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International Journal of Injury Control and Safety Promotion Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/nics20
Safety concerns related to modular/prefabricated building construction a
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Maryam Mirhadi Fard , Seyyed Amin Terouhid , Charles J. Kibert & Hamed Hakim
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Rinker School of Construction Managemnet, University of Florida, Gainesville, FL, USA Published online: 24 Jun 2015.
Click for updates To cite this article: Maryam Mirhadi Fard, Seyyed Amin Terouhid, Charles J. Kibert & Hamed Hakim (2015): Safety concerns related to modular/prefabricated building construction, International Journal of Injury Control and Safety Promotion, DOI: 10.1080/17457300.2015.1047865 To link to this article: http://dx.doi.org/10.1080/17457300.2015.1047865
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International Journal of Injury Control and Safety Promotion, 2015 http://dx.doi.org/10.1080/17457300.2015.1047865
Safety concerns related to modular/prefabricated building construction Maryam Mirhadi Fard, Seyyed Amin Terouhid*, Charles J. Kibert and Hamed Hakim Rinker School of Construction Managemnet, University of Florida, Gainesville, FL, USA
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(Received 1 August 2014; accepted 25 March 2015) The US construction industry annually experiences a relatively high rate of fatalities and injuries; therefore, improving safety practices should be considered a top priority for this industry. Modular/prefabricated building construction is a construction strategy that involves manufacturing of the whole building or some of its components off-site. This research focuses on the safety performance of the modular/prefabricated building construction sector during both manufacturing and on-site processes. This safety evaluation can serve as the starting point for improving the safety performance of this sector. Research was conducted based on Occupational Safety and Health Administration investigated accidents. The study found 125 accidents related to modular/prefabricated building construction. The details of each accident were closely examined to identify the types of injury and underlying causes. Out of 125 accidents, there were 48 fatalities (38.4%), 63 hospitalized injuries (50.4%), and 14 non-hospitalized injuries (11.2%). It was found that, the most common type of injury in modular/prefabricated construction was ‘fracture’, and the most common cause of accidents was ‘fall’. The most frequent cause of cause (underlying and root cause) was ‘unstable structure’. In this research, the accidents were also examined in terms of corresponding location, occupation, equipment as well as activities during which the accidents occurred. For improving safety records of the modular/prefabricated construction sector, this study recommends that future research be conducted on stabilizing structures during their lifting, storing, and permanent installation, securing fall protection systems during on-site assembly of components while working from heights, and developing training programmes and standards focused on modular/prefabricated construction. Keywords: safety performance; modular construction; prefabrication; safety cases
Introduction The construction industry is one of the most dangerous industries in terms of safety. In 2012, the construction industry had the highest count of fatal work-related injuries (see Figure 1) (U.S. Bureau of Labor Statistics, 2014a). Construction accidents included but were not limited to falls from roofs and other structures, falls from scaffolds, electrocution, improperly operated power tools, and working in close proximity to heavy equipment such as loader, cranes, and forklifts. Key factors that cause hazards include changing and unfamiliar work environment, exposure to severe weather conditions, and using unskilled and temporary workers. Modular/prefabricated building construction is a construction strategy that involves the manufacturing of buildings or building components, generally taking place at a factory or a specialized facility remote from the building site (Florida, 2004; Tang & Chamberlain, 2003). This construction strategy has been practiced in the construction industry for decades. Prior to building assembly, the site and the foundation of the building are usually completed.
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Modular/prefabricated buildings differ from mobile buildings, such as mobile homes. Mobile buildings usually contain integrated frames and axles for transport, which also function as structural floor support. In contrast, a modular building is similar to on-site stick-built construction; and when it arrives at its final location, it is hoisted off its conveying trailer and installed on its foundation (Becker, Fullen, & Takacs, 2003). Therefore, modular/prefabricated building construction involves both offsite and on-site work. According to Freedonia’s research study (2013), modular/prefabricated housing is forecasted to reach 140,000 units in 2017 representing 14% annual growth from 2012. A survey conducted by McGraw Hill Construction in 2011 reported that increased productivity, improved safety, and greater return on investments were propelling this increase. This rapid growth calls for more trained and skilled workers who are familiar with proper construction techniques and related safety risks. Modular/prefabricated building construction is usually claimed to have a safer work environment compared to traditional on-site building construction due to the following
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Figure 1. Number and rate of fatal occupational injuries, by industry sector, 2012 (U.S. Bureau of Labor Statistics, 2014a).
factors (McGraw Hill Construction, 2013; Modular Building Institute, 2014; Vanguard Modular Building Systems, 2014): stable work location, where workers are used to their tasks and are familiar with the risks, avoiding work in tight spaces at the site, performing off-site or on-ground assembly instead of working from heights, not being exposed to harsh weather, easier ways to monitor unsafe activities, less spent time on construction site (30% 50% reduction) fewer contractors and workers required on site. Despite the potentials of this construction strategy to improve safer practices, there are still some safety risks involved in off-site and on-site jobs calling for more preventive actions and developing appropriate safety procedures. The main motivation for this study is the rapid growth of the modular/prefabricated building construction and the lack of research in the literature addressing safety concerns related to this industry. The purpose of this research is to investigate the type of dangers and safety risks involved in modular/prefabricated building construction during both manufacturing and on-site processes. Traditional buildings with prefabricated components such as precast components have also been considered in this study. Results of this study can be useful in developing preventive action plans and creating safer work conditions in this industry.
Literature review The existing literature of construction safety includes only a few cases addressing safety risks and hazards in the modular/prefabricated construction sector. In 2003, Becker et al. (2003) conducted a survey (questionnaires and interviews) to identify hazards faced by workers specific to modular home installation. The study did not cover safety issues related to off-site jobs. According to their research, the major hazards in modular home installation include being struck by a tilt-up roof while securing it in place, falls from roofs and attic areas, struck by objects during hoisting and rigging of large items, and falls from ladders. According to a survey about safety management in the construction industry conducted by McGraw Hill Construction (2013), 50% of the respondents believed that prefabrication and modularization have better safety performance compared to traditional construction. Only 4% of the contractors using prefabricated or modularization claimed that this method of construction has negative impacts on safety performance. The respondents in the survey were asked to indicate three parameters impacting modular/prefabricated safety. The highest percentage (78%) of the general contractors responding to the survey considered ‘complex assembly done at ground level/offsite’ as one of the attributes of prefabrication and modularization which increases safety performance, while 59% of specialty contractors considered this parameter as an impacting factor. 69% of specialty contractors and 69% of general contractors believed that the ‘fewer workers’ onsite working on different aspects of building’ is also a factor in improving modular/prefabricated construction
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International Journal of Injury Control and Safety Promotion safety. 58% of general contractors and 47% of specialty contractors indicated that ‘reduced need to work from heights’ is another influencing factor on the safety performance of modular/prefabricated construction. Manufacturing improvement concepts, such as lean manufacturing, may result in a safer work environment. In their paper, James, Ikuma, Nahmens, and Aghazadeh (2012) showed that after implementing lean approaches in a modular homebuilding factory, for some of the stations, there was a significant reduction in the worker exposure to risks. Among the standards of the Occupational Safety and Health Administration (OSHA) Code of Federal Regulations 29, there are some safety standards related to prefabricated construction such as: part 1926, subpart Q, standard number 1926-704: Requirements for Precast Concrete and standard number 1926-705: Requirements for Lift-Slab Operations (C.F.R. 29, Part 1926). However, some of the other standards are general safety practices, which are also applicable to modular/prefabricated building construction. Examples include part 1926 subpart M Fall Protection, 1910.23: Guarding Floor and Wall Openings and Holes, and safety standard 1910.213 Woodworking Machinery Requirements (C.F.R. 29, Part 1926; C.F.R. 29, Part 1910). Objectives and methodology The main objective of this research is to investigate the safety concerns and root causes of work-related injuries in modular/prefabricated building construction. Identifying improper safety practices is the key step in improving safety performance of this sector. Injuries and fatalities occurred on US jobsites are recorded by OSHA. OSHA is a federal agency responsible for the enforcement of safety and health legislation. To achieve the objective of this study, the authors were looking for an accident database containing corresponding records, explanations, and detailed data of the occurred accidents. OSHA has a programme entitled ‘Injuries, Illnesses, and Fatalities’, which provides annual data on the rate and number of work related injuries, illnesses, and fatal injuries by incident, industry, geography, occupation, and other attributes. The database associated with the programme includes only data and it does not provide any explanations of particular accidents. In addition, the fatality data have not separately been provided for each and every industry. For instance, there is no specific fatality data for pre-manufactured wood building manufacturing industry (NAICS 321992). Therefore, for the purpose of this study, another OSHA database, entitled ‘Fatality and Catastrophe Investigation Summaries’ was utilized. However, locating precise and comprehensive data related specifically to the modular/prefabricated building construction sector in that
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database was still difficult. The database does not usually separate accident data of traditional building construction from the data associated with modular/prefabricated construction. It is worth mentioning that, during the searching process, the authors came across several accidents related to the modular/prefabricated construction while they were listed under completely different Standard Industrial Classification (SIC)/North American Industry Classification System (NAICS) codes. The OSHA-investigated accidents in the above-mentioned database were closely examined to identify areas in modular/prefabricated building construction for improving safety performance. The database allows conducting computer-based word-specific search in the abstract and description sections of the accidents. It also allows to search in SIC/NAICS codes, event dates, and inspection numbers. This research focuses on the injuries and fatalities occurred from 2002 to 2013. The keywords that were used for the purpose of this research included: prefabricated, modular, panelized, precut, factory built, tilt-up building, and precast. The search was also conducted for the SIC code of 2452 (NAICS 321992): Prefabricated Wood Buildings. The result of this search function formed the feed database for this study including 125 injury cases. Since personal injuries involved in all the cases, in this paper, the terminology of ‘accident’ is used for them (U.S. Department of Labor, 2014). The description of each accident was closely studied from the following aspects: degree and type of the injury, cause and root cause of the injury, fall height and location where fall occurred in the accidents involving fall, type of equipment involved in the accident, activity/Activities taking place at the time of the accident, location of the accident, the year in which the accident happened, type of occupation involved in the accident, end-use of the building under construction, An example of OSHA reported accident is as follows (U.S. Department of Labor, 2014): ‘On September 9, 2009, Employee #1 was exiting a modular home on the manufacturer’s lot. She stepped forward out of the doorway onto a stepladder, while holding onto the door frame with her left hand. The ladder fell. The ring on Employee #1’s left index finger became caught on the door striker plate. The flesh was pulled off of Employee #1’s finger by the ring as she fell. She was hospitalized for the amputation of her finger to the first knuckle’.
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Figure 2. Frequency of the modular/prefabricated accidents by year.
Results After studying the details of each accident in the above-referenced database, the results were analysed and categorized. Out of 125 accidents, there were 48 fatalities (38.4%), 63 hospitalized injuries (50.4%), and 14 non-hospitalized injuries (11.2%). Although, the search was conducted for the accidents occurred from 2002 to 2013, the cases found belong to the time period between 2003 and 2012. Figure 2 depicts the distribution of the accidents during this time period. As illustrated by this figure, 2007 has the highest accident rate associated with modular/prefabricated building construction (21.6%) compared to the other years.
Injury types The types of injuries occurred are categorized and summarized in Figure 3. More than 43% of the injuries were
Figure 3. Injury types and their frequencies.
fractures. Approximately 19% of the injuries are grouped under the ‘Other’ category. These injuries were different from the identified categories. Some of these injuries include, but are not limited to, animal- and insect-related accidents and heat stroke. Unknown injuries were also categorized in this group. The injury types were also investigated based on the location of the accidents: on-site and manufacturing plants (see Figures 4 and 5). Fracture was the most common type of injury in the on-site accidents. In the accidents at manufacturing plants, both amputation and fracture were the most common injury types.
Accident causes For the purpose of this research, the reported accidents were carefully categorized and analysed. The causes were studied at two levels: ‘cause’ and ‘cause of cause’. This comprehensive analysis helps modular/prefabricated construction contractors in the following ways: to understand majority of the safety risks involved in this industry, to develop a comprehensive and preventive safety programme, to develop alternate designs and technical procedures to address safety concerns. Figure 6 shows the causes of the reported accidents. As this figure indicates, 44% of the causes were ‘fall’, and 36% were ‘struck by object/equipment (non-vehicle)’. The causes of the accidents were also analysed based on the location of the accidents: manufacturing plant or on-site.
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Figure 4. On-site injury types and their frequencies.
Figure 5. Injury types and their frequencies at manufacturing plants.
Figure 6. Accidents’ causes and their frequencies.
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Figure 7. On-site accidents’ causes and their frequencies.
‘Fall’ accounted for 48.1% and ‘struck by object/equipment (non-vehicle)’ accounted for 39% of the on-site accidents, whereas ‘struck by object/equipment (non-vehicle)’ accounted for 36.4% and ‘caught in equipment/object/material’ accounted for 22.7% of the accidents occurred at the manufacturing plants (see Figures 7 and 8). As mentioned before, the cause of cause was also analysed to discover the original root causes. Three of the reported accidents had two different root causes which have been taken into account in this analysis. As shown in Figure 9, the root cause was not clearly determined for
27.2% of the accidents. The cause of 24.8% of the accidents was ‘unstable structure’. ‘Unsecured object/equipment/tool’ had also a high frequency rate compared to the other underlying causes. In the on-site accidents, the highest rate (35.1%) of the underlying causes was ‘unstable structure’, whereas, in manufacturing plants’ accidents, 31.8% of the underlying causes was unknown and 22.7% was ‘unsecured object/ equipment/tool’ (see Figures 10 and 11). There were 28 accidents (22.4%) involving ‘collapse of structure’. Seven of these accidents (25%) stated that the
Figure 8. Accidents’ causes and their frequencies at manufacturing plants.
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Figure 9. Accidents’ cause of cause and their frequencies.
‘collapse of structure’ was due to unstable and loose structure connections. In six of these accidents, lack or deficient bracing was the result of the ‘collapse of structure’ and two of the accidents involving ‘collapse of structure’ described that the unsupported structure was the cause of collapse. In 4 of the accidents out of 28 accidents involving ‘collapse of structure’, the collapse occurred during hoisting process. Three of them stated that hoisting hook was caught in another safety eye and two of the accidents stated that the structure or its support was broken and the broken structure or support caused the collapse.
Figure 10. On-site accidents’ cause of cause and their frequencies.
Fall investigation For 23.6% of the fall accidents, the root cause was unknown. Among the fall accidents with known root cause, ‘unstable structure’ was the most common underlying cause, and ‘not using personal protective equipment (PPE)’ was the second most common one (see Figure 12). Since ‘fall’ was very frequent in the accidents referenced above, a more detailed analysis was conducted on the accidents involving ‘fall’. In 25.5% of these accidents, the fall height was in the range of 1.5 3 m; in 20.0%, the fall height was 3 4.6 m; and in 12.7% of the fall
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Figure 11. Accidents’ cause of cause and their frequencies at manufacturing plants.
accidents, the fall height was not specified (see Figure 13). The places, where the fall accidents occurred, were also analysed. As Figure 14 depicts, approximately 35% of the falls were from roofs and 25% were from structures other than roofs. Occupations Table 1 shows the types of occupations involved in the accidents along with their rates. In 35.2% of the accidents, the occupation was not reported. In 15.2% of the accidents, a ‘construction labourer’ was involved. Based on
Figure 12. The causes of fall accidents and their frequencies.
the result, carpenters also have a high risk of accident (12.8%). In the on-site accidents, ‘carpenters’ and ‘construction labourer’ were the occupations with the high rates of accidents. At manufacturing plants, ‘carpenters’ and ‘assemblers’ were the occupation with high rates. In 2013, the unionization rate of the construction industry was 14.1% (U.S. Bureau of Labor Statistics, 2014b). Although the unionization rate of modular/prefabricated building construction is unknown for the years 2002 2013, 82% of the workers involved in the accidents were non-union workers and 18% were union workers.
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Figure 13. Heights of falls and their frequencies.
Equipment The data were also examined to identify the equipment types and their frequencies involved in the accidents. In 27% of the accidents, equipment was involved. Figure 15 summarizes the types and frequency of the equipment involved. Forklifts, as heavy equipment, had the highest accident frequency rates, 23.5% of the accidents involving equipment. Saws were the equipment with the second highest accident rate of 20.6%. The types of saws involved include table saw, circular saw, skill saw, up-cut saw, and pop saw. In the on-site accidents, forklift and in manufacturing plants’ accidents, saw had the highest accident frequency rates (see Figures 16 and 17). Type of buildings Safety standards are often stricter in commercial settings. Hazards in residential building may therefore be unique.
Figure 14. Locations where fall happened from and their frequencies.
(Grant & Hinze, 2014). However, this may not be true for modular/prefabricated building construction. In this construction sector, based on the building’s design, commercial buildings usually have larger and heavier prefabricated components/modular components compared to residential buildings. As a result, hoisting, transportation, and installation of large prefabricated components in commercial construction may pose additional risks of accidents. In this research, the end-uses of the buildings under construction were also examined to determine the type of building with the highest safety risk. Figure 18 shows the distribution of the accidents by end use of the building. The highest rate was 31.2%, which was associated with commercial buildings. Because the type of the building was not identified in 23.2% of the accidents and the portion of residential and commercial buildings in modular/ prefabricated building construction is unknown, making conclusion in this section is premature and needs further investigation.
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Table 1. Occupation types involved in the accidents and their frequencies.
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Occupation Assemblers Carpenters Construction labourers Construction trades, not elsewhere classified (N.E.C.) Crane and tower operators Drywall installers Electricians Fabricating machine operators Foreman Hand moulders and shapers, except jewellers Heating, air conditioning, and refrigeration mechanics Helpers, construction trades Industrial truck and tractor equipment operators Iron worker Labourers, except construction Machine operators, not specified
Frequency
Occupation
Frequency
1.6% 12.8% 15.2% 2.4% 1.6% 0.8% 2.4% 0.8% 0.8% 0.8%
Miscellaneous hand working occupations Miscellaneous woodworking machine operators Nailing and tacking machine operators Occupation not reported Plumbers, pipefitters, and steamfitters Production inspectors, checkers, and examiners Roofers Structural metal workers Supervisors, carpenters, and related workers Supervisors, food preparation, and service occupation
0.8% 0.8% 0.8% 35.2% 0.8% 0.8% 2.4% 2.4% 2.4% 0.8%
0.8% 1.6% 0.8% 1.6% 2.4% 0.8%
Out of 125 studied accidents, 18 accidents (14.4%) were directly related to the modular building. The description section of the remaining accidents did not contain any information indicating that they were related to modular building; however, they all were related to prefabricated, precast, and tilt up building/components.
Supervisors, mechanics, and repairers Supervisors, production occupations Truck drivers, heavy Truck drivers, light Welders and cutters
0.8% 0.8% 0.8% 0.8% 2.4%
prefabricated building or components. The manufacturing process (16.8%) ranked second in terms of safety risk (see Figure 19). This result can be considered as evidence that off-site construction is potentially safer than on-site operations.
Location Activity Based on the analysis, the majority of the accidents (57.6%) occurred during installation of modular/
The locations of the accidents were also analysed. California had the highest accident rate among all 32 states having reported accidents. Table 2 shows the distribution of
Figure 15. Types of equipment involved in the accidents and their frequencies.
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Figure 16. Types of equipment involved in the on-site accidents and their frequencies.
Figure 17. Types of equipment involved in the accidents at manufacturing plants and their frequencies.
Figure 18. End-use of buildings involved in the modular/prefabricated accidents and their frequencies.
the accidents by the states where they occurred. Since there is a lack of statistical data in the modular/prefabricated construction sector, e.g. the status of each state in this sector in terms of value and labours, the results cannot be generalized beyond the scope of this study. Locations of the accidents in terms of them being onsite or off-site were also examined. Approximately 62% of the accidents occurred on construction sites and 18% occurred at manufacturing plants. The location was not clearly identified for 20% of the accidents. In general, it can be concluded that on-site working environments pose greater safety risks than off-site construction operations. Safety can be expected to improve by fabricating as many components as possible in manufacturing plants.
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Figure 19. Activity performed at the time of accidents.
Discussion and conclusion In the construction industry, safety has always been a challenge for contractors and owners; therefore, improving safety performance for construction projects should be among the top priorities of construction practitioners. Many construction studies have been conducted in recent decades to identify safety risks and improve safety performance in this industry. Modular/prefabricated building construction is the offsite fabrication of buildings and building components in manufacturing plants for the purpose of increasing quality, improving safety, reducing construction time, minimizing waste, and increasing energy efficiency. This research targeted safety performance in the modular/ Table 2. States frequencies.
where
accidents
happened
and
their
State
Frequency of accidents
State
Frequency of accidents
AZ CA CA CO CT FL GA IA IA IL IN MA MD MN MO NC
2.4% 32.0% 3.2% 4.0% 0.8% 3.2% 1.6% 1.6% 0.8% 4.8% 0.8% 2.4% 9.6% 1.6% 0.8% 4.8%
NE NH NJ NV NY OH OK OR PA SC SD TN TX UT VA WI
2.4% 0.8% 0.8% 1.6% 2.4% 3.2% 0.8% 0.8% 2.4% 0.8% 0.8% 0.8% 3.2% 0.8% 2.4% 1.6%
prefabricated industry with the aim of discovering unsafe practices, which need to be addressed to improve safety performance in this construction sector. This research found 125 accidents related to modular/ prefabricated building construction from the OSHA database entitled ‘Fatality and Catastrophe Investigation Summaries’. The OSHA database had some limitations for the purpose of this research. The description section of some accident reports did not contain essential pieces of information sought in this study; therefore, assessing all safety parameters based on the OSHA database was challenging. Despite this limitation, all accident reports were studied in detail to determine associated safety risks. It should be noted that all the results and conclusions are drawn based on the investigated accidents related to modular/prefabricated building construction; therefore, generalization of the results to the whole modular/prefabricated building construction needs further investigation. The results indicate that the most common cause of the accidents was ‘fall’. The second most common cause was ‘struck by object/equipment (non-vehicle)’. In the on-site job accidents, ‘fall’ and ‘struck by object/equipment (nonvehicle)’ accounted for 87% of the accidents, whereas, among accidents that occurred in manufacturing plants, ‘struck by object/equipment (non-vehicle)’ and ‘caught in equipment/object/material’ accounted for 59% of the accidents. ‘Collapse of structure’ was the result of approximately 22% of the accidents. The underlying causes of ‘collapse of structure’ include lack or deficient bracing, unstable structure connection, and unsupported structure. The highest rate of the falls is ‘fall from roof’ (34.5%) followed by ‘fall from structure other than roof’ (25.5%). This research also showed that the majority of the accidents occurred during installation processes. Based on the findings, the major hazard in modular/prefabricated building construction appears to be fall from roofs and other
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International Journal of Injury Control and Safety Promotion structures and struck by unsecured structures during the on-site installation processes. Support connections in this construction sector require special and innovative design and training. Innovative connection designs should be able to secure structures and prevent them from collapsing during lifting, storing, and permanent installation. In addition, in several accidents, falls happened because the fall protection system was connected to unsecured structures. It is worth mentioning that approximately 16% of the fall accidents were due to workers not wearing required fall protection systems; therefore, following basic safety procedures seems to still be a challenge in the construction industry. According to the appendix E of the OSHA standard 1926-subpart M, if employers are engaged in leading edges work or involved in precast concrete and residential construction projects and it can be demonstrated that using conventional fall protection systems is infeasible or using them creates more hazards, a fall protection plan should be developed specifically for the work underway. Since workers in modular/prefabricated construction engage in manufacturing and installation of massive and heavy components, a fall protection plan specific to this construction sector should be developed and followed. The findings of the research also showed that construction labourers and carpenters are exposed to higher safety risks compared to other reported occupations. Among the equipment involved in the accidents, forklifts and saws had the highest frequency rates. A high percentage of off-site accidents was due to contact with equipment/tool which is the result of unsecured and unguarded equipment/tool. Appropriate maintenance and upgrading equipment and tool in terms of safety is one of the key steps for improving safety performance at manufacturing plants. Based on the accidents, working under moving modular/ prefabricated components or around stand-in-place components is another hazardous condition. Precise job planning to clear the working area around and under moving components by non-essential workers is of a great importance. The OSHA standard 1926.705(k)(1): Safety Requirements For Lift-Slab Operations can be considered as a basic safety practice for moving modular/prefabricated components. According to the standard (C.F.R. 29, Part 1926), ‘no employee, except those essential to the jacking operation, shall be permitted in the building/structure while any jacking operation is taking place unless the building/structure has been reinforced sufficiently to ensure its integrity during erection. The phrase “reinforced sufficiently to ensure its integrity” used in this paragraph means that a registered professional engineer, independent of the engineer who designed and planned the lifting operation, has determined from the plans that if there is a loss of support at any jack location, that loss will be confined to that location and the structure as a whole will remain stable’.
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The results confirm that typical construction jobs at manufacturing plants are potentially safer than on-site operations, and the majority of the accidents occurred on site. Off-site construction can improve safety performance in various ways. Construction sites usually have very dense spaces requiring intensive coordination among different parties and trades. In addition, since each construction project is a new working and unfamiliar location for workers, new safety risks are involved that workers may not have been faced before. However, since in modular/ prefabricated building construction, complex assemblies and major jobs are performed on the ground or in the factory, the need to work from heights is significantly reduced. In addition, people working in factories know most of the safety risks involved due to known and stable work locations. Despite the potential benefits of modular/prefabricated building construction in terms of safety, this construction strategy can be challenging and risky in some cases, for example, during moving and installation of massive components especially in high-rise buildings. Hoisting, moving, and installation of heavy and large components in this sector are complicated and dangerous. Therefore, with the expected rapid growth of modular/prefabricated building construction market, safety standards and training programmes should be developed to meet the specific requirements of this sector and to make employees familiar with related job hazards.
Future research In summary, this study has provided a foundation of knowledge upon which to base future studies regarding unsafe practices in modular/prefabricated building construction in order to improve the safety performance of this construction sector. This study can be a basis for developing pro-active and innovative solutions to address the following problem areas: implementation of best practices for fall protection including secure connection of fall protection systems during on-site assembly of components, stabilizing and secure temporary connections of modular/prefabricated structures during their installation, securing modular/prefabricated loads during transportation, lifting and storing, securing the working environment around heavy and light equipment both on site and in the manufacturing plants, guarding structures’ openings and securing the working environment around them, developing safety standards and training program directly related to modular/prefabricated building construction.
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Disclosure statement No potential conflict of interest was reported by the authors.
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