthermore, the work activities often involve workers operating different types of equipment while others are performing job tasks on foot simultaneously. The interaction between equipment and workers-on-foot have led to troubling levels of struck-by accidents, resulting in the third highest cause of workplace fatalities in Ontario from 2007 to 2016 (IHSA, 2019). Hinze and Teizer (2011) completed a review of fatalities in the construction industry in the USA from 1990 to 2007. The results indicated the Occupational Safety and Health Administration investigated a total of 13,511 fatalities and of which, 659 fatalities were identified as visibilityrelated and 521 fatalities were further classified as a struck-by traveling equipment (Hinze and Teizer, 2011). Dump trucks were cited as the most commonly involved equipment with a total of 173 incidents (Hinze and Teizer, 2011). The large blind spot towards the rear and directly behind the transportation box have been noted as visibility issues during the operation of a dump truck (Hinze and Teizer, 2011). Visibility-related injuries have also been most often noted in earthmoving equipment, trucks, and forklifts (Hinze and Teizer, 2011). Many types of earthmoving equipment ⁎ Corresponding author. E-mail address: [email protected]. (A. Godwin).
present additional visibility issues related to their moving blind spots, which are created by the movable extensions of the equipment (Hinze and Teizer, 2011). Therefore, repeated vicinity checks to identify hazards and workers-on-foot are critical to continually assess the visibility of the surrounding environment (Hinze and Teizer, 2011). As a result of the potential for continuous and prolonged interactions between equipment operators and workers-on-foot, it is important that all workers in the vicinity of moving equipment have knowledge related to the available line of sight, and issues associated with the operation of construction equipment. It is recognized that the role of knowledge is critical in improving the likelihood of workers recognizing, and demonstrating safe work habits, or in avoiding unnecessary risks in the workplace (Goldenhar and Schulte, 1994). In contrast, a worker without knowledge or training related to their job tasks and work environment is unable to identify all unsafe conditions and potential hazards (Abdelhamid and Everett, 2000). Therefore, knowledge and training related to visibility issues during the operation of equipment is critical for all workers to have the ability to identify unsafe conditions and hazards. Within the mining industry, knowledge of visibility issues was found as a result of a thematic analysis to understand strategies for mining workers to stay safe in their perceived, high risk work environment (Haas and Yorio, 2016). A previous visibility survey in the mining industry identified those areas around the load-haul-dump that were considered to have very low visibility (Salmoni, 1999). The work by Haas (Haas and Yorio, 2016) found that knowing which areas were lower visibility, and thus, higher risk, was important as it would inform where the worker should stand to maximize the chance of being seen by passing equipment. On this premise, all workers on a worksite would benefit from understanding the visibility issues related
http://dx.doi.org/10.1016/j.trip.2019.100056 2590-1982/Crown Copyright © 2019 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
2. Methods
to different types of construction equipment in order to safely assess their dynamic work environment for hazards or other workers, and to prevent collision. Workers typically acquire safety knowledge and habits through formal occupational health and safety (OHS) training programs, peer observation or in experiencing an accident (Oliver et al., 2002; Olson et al., 2009; Reddy et al., 2012). Formal OHS training programs may not specifically address visibility issues, but based on the existing evidence, should seek to educate workers on areas of visibility and non-visibility around the equipment. Workers are most likely to rank OHS training and education as the most important component of a safety culture, especially when reinforced by OHS advisors, supervisors and union representatives (Dingsdag et al., 2008). Acquiring safety knowledge via peer instruction may be incomplete due to biases held by the existing employees and other myths that get passed on through an organization (Olson et al., 2009). Additionally, preliminary data taken in the construction sector suggested that there may be differences between how types of workers evaluated the visible and non-visible areas around their machinery (Vance et al., 2016). If safety knowledge is passed via peer instruction as suggested by Reddy (Dingsdag et al., 2008), then different perceptions of visibility may be a source of incomplete knowledge that affects a worker's safe movement on the worksite. The methods utilized in this study are easily adaptable to surveying individual workforces to determine the level of mismatch in visibility knowledge between different workers, who may be compared on any number of demographics (experience, age, operator status, etc.). The objectives of the current study were to determine whether equipment operators and workers-on-foot differed on the following measurements pulled from a visibility survey completed in the construction industry: i) perceived visibility ratings in areas around construction equipment, ii) visibility ratings during the operator's use of mirrors and iii) the identification of a suitable spotter location.
A survey was administered to construction workers participating in various types of health and safety courses in a training facility. Ethics for this project were obtained through the Laurentian University Research Ethics Board. Completed surveys including consent forms were returned from 57 participants. The survey was divided into four sections: background information, experience with visibility technology, safety practices in the workplace and equipment visibility plots. 2.1. Equipment visibility plot survey The equipment visibility plots component of the survey was modified from a previous mining visibility survey created by the research team (Salmoni, 1999). For the current project, the research team used a 12 m grid divided into 8 sectors, based on the methods described by the National Institute for Occupational Safety and Health (NIOSH) methods, centered at the driver's seated position (Health, N. I. f. O. S. a, 2009). Four types of commonly used construction equipment were included within the study; dump truck, loader, earth compactor, and excavator. Participants were asked to indicate whether they identified as an equipment operator or a workeron-foot (i.e. someone who worked around that particular piece of equipment; pedestrian, spotter, engineer, supervisor, etc.). 2.1.1. Equipment visibility plot survey: visibility rating Participants were shown a birds-eye view of each type of equipment (dump truck, loader, earth compactor, and excavator) on a blank circular plane picture, and asked to rate the visibility to each pie-shaped sector around the machine: front, front left, front right, left, right, rear, rear left and rear right (Fig. 1). Participants provided a rating ranging from 1 (very poor) to 5 (very good) for each sector around the equipment. For
Fig. 1. Visibility ratings for each piece of equipment (dump truck, loader, earth compactor, excavator). 2
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
difference existed between perceived visibility ratings of operator's vs worker's-on-foot for each equipment type.
further analysis, the front right, front and front left ratings were averaged to create a composite front sector score while the three rear sectors (rear right, rear and rear left) were combined for a composite rear sector score. Right and left sectors remained as originally scored, resulting in 4 sectors of analysis around the machine (front sector, rear sector, right sector, and left sector). Finally, an overall equipment visibility rating was calculated as the average visibility score across all sectors.
3. Results 3.1. Background information The population surveyed included construction workers (n = 57) attending health and safety training in the province of Ontario, Canada with an average age of 38.7 years (±16.4 yrs) and on average, 14.3 years (±18.7 yrs) working in the construction industry. Respondents were predominantly male (n = 50), with five females and two choosing not to report gender. Under the visibility rating section, participants were asked to identify as either an operator or worker-on-foot (work around, spotter, etc.) with those who left that question blank (unknown) being removed from subsequent analysis of sector ratings.
2.1.2. Equipment visibility plot survey: mirrors The usage of mirrors section of the survey also provided another circular, blank plot, and asked the participant to shade the sectors around each type of equipment that would be visible through the use of mirrors. 2.1.3. Equipment visibility plot survey: spotter location The final section provided a circular blank plot for each type of equipment and the participant indicated with an “X” mark, the area(s) where they would stand if they were tasked with spotting that machinery during a reversing maneuver. Data was scored based on whether the participant chose a position that was visible to the operator via direct gaze (score 2), blind spot with mirror view (score 1), or not visible at all via direct gaze or mirror (score 0). To determine whether a particular sector was available via direct gaze or mirror view, the measurement plots for construction equipment produced by NIOSH were consulted (Health, N. I. f. O. S. a, 2009). In cases of disagreement, the participant's own answer to what is visible via mirror was consulted (see above). Therefore, the spotter location scoring was based on a high score indicating that they would be in an optimal position either visible in a mirror or via direct gaze, while scores of zero indicated the participant chose a completely inappropriate location in which to position themselves while helping the machine reverse (i.e. they would not be visible in a mirror or via direct gaze). Participants were given a completed sample of these visibility sections (ratings, mirror and spotter location) to orient them to the task using a common, passenger-sized pick-up truck as an example.
3.2. Dump truck visibility ratings The difference in dump truck sector ratings between operators (n = 19) and workers-on-foot (n = 27) are depicted in Fig. 2. Workers-on-foot consistently rank their visibility within the sectors around the dump truck lower than operators. A Mann-Whitney U Test demonstrated that for the right (4.8 vs 4.4) and front (3.8 vs 3.2) sectors, the difference in ratings between operators and workers-on-foot was significant (p = 0.045 and p = 0.041). The overall rating of machine visibility was also significantly different (p = 0.002) with operators rating the dump truck as 3.78 out of 5 versus the workers-on-foot rating it at 3.23 out of 5. 3.3. Loader, excavator, and dozer visibility ratings Minimal differences existed between operators (n = 20) and workerson-foot (n = 21) for most sectors around the loader (Fig. 3), and the Mann-Whitney U Test revealed a significant difference only for the front sector (p = 0.033) where operators provided a 4.5 rating and workerson-foot rated it as 4.1. Although not significant between types of workers, both the excavator (n = 19 operators and n = 23 workers-on-foot) sector ratings (Fig. 4) and the dozer (n = 12 operators and n = 19 workers-onfoot) sector ratings (Fig. 5) demonstrated a trend towards operators rating the sectors higher on visibility scores than workers-on-foot. Mann-
2.2. Analysis Descriptive data of the participants was summed and presented below. Non-normal data distributions and largely ordinal data resulted in the use of the appropriate non-parametric tests. Mann-Whitney U Tests were completed on the ratings of visibility sectors to determine whether a significant 5
Average Sector Rating (out of 5)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Front Sector
Rear Sector Right Sector Sectors around Dump Truck Operator
Left Sector
Work Around
Fig. 2. Difference in dump truck sector ratings between operators and workers-on-foot. 3
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
5
X
4.5 Average Sector Rating (out of 5)
4 3.5 3 2.5 2 1.5 1 0.5 0 Front Sector
Rear Sector Right Sector Sectors around Loader Operator
Left Sector
Work Around
Fig. 3. Difference in loader sector ratings between operators and workers-on-foot.
Whitney U tests did not demonstrate significant differences on any sectors or on the average visibility rating for either machine.
3.5. Spotter location results The spotter location score results are summarized in Table 1 for each type of equipment. Across all types of equipment (dump truck, loader, excavator and dozer), the predominant spotter location score was a 1, indicating that the participants would position themselves in a location that was a blind spot via direct gaze to the operator but should be visible in the operator's mirror. However, the percentage of respondents scoring a 1 varied across the different types of machinery, with 96% for the dump truck, 79% for the loader and only 53% and 48% for the excavator and dozer. As many as 27% for the excavator and 36% for the dozer would position
3.4. Use of mirrors Since mirrors are not standardized across equipment or workplaces, the responses varied drastically by participant, and due to the freeform nature of the question, the responses were difficult to consistently score. Therefore, the responses were only used to provide context for answers on the subsequent section of the survey (spotter location).
5
Average Sector Rating (out of 5)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0
Front Sector
Rear Sector Right Sector Sectors around Excavator Operator
Left Sector
Work Around
Fig. 4. Difference in excavator sector ratings between operators and workers-on-foot. 4
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
5
Average Sector Rating (out of 5)
4.5 4
3.5 3 2.5 2 1.5 1 0.5
0 Front Sector
Rear Sector Right Sector Sectors around Dozer Operator
Left Sector
Work Around
Fig. 5. Difference in dozer sector ratings between operators and workers-on-foot.
are in line with their perceived knowledge about poor visibility. For instance, if workers-on-foot rank the right dump truck sector a value of 3.2 (compared to the operator's 3.8 score), then they may also be more cautious when working in this zone around a dump truck. On the other hand, if operators consistently think visibility is reasonable within a particular sector, when in fact, it is not, their complacency may increase with respect to continually assessing that area for pedestrian workers and hazards. The meaningfulness of the perceived visibility ratings from these two groups of workers can be further explored by comparing the values to the known visibility around a machinery, and the gold standard used for this comparison was from published NIOSH visibility plots (Health, N. I. f. O. S. a, 2009). Although visibility would vary between makes and models of machines, the research team chose average-sized machines for the comparison. For the dump truck, prior to collapsing the sectors into broader categories, operators averaged a rating of 2.5 (okay) for the rear right sector and 2.7 (okay) for the rear left areas. These ratings are reasonably high despite NIOSH visibility plots for a similar model suggesting the areas are complete blind spots for the operator of the dump truck (Health, N. I. f. O. S. a, 2009). The only available visibility to those areas is achieved through mirror checking. Participants were asked to rate the sectors based on direct visibility but nonetheless, may have been thinking about the use of mirrors when answering the question. Hence, the interpretation of these results may be limited. Likewise, operators rated the area directly behind the dump truck (rear sector) as a 1.6 out of 5 (i.e. very poor); however, there is zero visibility at all directly behind the machine, either by direct gaze by the operator or via a mirror. One might assume this should receive an average rating of closer to 1 (which was the lowest value on the scale provided). However, the survey did not provide a way for participants to provide a score of 0 for a particular sector when they felt there was truly no visibility in that area. It would only be through a camera system that visibility to the rear sector (directly behind the machine) could be achieved, and according to these findings, camera systems are not widespread in the construction industry with only 18% reporting that they “always use” one. Finally, the visibility ratings for all machinery (excavator, loader, dump truck and dozer) were generally rated as “very good” for the forward sectors from the operator perspective (left front, front and right front sectors). However, NIOSH visibility plots for the dump truck, loader and dozer indicate substantial blind spots to ground level for the forward sector (Health, N. I. f. O. S. a, 2009), and the excavator has limited visibility due to the
themselves in a position to which the operator had a direct gaze; however, it may not have been a particularly useful location to help with reversing (or spotting) the machinery. Of most concern were the respondents who selected to position themselves in a location that was not visible to the operator (spotter score of 0) in their direct view or via mirror: 4% for the dump truck, 17% for the dozer, and 20% for the excavator. 4. Discussion The current study documented workers' ranking of visibility in the different sectors around various types of construction equipment. Additionally, the appropriateness of the participants' response to the question about where they would stand to aid a reversing piece of machinery was evaluated. Results between participants who self-reported as an “operator” of that equipment or someone who was a “worker-on-foot” around the equipment were compared for differences. Discussion of the results are framed with respect to existing evidence surrounding the construction sector, including mandated protocols (Ministry of Labour (MOL), 1990). Significant differences in ratings of visibility in different sectors around equipment were found between operators vs workers-on-foot. Typically, across all machines and sectors, operators reported higher visibility rating scores (out of 5) than workers-on-foot. This rating reached a level of statistical significance for some specific areas (front and right sectors of dump truck, front sector on loader). As well, the average operator visibility rating across all dump truck sectors was 0.5 units higher than for workers-on-foot (p = 0.002). The findings mimic preliminary work on an additional 27 construction workers (Vance et al., 2016) and suggest that visibility may be perceived differently between these two types of workers. In the current study, visibility to most sectors was ranked as worse by workers-on-foot, which may work as a protective factor if their behaviour on the worksite Table 1 Spotter location scores. Spotter Score
Visibility
Dump truck
Loader
Excavator
Dozer
Not visible
4%
0%
20%
17%
Mirrors
96%
80%
53%
48%
Direct gaze
0%
20%
27%
36%
0 1 2
5
M. Leduc et al.
Transportation Research Interdisciplinary Perspectives 2 (2019) 100056
workers on a worksite. When mismatches are found between perceived visibility and actual visibility, as was the case in this work, it provides an avenue for workplaces or health and safety professionals to address the knowledge gap via interventions.
boom for the front right sector from the operator's position (Health, N. I. f. O. S. a, 2009) that is not reflected at all in the visibility ratings provided by participants in this study. These results suggest that both operators and workers-on-foot are not particularly skilled at gauging the level of forward visibility to ground level from all types of construction equipment. Further work should investigate whether individuals are better able to gauge visible areas to a common pedestrian height (1.5 m) compared to ground level blind spots. The survey method used here would also provide health and safety professionals a means by which they could poll members of their workforce to identify how they perceive visibility around common pieces of machinery with which they interact on a daily basis. The average sector ratings are easily comparable against this dataset, or against the NIOSH plots as a hands-on way to identify biases about visibility and safety knowledge (Health, N. I. f. O. S. a, 2009). In contrast, participants did a reasonable job of identifying a visible location in which to stand to perform the task of “backing up” the dump truck and loader, with 96% and 79% choosing a spotter location that would be visible by the operator without any visibility aids. However, the percentage of participants able to choose an appropriate (visible) position decreased for the dozer and the excavator, likely due to their more complex geometry and less predictable movement patterns. A concerning 20% of participants for the excavator, and 17% of participants for the dozer, selected a spotter position in a location that was not visible to the operator in their direct view or via a mirror. However, the capacity to translate threedimensional knowledge onto a two-dimensional birds-eye plot may be a challenging task. The conclusions stemming from the results of these plots may be limited due to how individual participants view and interpret these plots. Nonetheless, having workers think about the space around the machine in different ways will help reinforce a better understanding and knowledge of the visibility available to them. To this end, the research team has developed a three-dimensional virtual reality intervention that aims to impart this visibility knowledge in a more impactful medium. The visible and non-visible are displayed on the ground in a circular grid similar to the NIOSH plots (Health, N. I. f. O. S. a, 2009) which featured heavily in the evaluation piece of this work. As used in this study, the spotter location question can be a metric to determine whether the VR experience is a useful tool for improving knowledge about the visibility around machinery. Several limitations to the method and results must be addressed. Firstly, the participant numbers were low for a qualitative survey, but were typical of the expected response rate when gathering field data. As such, statistical comparisons were done with non-parametric procedures. The survey used, was not a validated tool but was based on a mining survey previously done in the field. A trial period of data collection was done with a similar survey on a total of 27 participants, and modifications to the survey were done to improve response rate and reduce the amount of time it would take to complete in a field situation. The results from the preliminary data corroborate the findings from the larger dataset of n = 57 in this article. One of the largest limitations to the quality of data is collected is in the assumptions made by participants when answering questions related to specific machinery. The survey listed a generic dump truck, loader, excavator and dozer for analysis, and used a corresponding picture that was representative of an average-sized machine for each of these. However, when participants filled out the visibility questions for each of those pieces of machinery, they may have been envisioning a much larger, or smaller machine, which would change their ratings, perhaps substantially. Likewise, mirrors are not standardized accessories for these machines and may be added-on in various locations after the fact to provide even more visibility than anticipated. Nonetheless, this work demonstrates an interesting way to measure a worker's perception of the visibility around workplace equipment. The survey method is easy to administer and analyze, and can be used to provide insight on possible differences in safety knowledge between the types of
5. Conclusion The current study sought to quantify the perceived visibility to different areas around equipment, perceived available visibility via mirrors, and the ability of workers to select an appropriate spotter location. The participants, recruited from the construction industry, were asked to identify as either equipment operators or individuals who were workers-on-foot. Participants who identified as operators of the piece of equipment, nearly always rated visibility as higher to each sector, when compared to the group who simply worked around the machinery. The identified mismatch between these two groups may impact how they each move and behave on a construction worksite, and this mismatch can be a targeted area of improvement for safety interventions in this industry. Both types of workers also appear to underestimate the amount of visibility restriction to ground level located in front of the operator's working position. The methodology presented here is easily adapted to any industry, and any type of industrial equipment. It can also be used as a scanning procedure for a workplace to identify a worker's understanding of the safety of the space in which they work. These findings can help inform training programs, or design interventions aimed at improving the knowledge of safe work practices in and around construction equipment. Funding This work was supported by the Ontario Ministry of Labour, Canada (14-R-004). References Abdelhamid, T.S., Everett, J.G., 2000. Identifying root causes of construction accident. J Constr Eng M. 126, 52–60. Dingsdag, D.P., Biggs, H.C., Sheahan, V.L., 2008. Understanding and defining OH&S competency for construction site positions: worker perceptions. Saf. Sci. 46, 619–633. Goldenhar, L.M., Schulte, P.A., 1994. Intervention research in occupational health and safety. J Occup Med. 36, 763–775. Haas, E.J., Yorio, P., 2016. Exploring the state of health and safety management system performance measurement in mining organizations. Saf. Sci. 83, 48–58. Health, N. I. f. O. S. a, 2009. Highway work zone safety: construction equipment visibility. http://www.cdc.gov/niosh/topics/highwayworkzones/bad/imagelookup.html, Accessed date: 6 November 2018. Hinze, J.W., Teizer, J., 2011. Visibility-related fatalities related to construction equipment. Saf. Sci. 49, 709–718. IHSA, 2019. Struck-by fatalities. http://www.ihsa.ca/topics_hazards/struck_bys.aspx, Accessed date: 7 May 2019. Lingard, H., 2013. Occupational health and safety in the construction industry. Construct Manag Econ. 31, 515-514. Ministry of Labour (MOL), 1990. Construction Projects Regulation O. Reg. 213/91. Ontario Gazette. 124 pp. 2081–2139. Oliver, A., Cheyne, A., Tomas, J.M., Cox, S., 2002. The effects of organizational and individual factors on occupational accidents. J. Occup. Organ. Psychol. 75, 473–488. Olson, R., Grosshuesch, A., Schmidt, S., Gray, M., Wipfli, B., 2009. Observational learning and workplace safety: the effects of viewing the collective behaviour of multiple social models on the use of personal protective equipment. J. Saf. Res. 40, 383–387. Reddy, R.K., Welch, D., Thorne, P., Ameratunga, S., 2012. Hearing protection use in manufacturing workers: a qualitative study. Noise Health. 14, 202. Salmoni, A., 1999. Underground Mobile Trackless Equipment Visibility Investigation. WSIB Research Advisory Council Grant. Teizer, J., Cheng, T., 2015. Proximity hazard indicator for workers-on-foot near miss interactions with construction equipment and geo-referenced hazard areas. Automat Constr. 60, 58–73. Vance, B., Nydam, C., Eger, T.T., Godwin, A.A., 2016. Examining construction workers' perception of line of sight around common pieces of machinery. Proceedings of the Association of Canadian Ergonomists 47th Annual Conference, 18–20 Oct.
6