This paper is going to use scaffolding works as a case study to investigate how the partnership system between main contractor and sub-contractors can enhance the site safety performance of workers either erecting or using scaffolding in construction sites.


What is Metal-Bamboo Matrix System Scaffold?

Metal Bamboo Matrix System Scaffold ( MBMSS ) is structural system which combines both the characteristics of metal scaffold and bamboo scaffold. It comprises of steel pipes ( 60% ) and bamboo members ( 40% ). MBMSS is tubular skeletal frameworks using steel pipes in the forms of main vertical members ( posts ) and horizontal members ( ledgers ) for supporting loading, and also inclined structured members ( bracings ) for lateral stability. ( Fig. 1 )

Fig. 1   The structure of metal bamboo matrix system scaffold

On the other hand, the bamboo poles are installed between the steel pipes in the form of skeletal and act as fencing in the MBMSS. Using bamboo members in MBMSS not only can reduce the loading of scaffolding, but also can increase its flexibility and adaptability to suit any contour of construction structure with different requirements resulting in enhanced productivity and efficiency than that offered by metal scaffold.
Furthermore, by incorporating other components, such as catwalks, toeboards and staircases which are specially designed, MBMSS provides stable and safe working environment and access for workers performing duties on it, whilst fully complying with various construction regulations.

Through the partnership, sub-contractors will be involved in the design or planning stage of the project with the main contractor. In this stage, both the main contractor and the sub-contractors can share their experience, knowledge and techniques to ensure the smooth progress of the project. The problems and difficulties which may arise during the progress of the project can be foreseen and be solved or avoided in this stage. Also, common goal can be set on safety measures procedures.

Through communications and constant reviewing, problems can be solved and continuous improvement can be achieved.

The following are some examples that illustrated how the partnership can enhance the safety in scaffolding works.

Making opening on the scaffolding is a common practice in construction site. These openings are used to transport the bulky materials or machinery into the building. In the past, the openings were often made by other trades of workers for the sake of convenience. This improper behaviour will ultimately damage the structure of the scaffolding and affected its stability.

Therefore, if the exact locations of opening are confirmed and make known to the sub-contractor in the initial stage, the scaffolders can erect the scaffolding to cope with these openings with additional bracings or support to sustain the stability of the scaffolding. ( Fig. 3 ) This can avoid the damage of the scaffolding by the workers and can reduce the chance of collapse of the scaffolding.

Fig. 3   The opening on the scaffolding

Metal-bamboo matrix system scaffold is not only tied to the external walls of building by 6 mm diameter mild steel bar, but also by the metal putlogs fixed with anchor bolts. ( Fig. 4 ) These putlogs are used to prevent the scaffold from declining onto the building and at the same time expelling itself away from the building. However, due the to external walls finishes, such as plastering, painting or cladding, the other trades workers ( e.g. plasterers) often remove the putlogs if it causes any inconvenience to them.( Fig. 5 )

Therefore, if the position of the putlogs can be discussed and considered with the main contractor in the preliminary stage, the suitable positions of putlogs can be determined thus reducing the chance of their removal.

Working platform

In the past, working platform was provided by the scaffolding users. To reduce the cost and for the sake of convenience, insufficient or low-quality timber boards were used as working platform on the scaffolding. Therefore, the accidents of people falling from height due to the loss of balance on scaffolding without working platform or sudden breakage of timber boards were increased.

If this problem has been considered in the design stage, installation of working platform can be included in the scaffolding scope of work. For the accessories of metal-bamboo matrix system scaffold, metal catwalks ( Fig. 6 ) and toeboards ( Fig.6 ), instead of traditional planks with adequate strength and free from patent defects, were designed and used as working platforms. These designs can avoid sudden breakage of wooden boards due to the over-loading or deterioration by weather. Besides, the accidents due to the workers stepping on the end part of the planks can also be prevented.

Fig. 6   Catwalk and toeboard are installed on the scaffold

Scaffolding related accidents often occur when workers are climbing on the scaffolding. To prevent workers climbing on the scaffolding, suitable and safe access should be provided for the workers to go from one level of working platform to another. Under the partnering with main contactor, suitable types, numbers and locations of the staircases can be determined and provided by the scaffolding company. Simultaneously, the main contractor can govern the workers to use these proper accesses. This can largely reduce the number of scaffolding related accidents, such as fall of person from the scaffold due to slipping and loss of balance.

Usually, if the space is available, a staircase tower will be provided and installed next to the metal-bamboo matrix system scaffold. ( Fig. 7 ) On the other hand, if the space is limited that additional staircase tower cannot be installed; cat-ladder (Fig. 8) can be substituted to solve the problem.

Conclusion

Through better planning, not only efficiency and quality of work can be improved, amount of rubbish and accidents can also be decreased. As a result, cost can be reduced.
Partnership between the main contractor and sub-contractors can enhance the safety performance in construction site by collective effort and better communication to identify the possible hazards, problems or difficulties in the planning stage. At the same time, proper safety measures and procedures can be designed and determined to solve the foreseeable problems, which can largely reduce the chance of accidents occurred. Together with the continuous improvement of technology of various trades and safety facilities, a safe and comfort working environment can be provided to the worker, and finally the number of accidents can be reduced to a minimum.

Copyright 2000 Francis SO Yu Shing, Wui Loong Scaffolding Works Company Limited, Hong Kong

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