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A better understanding of circumstances contributing to the severity outcome of traffic crashes is an important goal of road safety studies. An in-depth crash injury severity analysis is vital for the proactive implementation of appropriate mitigation strategies. This study proposes an improved feed-forward neural network (FFNN) model for predicting injury severity associated with individual crashes using three years (2017–2019) of crash data collected along 15 rural highways in the Kingdom of Saudi Arabia (KSA). A total of 12,566 crashes were recorded during the study period with a binary injury severity outcome (fatal or non-fatal injury) for the variable to be predicted. FFNN architecture with back-propagation (BP) as a training algorithm, logistic as activation function, and six number of hidden neurons in the hidden layer yielded the best model performance. Results of model prediction for the test data were analyzed using different evaluation metrics such as overall accuracy, sensitivity, and specificity. Prediction results showed the adequacy and robust performance of the proposed method. A detailed sensitivity analysis of the optimized NN was also performed to show the impact and relative influence of different predictor variables on resulting crash injury severity. The sensitivity analysis results indicated that factors such as traffic volume, average travel speeds, weather conditions, on-site damage conditions, road and vehicle type, and involvement of pedestrians are the most sensitive variables. The methods applied in this study could be used in big data analysis of crash data, which can serve as a rapid-useful tool for policymakers to improve highway safety.
Arshad Jamal; Waleed Umer. Exploring the Injury Severity Risk Factors in Fatal Crashes with Neural Network. International Journal of Environmental Research and Public Health 2020, 17, 7466 .
AMA StyleArshad Jamal, Waleed Umer. Exploring the Injury Severity Risk Factors in Fatal Crashes with Neural Network. International Journal of Environmental Research and Public Health. 2020; 17 (20):7466.
Chicago/Turabian StyleArshad Jamal; Waleed Umer. 2020. "Exploring the Injury Severity Risk Factors in Fatal Crashes with Neural Network." International Journal of Environmental Research and Public Health 17, no. 20: 7466.
Cardiorespiratory (e.g., heart rate and breathing rate) and thermoregulatory (e.g., local skin temperature and electrodermal activity) responses are controlled by the sympathetic nervous system. To cope with increased physical workload, the sympathetic system upregulates its activity to generate greater sympathetic responses (i.e., increased heart rate and respiratory rate). Therefore, physiological measures may have the potential to evaluate changes in physical condition (including fatigue) during functional tasks. This study aimed to quantify physical fatigue using wearable cardiorespiratory and thermoregulatory sensors during a simulated construction task. Twenty-five healthy individuals (mean age, 31.8 ± 1.8 years) were recruited. Participants were instructed to perform 30 min of a simulated manual material handling task in a laboratory. The experimental setup comprised a station A, a 10-metre walking platform, and a station B. Each participant was asked to pick up a 15 kg ergonomically-designed wooden box from station A and then carried it along the platform and dropped it at station B. The task was repeated from B to A and then A to B until the participants perceived a fatigue level > 15 out of 20 on the Borg-20 scale. Heart rate, breathing rate, local skin temperature, and electrodermal activity at the wrist were measured by wearable sensors and the perceived physical fatigue was assessed using the Borg-20 scale at baseline, 15 min, and 30 min from the baseline. There were significant increases in the heart rate (mean changes: 50 ± 13.3 beats/min), breathing rate (mean changes: 9.8 ± 4.1 breaths), local skin temperature (mean changes: 3.4 ± 1.9 °C), electrodermal activity at the right wrist (mean changes: 7.1 ± 3.8 µS/cm), and subjective physical fatigue (mean changes: 8.8 ± 0.6 levels) at the end of the simulated construction task (p < 0.05). Heart rate and breathing rate at 15 and 30 min were significantly correlated with the corresponding subjective Borg scores (p < 0.01). Local skin temperature at 30 min was significantly correlated with the corresponding Borg scores (p < 0.05). However, electrodermal activity at the right wrist was not associated with Borg scores at any time points. The results implied cardiorespiratory parameters and local skin temperature were good surrogates for measuring physical fatigue. Conversely, electrodermal activity at the right wrist was unrelated to physical fatigue. Future field studies should investigate the sensitivity of various cardiorespiratory and thermoregulatory parameters for real time physical fatigue monitoring in construction sites.
Shahnawaz Anwer; Heng Li; Maxwell Antwi-Afari; Waleed Umer; Arnold Wong. Cardiorespiratory and Thermoregulatory Parameters Are Good Surrogates for Measuring Physical Fatigue during a Simulated Construction Task. International Journal of Environmental Research and Public Health 2020, 17, 5418 .
AMA StyleShahnawaz Anwer, Heng Li, Maxwell Antwi-Afari, Waleed Umer, Arnold Wong. Cardiorespiratory and Thermoregulatory Parameters Are Good Surrogates for Measuring Physical Fatigue during a Simulated Construction Task. International Journal of Environmental Research and Public Health. 2020; 17 (15):5418.
Chicago/Turabian StyleShahnawaz Anwer; Heng Li; Maxwell Antwi-Afari; Waleed Umer; Arnold Wong. 2020. "Cardiorespiratory and Thermoregulatory Parameters Are Good Surrogates for Measuring Physical Fatigue during a Simulated Construction Task." International Journal of Environmental Research and Public Health 17, no. 15: 5418.
Overexertion-related construction activities are identified as a leading cause of work-related musculoskeletal disorders (WMSDs) among construction workers. However, few studies have focused on the automated recognition of overexertion-related construction workers’ activities as well as assessing ergonomic risk levels, which may help to minimize WMSDs. Therefore, this study examined the feasibility of using acceleration and foot plantar pressure distribution data captured by a wearable insole pressure system for automated recognition of overexertion-related construction workers’ activities and for assessing ergonomic risk levels. The proposed approach was tested by simulating overexertion-related construction activities in a laboratory setting. The classification accuracy of five types of supervised machine learning classifiers was evaluated with different window sizes to investigate classification performance and further estimate physical intensity, activity duration, and frequency information. Cross-validation results showed that the Random Forest classifier with a 2.56-s window size achieved the best classification accuracy of 98.3% and a sensitivity of more than 95.8% for each category of activities using the best features of combined data set. Furthermore, the estimation of corresponding ergonomic risk levels was within the same level of risk. The findings may help to develop a noninvasive wearable insole pressure system for the continuous monitoring and automated activity recognition, which could assist researchers and safety managers in identifying and assessing overexertion-related construction activities for minimizing the development of WMSDs’ risks among construction workers.
Maxwell Fordjour Antwi-Afari; Heng Li; Waleed Umer; Yantao Yu; Xuejiao Xing. Construction Activity Recognition and Ergonomic Risk Assessment Using a Wearable Insole Pressure System. Journal of Construction Engineering and Management 2020, 146, 04020077 .
AMA StyleMaxwell Fordjour Antwi-Afari, Heng Li, Waleed Umer, Yantao Yu, Xuejiao Xing. Construction Activity Recognition and Ergonomic Risk Assessment Using a Wearable Insole Pressure System. Journal of Construction Engineering and Management. 2020; 146 (7):04020077.
Chicago/Turabian StyleMaxwell Fordjour Antwi-Afari; Heng Li; Waleed Umer; Yantao Yu; Xuejiao Xing. 2020. "Construction Activity Recognition and Ergonomic Risk Assessment Using a Wearable Insole Pressure System." Journal of Construction Engineering and Management 146, no. 7: 04020077.
Ultra wide band (UWB)-based real-time location systems (RTLSs) have been widely adopted in the manufacturing industry for tracking tools, materials, and ensuring safety. Researchers in the construction domain have investigated similar uses for UWB-based RTLSs on construction jobsites. However, most of these investigations comprised small-scale experiments using average accuracy only to demonstrate use cases for the technology. Furthermore, they did not consider alternative deployment scenarios for practically feasible deployment of the technology. To overcome these limitations, a series of experiments were performed to study the feasibility of a commercially available RTLS on the construction jobsites. The focus of the work was on feasibility in terms of accuracy analysis of the system for a large experimental site, the level of effort requirements for deployment, and the impact of deployment alternatives on the accuracy of the system. The results found that average accuracy was found to be a misleading indicator of the perceived system performance (i.e., 95th percentile values were considerably higher than average values). Moreover, accuracy is significantly affected by the deployment alternatives. Collectively, the results arising from the study could help construction/safety managers in decision making related to the deployment of UWB-based RTLSs for their construction sites.
Waleed Umer; Mohsin K. Siddiqui. Use of Ultra Wide Band Real-Time Location System on Construction Jobsites: Feasibility Study and Deployment Alternatives. International Journal of Environmental Research and Public Health 2020, 17, 2219 .
AMA StyleWaleed Umer, Mohsin K. Siddiqui. Use of Ultra Wide Band Real-Time Location System on Construction Jobsites: Feasibility Study and Deployment Alternatives. International Journal of Environmental Research and Public Health. 2020; 17 (7):2219.
Chicago/Turabian StyleWaleed Umer; Mohsin K. Siddiqui. 2020. "Use of Ultra Wide Band Real-Time Location System on Construction Jobsites: Feasibility Study and Deployment Alternatives." International Journal of Environmental Research and Public Health 17, no. 7: 2219.
Physical exertion led fatigue is a serious threat to occupational health and safety of construction workers worldwide. Its acute effects include a decrease in cognitive abilities, productivity and heightened risk of accidents whereas prolonged physical exertion led fatigue could lead to psychological issues and development of musculoskeletal disorders. To monitor physical exertion, traditionally questionnaires have been used while recent advances have focused on onsite and on-body sensors to automate the process. Considering the limitation of the recent approaches, this study explored the use of combined cardiorespiratory and thermoregulatory measures to model physical exertion using machine learning algorithms. Controlled manual material handling experiments were conducted during a preliminary study to induce exertion at a steady rate involving ten participants. The results revealed that the proposed methodology could predict exertion levels with a high accuracy of 95.3% for combined data modeling of all participants. However, for some predictions, the error between predicted and actual exertion was up to five levels on the Borg-20 scale. To mitigate this issue, individualized machine learning models were used that effectively reduced the maximum error to one level with an average accuracy of 96.7% while using only one-tenth of the total data set. Overall, this study highlights the advantage of using multiple physiological measures for enhancing physical exertion modeling. Notably, the study underpins the use of individualized models for exertion monitoring and management to prevent physical fatigue development and its ill effects.
Waleed Umer; Heng Li; Yu Yantao; Maxwell Fordjour Antwi-Afari; Shahnawaz Anwer; Xiaochun Luo. Physical exertion modeling for construction tasks using combined cardiorespiratory and thermoregulatory measures. Automation in Construction 2020, 112, 103079 .
AMA StyleWaleed Umer, Heng Li, Yu Yantao, Maxwell Fordjour Antwi-Afari, Shahnawaz Anwer, Xiaochun Luo. Physical exertion modeling for construction tasks using combined cardiorespiratory and thermoregulatory measures. Automation in Construction. 2020; 112 ():103079.
Chicago/Turabian StyleWaleed Umer; Heng Li; Yu Yantao; Maxwell Fordjour Antwi-Afari; Shahnawaz Anwer; Xiaochun Luo. 2020. "Physical exertion modeling for construction tasks using combined cardiorespiratory and thermoregulatory measures." Automation in Construction 112, no. : 103079.
Construction equipment related accidents, such as collisions between equipment and pedestrian workers, pose a major challenge to occupational safety at construction sites. Decrement of operators' hazard detection ability resulting from attention failure is a leading cause of these accidents. Although mental fatigue induced by prolonged and monotonous operating tasks is known as the primary cause of this type of failure, little is revealed on how mental fatigue influences operators' ability to detect hazardous situations and associated visual attention features. To address this issue, this study uses wearable eye-tracking technology to evaluate the impact of mental fatigue on operators' ability in hazard detection and the corresponding patterns of visual attention allocation. Twelve healthy participants performed a simulated excavator operating task in a laboratory experiment. Subjective mental fatigue assessment, hazard detection task performance, and eye movement metrics were recorded and analyzed. In the experiment, mental fatigue was effectively induced and manipulated by a Time-On-Operating (TOO) procedure. Results revealed that operators' hazard detection ability decreased with the increase in subjective mental fatigue level, reflected by significant increases in reaction time for hazards and the number of misdetections. Attention allocation-related data were further analyzed to explain the specific manifestations of hazard detection failure in visual attention. The results indicated that the decrease of operators' hazard detection ability is associated with the changes of the distributions of fixation and gaze point while mental fatigue level increases. Consequently, clear observation of surrounding hazards and related details becomes difficult for operators. The findings demonstrate the effectiveness of wearable eye-tracking technology in measuring and quantifying operators' mental fatigue and hazard detection ability. More importantly, the findings offer insights into the impairing effect of mental fatigue on operators' hazard detection ability from a visual attention perspective. Such insights provide a solid basis for developing effective safety interventions and attentional guidance-based safety training methods to mitigate relevant site accidents.
Jue Li; Heng Li; Hongwei Wang; Waleed Umer; Hong Fu; Xuejiao Xing. Evaluating the impact of mental fatigue on construction equipment operators' ability to detect hazards using wearable eye-tracking technology. Automation in Construction 2019, 105, 102835 .
AMA StyleJue Li, Heng Li, Hongwei Wang, Waleed Umer, Hong Fu, Xuejiao Xing. Evaluating the impact of mental fatigue on construction equipment operators' ability to detect hazards using wearable eye-tracking technology. Automation in Construction. 2019; 105 ():102835.
Chicago/Turabian StyleJue Li; Heng Li; Hongwei Wang; Waleed Umer; Hong Fu; Xuejiao Xing. 2019. "Evaluating the impact of mental fatigue on construction equipment operators' ability to detect hazards using wearable eye-tracking technology." Automation in Construction 105, no. : 102835.
The construction industry around the globe is afflicted with an exorbitant rate of fatal and non-fatal falls. To lower the propensity of the falls, researchers and safety experts have recommended to supplement the traditional passive fall safety measures with some active measures (such as early identification of task/environmental hazards and personal risk factors). Unfortunately, at present, there is no readily available onsite tool which could identify workers with poor postural controls. This study aimed to develop a static balance monitoring tool for proactive tracking of construction workers on-site using a wearable inertial measurement unit (WIMU) and a smartphone. To this end, a three-phase project was conducted. Firstly, a validation study was conducted to examine the validity of using WIMUs to detect task/fatigue-induced changes in static balance during a 20-second static balance test. The results of the study revealed that WIMUs could detect the post-task subtle changes in static balance with reference to the findings of a force-plate (considered as industrial standard). Secondly, since there were no existing static balance classification methods, five experts were engaged to establish balance classification thresholds using the fuzzy set theory. Thirdly, a mobile phone application was developed for the managers/foremen for onsite balance monitoring of the construction workers using the 20-second test at different times of the day and establishing their corresponding balance performance profiles. This would assist early identification of fall prone workers, plan mitigation schemes before a fall accident happens and ultimately help reduce falls in the construction industry.
Waleed Umer; Heng Li; Wei Lu; Grace Pui Yuk Szeto; Arnold Y.L. Wong. Development of a tool to monitor static balance of construction workers for proactive fall safety management. Automation in Construction 2018, 94, 438 -448.
AMA StyleWaleed Umer, Heng Li, Wei Lu, Grace Pui Yuk Szeto, Arnold Y.L. Wong. Development of a tool to monitor static balance of construction workers for proactive fall safety management. Automation in Construction. 2018; 94 ():438-448.
Chicago/Turabian StyleWaleed Umer; Heng Li; Wei Lu; Grace Pui Yuk Szeto; Arnold Y.L. Wong. 2018. "Development of a tool to monitor static balance of construction workers for proactive fall safety management." Automation in Construction 94, no. : 438-448.
I.A.A.R.C. - International Association for Automation and Robotics in Construction Civil Engineering
Yantao Yu; Heng Li; Xincong Yang; Xincong Yang And Waleed Umer. Estimating Construction Workers' Physical Workload by Fusing Computer Vision and Smart Insole Technologies. Proceedings of the 35th International Symposium on Automation and Robotics in Construction (ISARC) 2018, 1212 -1219.
AMA StyleYantao Yu, Heng Li, Xincong Yang, Xincong Yang And Waleed Umer. Estimating Construction Workers' Physical Workload by Fusing Computer Vision and Smart Insole Technologies. Proceedings of the 35th International Symposium on Automation and Robotics in Construction (ISARC). 2018; ():1212-1219.
Chicago/Turabian StyleYantao Yu; Heng Li; Xincong Yang; Xincong Yang And Waleed Umer. 2018. "Estimating Construction Workers' Physical Workload by Fusing Computer Vision and Smart Insole Technologies." Proceedings of the 35th International Symposium on Automation and Robotics in Construction (ISARC) , no. : 1212-1219.
Fall accidents (FAs) constitute a substantial proportion of construction accidents. While the predominant prevention strategy relies on passive approaches (e.g., guardrails), research on proactive measures is lacking, which may reduce the incidence of FAs in high-risk construction trades. Literature suggests that rebar work is one of the foremost FA-prone construction trades. Since rebar workers spend hours in rebar tying postures with periodic postural transitions, they hypothetically are at risk of posttask loss of balance. While recent research showed that a sitting stool could significantly alleviate physical discomfort during rebar tying, the current study aimed to investigate temporal changes in standing balance (using a force plate) after simulated rebar tying in squatting, stooping, and stool-sitting while the respective postural load during rebar tying was quantified by electromyography and oximeters. Results demonstrated that stool-sitting resulted significantly better posttask standing balance than squatting or stooping, which might be attributed to differential postural loadings. Overall, the findings reported herein underpin the importance of using safety informatics to proactively analyze task-specific fall hazards, to monitor workers’ balance, and to implement proper prevention strategies for workers at risk of falls.
Waleed Umer; Heng Li; Grace Pui Yuk Szeto; Arnold Y. L. Wong. Proactive Safety Measures: Quantifying the Upright Standing Stability after Sustained Rebar Tying Postures. Journal of Construction Engineering and Management 2018, 144, 04018010 .
AMA StyleWaleed Umer, Heng Li, Grace Pui Yuk Szeto, Arnold Y. L. Wong. Proactive Safety Measures: Quantifying the Upright Standing Stability after Sustained Rebar Tying Postures. Journal of Construction Engineering and Management. 2018; 144 (4):04018010.
Chicago/Turabian StyleWaleed Umer; Heng Li; Grace Pui Yuk Szeto; Arnold Y. L. Wong. 2018. "Proactive Safety Measures: Quantifying the Upright Standing Stability after Sustained Rebar Tying Postures." Journal of Construction Engineering and Management 144, no. 4: 04018010.
Although individual studies have reported high prevalence of musculoskeletal symptoms (MSS) among construction workers, no systematic review has summarized their prevalence rates. Accordingly, this systematic review/meta-analysis aimed to synthesize MSS prevalence in different construction trades, gender and age groups, which may help develop specific ergonomic interventions. Nine databases were searched for articles related to the research objective. Two reviewers independently screened citations, extracted information and conducted quality assessment of the included studies. Meta-analyses were conducted on clinical and statistical homogenous data. Thirty-five out of 1130 potential citations were included reporting diverse types of period prevalence and case definitions. Only the 1-year prevalence rates of MSS (defined as at least one episode of pain/MSS in the last year) at nine anatomical regions had sufficient homogeneous data for meta-analysis. Specifically, the 1-year prevalence of MSS was 51.1% for lower back, 37.2% for knee, 32.4% for shoulder, 30.4% for wrist, 24.4% for neck, 24.0% for ankle/foot, 20.3% for elbow, 19.8% for upper back, and 15.1% for hip/thigh. Female workers demonstrated a higher prevalence of MSS while there was insufficient information on the prevalence of trade-specific or age-related MSS. The quality assessments revealed that many included studies estimated prevalence solely based on self-reported data, and did not report non-respondents’ characteristics. Lumbar, knee, shoulder, and wrist MSS are the most common symptoms among construction workers. Future studies should standardize the reporting of period prevalence of MSS in different construction trades to allow meta-analyses and to develop relevant MSS prevention program.
Waleed Umer; Maxwell F. Antwi-Afari; Heng Li; Grace Szeto; Arnold Y. L. Wong. The prevalence of musculoskeletal symptoms in the construction industry: a systematic review and meta-analysis. International Archives of Occupational and Environmental Health 2017, 91, 125 -144.
AMA StyleWaleed Umer, Maxwell F. Antwi-Afari, Heng Li, Grace Szeto, Arnold Y. L. Wong. The prevalence of musculoskeletal symptoms in the construction industry: a systematic review and meta-analysis. International Archives of Occupational and Environmental Health. 2017; 91 (2):125-144.
Chicago/Turabian StyleWaleed Umer; Maxwell F. Antwi-Afari; Heng Li; Grace Szeto; Arnold Y. L. Wong. 2017. "The prevalence of musculoskeletal symptoms in the construction industry: a systematic review and meta-analysis." International Archives of Occupational and Environmental Health 91, no. 2: 125-144.
The construction industry around the globe is facing a massive predicament of work-related musculoskeletal disorders (MSDs), largely attributed to the excessive physical exertion at worksites. Whereas ergonomic interventions are suggested to be an effective approach to mitigate such routine exertion, these ergonomic interventions should be task specific because of the unique characteristics of each trade (such as rebar work; a construction trade with a high prevalence rate of MSDs). Despite numerous potential interventions available for rebar workers, none of them has been widely adopted, especially in the Asian market. After considering various reasons impeding their broad usage, the authors coined a simple ergonomic solution by attaching a low height domestic stool to the pants of rebar workers. This would allow them to sit and work instead of squatting, which is the most preferred posture in Asian cultures for working at ground level. The novel intervention was tested against squatting for various physical outcomes (i.e., muscle activity, neuromuscular fatigue, trunk kinematics and lower extremity blood circulation) and self-perceived discomfort, using a simulated rebar tying task in a laboratory. These findings demonstrate that the intervention has beneficial effects on both physical and subjective outcomes, and has a great potential in reducing work-related MSDs among Asian rebar workers. Additionally, the current study highlights that ergonomic interventions in the construction industry should be derived based on both the characteristics of specific construction trades and culture of workers.
Waleed Umer; Heng Li; Grace Pui Yuk Szeto; Arnold Y. L. Wong. Low-Cost Ergonomic Intervention for Mitigating Physical and Subjective Discomfort during Manual Rebar Tying. Journal of Construction Engineering and Management 2017, 143, 04017075 .
AMA StyleWaleed Umer, Heng Li, Grace Pui Yuk Szeto, Arnold Y. L. Wong. Low-Cost Ergonomic Intervention for Mitigating Physical and Subjective Discomfort during Manual Rebar Tying. Journal of Construction Engineering and Management. 2017; 143 (10):04017075.
Chicago/Turabian StyleWaleed Umer; Heng Li; Grace Pui Yuk Szeto; Arnold Y. L. Wong. 2017. "Low-Cost Ergonomic Intervention for Mitigating Physical and Subjective Discomfort during Manual Rebar Tying." Journal of Construction Engineering and Management 143, no. 10: 04017075.
High prevalence of musculoskeletal disorders among construction workers pose challenges to the productivity and occupational health of the construction industry. To mitigate the risk of musculoskeletal disorders, construction managers need to deepen their understanding of the physical and biomechanical demands of various construction tasks so that appropriate policies and preventive measures can be implemented. Among various construction trades, rebar workers are highly susceptible to lower-back disorders (LBDs) given the physically demanding nature of their work tasks. In particular, rebar tying is considered to be closely related to LBDs because it exposes workers to multiple ergonomic risk factors (repetitive works in prolonged static and awkward postures). The objective of the current study was to compare the differences in lumbar biomechanics during three typical rebar tying postures: stooping, one-legged kneeling, and squatting. Biomechanical variables including trunk muscle activity and trunk kinematics were measured by surface electromyography and motion sensors, respectively. Ten healthy male participants performed a simulated rebar tying task in each of the three postures in a laboratory setting. Repeated measures analysis of variance showed that while each posture has its unique trunk kinematic characteristics, all these postures involved excessive trunk inclination that exceeded the internationally recommended trunk inclination angle of 60° for static working postures. Of the three postures, stooping posture demonstrated a significant reduction in electromyographic activity of lumbar muscles (a reduction in 60–80% of muscle activity as compared to the other two postures). The reduced muscle activity may shift the loading to passive spinal structures (e.g., spinal ligaments and joint capsules), which is known to be a risk factor for LBD development. Collectively, the results from this study may help explain the high prevalence of LBDs in rebar workers. Future studies are warranted to confirm the findings at construction sites and to develop appropriate ergonomic approaches for rebar workers.
Waleed Umer; Heng Li; Ph.D. Grace Pui Yuk Szeto; Ph.D. Arnold Yu Lok Wong. Identification of Biomechanical Risk Factors for the Development of Lower-Back Disorders during Manual Rebar Tying. Journal of Construction Engineering and Management 2017, 143, 04016080 .
AMA StyleWaleed Umer, Heng Li, Ph.D. Grace Pui Yuk Szeto, Ph.D. Arnold Yu Lok Wong. Identification of Biomechanical Risk Factors for the Development of Lower-Back Disorders during Manual Rebar Tying. Journal of Construction Engineering and Management. 2017; 143 (1):04016080.
Chicago/Turabian StyleWaleed Umer; Heng Li; Ph.D. Grace Pui Yuk Szeto; Ph.D. Arnold Yu Lok Wong. 2017. "Identification of Biomechanical Risk Factors for the Development of Lower-Back Disorders during Manual Rebar Tying." Journal of Construction Engineering and Management 143, no. 1: 04016080.