Risk of excavators overturning: determining horizontal centrifugal force when slewing freely suspended loads

Purpose: Tracked hydraulic excavators are versatile and ubiquitous items of off-highway plant and machinery that are utilised throughout the construction industry. Each year a significant number of excavators overturn whilst conducting a lifting operation, causing damage to property, personnel injury or even fatality. The reasons for the overturn are myriad, including: operational or environmental conditions; machine operator acts or omissions; and/ or inadequate site supervision. Furthermore, the safe working load (SWL) figure obtained from manufacturer guidance and utilised in lift plans is based upon undertaking a static load only. This research seeks to determine whether the SWL is still safe to be used in a lift plan when slewing a freely suspended (dynamic) load, and if not, whether this may be a further contributory factor to overturn incidents. Approach: Previous research has developed a number of machine stability test regimes but these were largely subjective, impractical to replicate and failed to accurately measure the ‘dynamic’ horizontal centrifugal force resulting from slewing the load. This research contributes towards resolving the stability problem by critically evaluating existing governing standards and legislation, investigating case studies of excavator overturn and simulating the dynamic effects of an excavator when slewing a freely suspended load at high rotations per minute (rpm). To achieve this, both the static load and horizontal centrifugal force from slewing this load were calculated for six randomly selected cases of an excavator, with different arm geometry configurations. Findings: The results from the six cases are presented and a worked example of one is detailed to demonstrate how the results were derived. The findings reveal that the SWL quoted on an excavator’s lift rating chart considerably underestimates the extra forces experienced by the machine when an additional dynamic load is added to the static load whilst lifting and slewing a freely suspended load. Originality: This work presents the first attempt to accurately model excavator stability by taking consideration of the dynamic forces caused by slewing a freely suspended load and will lead to changes in the way that industry develops and manages lift plans. Future research proposes to: vary the weight of load, arm geometry and rpm to predict machine stability characteristics under various operational conditions; and exploit this modelling data to populate pre-programmed sensor based technology to monitor stability in real time and automatically restrict lift mode operations

Personality and occupational accidents: Bar benders in Guangdong Province, Shenzhen, China

Limited research has been undertaken to explore how Chinese construction workers' personality affects their safety behavior. Inappropriate behavior on-site can instigate serious accidents, injuries, or fatality as well as incur significant costs and loss of corporate reputation. To address this dearth within the extant literature, this paper uses Eysenck Personality Questionnaire to examine the complex relationship between the personality of Chinese construction workers (especially, bar benders) and occupational accidents. A significant relationship between personality, unsafe behaviors, and the extent of injury was identified. Using the results generated, a series of practical recommendations are proffered to reinforce behavioral safety training (and reduce accidents on-site), including suggestions for conducting training programs that can be tailored to construction workers with different personality traits. © 2014 American Society of Civil Engineers

Mandatory building inspection: an independent study on aged private buildings and professional workforce in Hong Kong

Memories are still vivid on the incident: on 29 January 2010, a five-storey building at 45J Ma Tau Wai Road, To Kwa Wan, Hong Kong collapsed, causing four deaths and two injuries. The tragedy has raised public concerns about the safety of many of Hong Kong\u27s old and dilapidated buildings. Realising that the presence of ageing buildings lacking proper care and maintenance poses potential threats to residents and the public at large, since 2012, the Buildings Department has implemented the Mandatory Building Inspection Scheme (MBIS) to carry out inspection and rectification works for buildings aged 30 years or above. This book, as a pioneer to review and examine the statistics and distributions of the aged buildings in Hong Kong, provides critical insights on the building decay and neglect problems. The statistical information highlighted in the book also serves to project the estimated number of aged buildings to be covered by the MBIS in the future, and the demand of professional workforce expected for the successful implementation of MBIS. The book is useful for the practising professionals in the building industry, such as surveyors, engineers and government officials. It is also an excellent reference for students and researchers in Surveying, Construction Management and related disciplines

Building maintenance and repair: determining the workforce demand and supply for a mandatory building-inspection scheme

To deal with the existing building dilapidation problem in Hong Kong, a mandatory building inspection scheme (MBIS) has been introduced. The effectiveness of the scheme is reliant on an adequate supply of registered inspectors (RIs) to inspect and supervise repair works. To ensure that there is an adequate supply and demand of RIs to enable the implementation of the MBIS, a robust workforce planning model is proposed. The database of private buildings from the Hong Kong Home Affairs Department and a web-based survey were used to collect qualitative and quantitative data, from practitioners and professional bodies, to determine the demand and supply of labor. A quantitative modeling approach, which utilizes a labor multiplier method, revealed that there will be a shortage of RIs to meet future professional workforce demand under the MBIS. The qualitative aspect of the research reported in this paper, which addressed the perception of eligible RIs, revealed that the majority of respondents were disinterested with becoming an RI as their responsibility and liability had not been clearly defined under the current MBIS scheme. The findings provide the local government authority with the ability to visualize the workforce demand under the MBIS and articulate future workforce strategy to ensure an adequate supply of the professional workforce. As a result, the condition of buildings and the living environment of the general public will be improved with the implementation of MBIS to safeguard public safety