a systematic literature review of current research on

Proc. CIB W099 Achieving Sustainable Construction Health and Safety, Lund, Sweden, 2-3 June 2014

A SYSTEMATIC LITERATURE REVIEW OF CURRENT RESEARCH ON PREVENTION AND PROTECTION OF FALL FROM HEIGHT Lili Poon, Yang Miang Goh91, and Zhipeng Zhou Department of Building, School of Design and Environment, National University of Singapore, 119260, Singapore Prevention and mitigation of fall from height (FFH) has been researched in medical, human factors, engineering, psychology, and management disciplines. However, there is a tendency for these disciplines to be isolated and studies are typically narrowly scoped to address specific issues. This paper aims to systematically review fall from height academic research between 2003 and 2012, so as to compile useful findings for the construction industry and future research. A conceptual framework based on the Modified Loss Causation Model (MLCM) is developed to facilitate a holistic review of the current state of knowledge. An extensive search was conducted based on PubMed, Web of Knowledge (Web of Science) and ScienceDirect and 131 studies were selected for further analysis. The 131 papers were analyzed based on geographical location, industry sector, keywords and study type. It is observed that current research tend to focus on loss of balance and fall arrest systems. The key findings from the systematic literature review are summarized according to the conceptual framework and conflicting findings of different research are highlighted. Practical recommendations were provided for practitioners for improving the safety of work-at-height. Keywords: literature review, fall from height, modified loss causation model, fall arrest system

INTRODUCTION Work-at-height (WAH) is defined as “working in any place, including a place at or below ground level while at the same time including access and egress from such working place where a person could possibly fall a distance liable to cause personal injury” (Health and Safety Executive (HSE), 2013). As stated by the Workplace Safety and Health Council of Singapore (WSHC) (2011), a worker may be susceptible to risks of fall-from-height (FFH) while working at various types of platforms such as boom lifts, openings, excavation ditches, scaffolds, climbing work platforms, open sides and roofs. FFH accident has been a leading cause of injury in the construction industry in many regions including Singapore, New Zealand, Hong Kong, Taiwan, Kuwait, the United States (US), Israel and so forth (Tan, 2007; Bentley et al., 2006; Chan et al., 2008; Kartam et al., 1998; Lipscomb et al., 2004; Yanai et al., 1999). Not only do FFH accidents cause human suffering, substantial economic losses associated with fall injuries were also reported worldwide (Lockhart et al., 2005). In US, the 91

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annual direct cost of occupational injuries due to falls has been estimated to be in excess of 6 billion US dollars (Courtney et al., 2001). Due to the risk posed by FFH accident, many researchers around the world have been studying the problem of FFH. However, the large number of FFH publications made it hard for researchers and practitioners to have a clear overview of the current research. Although there were studies reviewing the FFH literature (Hsiao and Simeonov, 2001; Hsiao et al., 2008; Hu et al., 2011), these reviews were focused on specific topics. Hence, this study takes a holistic approach and aims to identify useful findings for the industry and propose possible improvements to the current safety guidelines and instructions.

METHODS Literature Search The academic databases, ScienceDirect, PubMed and Web of Knowledge were searched comprehensively. The search strategy used a combination of two sets of search terms connected using an “AND”. The terms in each set of search terms were combined using the “OR” connector. The first set of search terms comprised of eight terms (see Table 1) focusing on different situations or locations that FFH could possibly happen. The second set of search terms consisted of 42 key terms identified based on the framework provided by the Modified Loss Causation Model (MLCM) (Chua and Goh, 2004) (see Table 2). Furthermore, to ensure the recency of the results, the search was limited to articles published between 2003 and 2012. After merging the search results and removing duplicates, 1,078 studies remained. Table 1. Group one search terms used for literature research No.

Group one search terms

1

Falls from height(s)/ to lower level

2

Falls from elevation(s)/ elevated surface(s)/ elevated platform(s)

3

Falls through roof(s)/ inclined surface(s)

4

Falls through opening(s)/ hole(s)/ skylight(s)

5

Falls from formwork(s)/ provisional structure(s)

6

Falls from an open side

7

Falls from scaffold(s)

8

Fall from aerial lift(s)/ scissor lift(s)

Table 2. Group two search terms used for literature research No.

Group two search terms

1

Hazard(s)

2

Cause(s)/ causal factor(s)/contributing factor(s)

3

Risk(s)/fall risk(s)

4

Engineering control(s)/risk control measure(s)/ intervention(s)

5

Guardrail(s)/Handrail(s)

6

Accident prevention

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Proc. CIB W099 Achieving Sustainable Construction Health and Safety, Lund, Sweden, 2-3 June 2014 7

Personal protection equipment/personal protection system(s)

8

Fall arrest system(s)

9

Fall protection system(s)

10

Anchorage/anchor point

11

Energy absorber(s)/shock absorber(s)

12

Fall restraint

14

Lanyard

15

Lifeline(s)

16

Harness/body harness

17

Safety net(s)

18

Balance/imbalance/stability

19

Body control/postural control/postural sway

20

Slip(s)

21

Trip(s)

22

Worker’s behaviour(s)/safety behaviour(s)/unsafe behaviour(s)

23

Perception(s)/risk perception(s)

24

Training(s)/safety program

25

Work practice(s)/job practice(s)/on-site practice(s)

26

Safety culture/safety climate

27

Safety attitude

28

Regulation(s)/Occupational safety standard(s)

29

Supervision/inspection

30

Safety compliance

31

Hazard identification/audit(s)

32

Risk assessment

33

Safety management system(s)

34

Construction industry/building industry

35

Construction worker(s)/labourer(s)

36

Age

37

Fatigue

38

Experience

39

Management/ management commitment/management attitude

40

Motivation

41

Work pressure/stress/productivity pressure/time pressure

42

Co-worker(s)/workmate(s)/peer pressure

Literature Selection The relevance of the 1,078 articles was examined by screening the titles, keywords and abstracts. For articles where the information in the article title, keyword and 630


abstract was insufficient, the full text was reviewed. At this stage, 250 citations were classified as directly relevant and the full text articles of these articles were retrieved and further examined based on five additional criteria described below: 1. Context: Articles should be related to the construction industry. However, this does not mean that the data collected is construction specific. 2. Exposure: Articles related to fall-from-height accident in workplace setting were included while non-occupational fall was excluded. 3. Outcome: Articles focusing only on outcomes of FFH accidents including emergency response, injuries and day leave from work were excluded. 4. Language: Only articles in English were included. 5. Publication type: Only peer-reviewed journal articles were included. Book chapters, dissertations, and conference proceedings were excluded.

RESULTS Overview In total 131 publications met the selection criteria. The distribution of the year of publication is depicted in Fig.1. 20 18 16 14 12 10 8 6 4 2 0 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Fig.1. Year profile of literature publications

The 131 papers originated from eighteen different regions covering four continents. The distribution of the regions is illustrated in Table 3. Table 3. Geographical distribution Region

Australi a

Canad a

China

Denmark

Hong Kong

Israel

Japan

Korea

New Zealan d

Occurrenc e

5

5

4

2

7

3

1

2

1

Region

Poland

Spain

Swede n

Switzerlan d

Taiwa n

Thailan d

The Netherland s

United Kingdo m

United States

Occurrenc e

9

6

1

1

6

2

2

3

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Industry or sector studied Table 4 summarized the industry or sector studied in the articles. Twenty-six studies have taken a general approach to report data in a generic manner whereby such findings can be widely applicable to various aspects. Eight of the papers were focused on other industries, but they have findings directly relevant to the construction industry. The remaining papers were specific to the construction industry. 631


A larger fraction of papers (74 out of 131 papers) studied construction industry as a whole. While 20 papers studied residential construction sectors, signifying the risk of fall accident in the residential sector. Furthermore, roofing work appeared to be a key concern in the residential construction sector. It can be observed that there were fewer studies concerning commercial and civil sector and repair and maintenance. This suggests that sector-specific research especially in commercial and civil sectors may require more attention. Table 4. Industry and sector studied Industry or sector studied General Specific-Not construction industry Specific-Construction industry All sectors Residential sector (9 papers focus on roofing) Commercial and civil sector Repair and maintenance sector Total

Frequency 26 8 97 74 20 1 2 131

Study type Laboratory experiment was the most frequently used research method in the majority of papers reviewed. Most of the laboratory experiments were studying worker’s loss of balance and fall arrest systems (FAS). The summary of research methods for the selected papers is illustrated in Table 5. Table 5. Research methods Research type Frequency Analytical model based on empirical data 7 Archived data from government or research institutes database and compensation claims 17 Laboratory experiment 63 Interview and focus group 16 Survey and questionnaire 33 Site observation and audit 10 Total 146* *Note: The sum is not equal to total numbers of included papers as some papers may fall in more than one category.

Keywords analysis Keywords analysis is a useful tool for reflecting the topics of discussion. There were in total 860 keywords included in this analysis. After grouping the keywords with similar meanings and implications, 25 keywords with the highest repetitions are listed in Table 6. Table 6. The most frequently used keywords Classification Fall accident(s) Construction industry Sense of balance Occupational/construction safety and health Fall protective device/PPE Injury/injuries Manpower/worker(s) Prevention Human/human engineering

Frequency 68 58 54 49 48 31 26 26 21

Percentage 11.8% 10.1% 9.4% 8.5% 8.3% 5.4% 4.5% 4.5% 3.6%

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Proc. CIB W099 Achieving Sustainable Construction Health and Safety, Lund, Sweden, 2-3 June 2014 Slip(s) Equipment design/facility design Safety climate/safety culture Risk(s) Roof(s) Accident(s) Ladder safety Muscle fatigue Psychological issue Adult Male Behavioural issue Body factor Fatality/fatalities Regulation(s) Female

18 15 15 15 15 14 14 14 12 10 10 9 9 9 8 8

3.1% 2.6% 2.6% 2.6% 2.6% 2.4% 2.4% 2.4% 2.1% 1.7% 1.7% 1.6% 1.6% 1.6% 1.4% 1.4%

It is not surprising that ‘sense of balance’ (9.4%) is one of the most frequently cited keywords. ‘Fall protective device/ PPE’ (8.3%) also had a relatively high frequency. It is interesting to observe that 2.8% of the papers are focused on ‘equipment design/facility design’. This suggests a growing interest in reducing the risk of falls from height through improving current design. Safe engineering design is a preferred over fall protective devices, according to the hierarchy of control. The keyword analysis shows that ‘roof(s)’ (2.7%) and ‘ladder safety’ (2.6%) are key areas of research in FFH studies.

FURTHER ANALYSIS Analysis Framework The MLCM proposed by Chua and Goh (2004) was adapted to provide a framework to further categorise the 131 papers. The framework contains five main categories including situational variables, incident sequence, immediate causes, safety management system (SMS) failures and underlying factors. The focus areas and findings of the 131 papers were then classified in accordance to the framework to profile the distribution of current research in FFH. The first category is the situational variables, which identifies the critical characteristics of the work context in which FFH accident can occur. Some examples of situational variables include work executed on elevated surfaces, openings and skylights, floor slab formwork erection stage, roofs and roof trusses, low elevations, ladders and scaffolds. The second category examines the sequence of events in a FFH accident. The breakdown event, which typically takes place when a worker loses his/her balance at height. Worker’s loss of balance can be a result of various factors such as poor manual handling method, working posture, footwear, inclination of work surface, other worksite conditions, improper usage of PPE and so forth. After the breakdown event, pre-contact measures (prior to worker impacting a surface or object) should be in place to inhibit or minimize injuries after a fall has been initiated. Such measures mainly include fall arrest system (FAS). Due to time constraint of this review, other events in a typical FFH incident sequence (in accordance to the MLCM), including contact event, post-contact measures and consequences, were not included in this study. 633


The third category, immediate causes, consists of two components. The first component refers to unsafe behaviour of workers, such as failure to wear PPE. The second component involves personal factors leading to unsafe acts. Personal factors include, for instance, safety attitude and previous accident involvement, risk perception, experience, motivation and so forth. The forth category refers to a lack of measures or inadequate measures in SMS. For instance, inadequate safety management, risk assessment and hazard audits, insufficient provision of PPE and training. The fifth category, underlying factor, comprises of two components, namely job factors and organizational factors, respectively. Job factors refer to factors related to task definition and execution. For instance, supervision and inspection, task nature, project attributes and legal enforcement. On the other hand, organizational factors are recognized to have effects in influencing organization’s SMS. Such factors comprise of firm size, work pressure, management commitment to safety climate and so forth. It is noted that personal factors and underlying factors are usually not industry-specific and research findings can potentially apply across industries. Discussion The 131 papers were classified into the different categories of the framework based on their overall objectives and key findings. Some studies may be classified into more than one category, depending on the nature of the research finding. According to Fig.2, ‘incident sequence’ has distinguished itself to be the category with the highest percentage (28%). This is because this category includes prevention measures, worker’s loss of balance and pre-contact measures, which are commonly discussed in the literature. ‘Underlying factors’ (26%) and ‘immediate cause’ (20%) also have relatively high frequency. Category 1: Situational Cateogry 5: variables 12% Underlying factors 26%

Category 2: Incident Category 4: sequence SMS 28% failures Category 3: Immediate 14% cause 20% Fig.2. Categories of publications based on MLCM

Table 7 shows the distribution in greater detail. In the category of ‘incident sequence’, 39 studies were about loss of balance. As argued by Hsiao and Simeonov (2001), most occupational falls are commonly initiated by imbalance, slips and trips. Thus, the relatively large number of papers is justifiable. The 39 papers determined various factors affecting balance of workers including working environment, work execution, physiological issue and psychological factor. The review found that current research 634


has generally shown a relatively comprehensive picture for the factors related to balance issue. However, it was observed that prevention measures did not receive much attention in the studies reviewed. Although guardrails were frequently discussed, the number of such publications remained significantly low. Additional research efforts should be given to these prevention measures (or engineering controls). Ironically, despite engineering controls being acknowledged as a more effective and sustainable form of risk control, there were significantly more research on use of PPE to reduce risk of FFH accidents. Among the studies on PPE, fall arrest system (FAS) appears to be the main area of focus, possibly due to the heavy reliance on FAS on worksites. Table 7. Detailed breakdown of literature according to framework findings Framework topic Category 1: Situational variables Openings and skylights Floor slab formwork erection stage Roofs Low elevations Scaffolds Ladders Category 2: Incident sequence Component 2a. Prevention measures General approach: active measures for various situations Guardrails Component 2b. Breakdown event – Worker’s loss of balance Heights simulation/ Virtual height effects Worksite conditions Sensory and visual interaction Effects of inclination Physique and sex Psychological effect: perception of height Localized muscle fatigue and role of ankle Load handling Posture and foot placement Workload and duration Footwear effects Influences of Personal Protective Equipment (PPE) Component 2c. Pre-contact measures Fall arrest system (FAS) Safety nets Hands Category 3: Immediate cause Component 3a. Unsafe behaviours Failures to use PPE Component 3b. Personal factors leading to unsafe behaviours Safety attitude and previous accident involvement Risk perception Working Experience Age Motivation Drinking habit Language ability and cultural factor Self-esteem Category 4: SMS failures Component 4a. Lack of measures or inadequate measures

Frequency 35 7 3 4 4 7 10 65 4 2 2 39* 4 9 5 4 2 2 6 7 3 7 2 2 22 20 1 1 40 5 5 35* 7 11 15 6 3 3 3 3 33 33*

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Proc. CIB W099 Achieving Sustainable Construction Health and Safety, Lund, Sweden, 2-3 June 2014 SMS 5 Risk assessment and fall hazard audits 9 Training 22 Provisions of PPE 3 Category 5: Underlying factors 48 Component 5a. Job factors 17* Task nature 4 Project attributes 4 Legal enforcement 6 Supervision and inspection 4 Component 5b. Organizational factors 31* Firm size 5 Co-worker’s influences 7 Work pressure 12 Job communication 10 Management’s commitment to safety climate 18 *Note: The sum is not equal to total numbers of included papers, as some papers may fall in more than one category.

Among the various immediate causes, working experience is the most frequently mentioned factor. Consistent with previous research (Hu et al., 2011), the second frequently discussed factor is risk perception of workers. It is noted that Larsson et al. (2008) highlighted motivation as a key mediator which can influence safety behaviour direct and indirectly. For instance, despite the provision of equipment and adequate training, workers continue to engage in unsafe behaviours due low motivation (Kines, 2003). It is reasonable to argue that the key to safety behaviours of workers largely lies in workers’ motivation. As there are relatively few publications on motivation of safety behaviours in the construction industry, it is an area of worthy of further research. In terms of safety management, there are a considerable number of publications focusing on training provided to workers. The significance of training and its effectiveness were also reinforced in previous literature (Chan et al., 2008; Fang et al., 2006; Huang and Hinze, 2003; Martin et al., 2009; Sa et al., 2009). In the category of underlying factors, it was observed that job factors received relatively less emphasis compared to organizational factors. On the other hand, among the contributing factors in organizational factors, management commitment to safety climate was the main emphasis. This finding is consistent with previous literature that a management commitment to safety produces safer on-site behaviours (Fung et al., 2005; Larsson et al., 2008; Mohamed et al., 2009). Recommendations Training Previous studies indicated a common problem that training curriculum fails to meet the need of workers due to its discrepancies with onsite practices (Lipscomb et al., 2008; Kaskutas et al., 2012). Thus, there is a need to evaluate the effectiveness of WAH training in improving safety behavior of workers working at height. Besides training courses, other forms of training, such as coaching by experienced workers (Kines et al., 2010; Hung et al., 2012) should be developed. Besides training workers on WAH knowledge and skills, there is also a need to ensure that construction foremen have the ability to communicate safety messages related to WAH effectively (Kaskutas et al., 2012). Furthermore, it is interesting to note that 636


workers’ perception about the importance of safety training may also be used as an indicator of actual levels of safety behaviour (Cooper and Phillips, 2004). Potential improvements on safety guidelines Governments or agencies of different countries have collaborated to improve FFH problem by developing a number of guidelines and toolkits for industry. These guidelines include a wide range of topics such as design for safety, fall protection plan, risk management, risk control measures, inspection and maintenance, training and supervision, and good practices for working at various elevated surfaces such as roofs and ladders. There are also some toolkits such as WAH checklist and planning tool provided for industry players to evaluate their worksite safety compliance and to recommend improvements required. It is seen that the construction industry has been focusing on the technical aspects of fall protection measures. However, it is observed that the industry demonstrates insufficient efforts to address worker’s loss of balance despite significant research in this area. Useful findings regarding sense of balance from current research were seldom utilized by the industry to prevent falls from height. As falls are common to be initiated by imbalance, slips and trips conditions, industry should provide guidelines to enhance worker’s balance at work. Industry may also contemplate improving work environment by establishing better housekeeping policy, developing good practices for posture, foot placement and load handling, setting appropriate work-rest cycles, selecting proper footwear designs and building visual cue for stabilizing effects to improve WAH safety. New technology and design The current literature has demonstrated a trend to enhance safety through improving workplace design. This is a promising research agenda and future research should aim to develop innovative technology to help to reduce workers exposure to WAH hazards.

CONCLUSIONS FFH accident is a persistent problem in the construction industry, and it has contributed to a high percentage of fatality. In order to provide an overview of the current research in the area of FFH, this study systematically reviewed the relevant literature the past 10 years. In addition, a conceptual framework based on an accident causation model is also used to understand the distribution of the current research. Recommendations involving in training, safety guidelines, and new technology and design, were proposed for improving FFH issue in construction industry. It is believed that further research and improvements to these aspects not only helps to save workers from suffering from FFH injuries but also prevent substantial economic losses associated with falls.

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