PART XI | EXCAVATION AND TUNNELLING WORKS |
| General requirements on excavation work |
77.—(1) It shall be the duty of the occupier of a worksite where excavation works are carried out to comply with paragraphs (2) to (11).| (2) Subject to paragraph (3), where the depth of any excavation in a worksite exceeds 1.5 metres or where the banks are undercut, adequate shoring by underpinning, sheet piling, bracing or other means of shoring shall be provided to prevent collapse of the excavation, or any structures adjoining or over areas to be excavated. |
| (3) No shoring shall be required under paragraph (2) if the excavation in the worksite has been examined and certified by a professional engineer to be safe without any shoring. |
| (4) Where the depth of any excavation in a worksite exceeds 4 metres, adequate shoring by underpinning, sheet piling, bracing or other means of shoring shall be made or erected in accordance with the design of a professional engineer to prevent collapse of the excavation, or any structures adjoining or over areas to be excavated. |
| (5) Where the depth of any excavation in a worksite exceeds 4 metres, no work (other than excavation or shoring operations) shall be carried out inside the excavation until after a certificate under regulation 78(2)(ii) has been issued in respect of the underpinning, sheet piling, bracing or other means of shoring for that excavation. |
(6) During any excavation work in a worksite, all reasonably practicable measures shall be taken —| (a) | to prevent any person being trapped by the collapse of the excavation; | | (b) | to prevent any person being struck by an object, such as an excavating machine or by any material dislodged by the machine; | | (c) | to prevent any person falling into the excavation; and | | (d) | to prevent any person inhaling, or otherwise being exposed to, carbon monoxide or another impurity of the air in the excavation. |
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| (7) Excavated material or other superimposed loads shall be so placed away from the edge of the excavation in a worksite to prevent the materials or other loads from falling into the excavation, or cause the banks to slip or cause the upheaval of the excavation bed. |
| (8) The open side of any excavation in a worksite which exceeds 2 metres in depth shall be provided with adequate guard-rails to prevent persons from falling into the excavation. |
| (9) Notices shall be put up at appropriate and conspicuous positions to warn persons about the excavation in a worksite. |
| (10) The excavation in a worksite and its vicinity shall be inspected by a designated person after every rain storm or other hazard-increasing occurrence. |
| (11) Where any inspection made under paragraph (10) reveals that the excavation in the worksite is not safe for entry, the designated person shall immediately inform the project manager of the worksite of the unsafe condition. |
| (12) Upon being informed, the project manager of the worksite may order that all works within the excavation cease immediately and revoke any permit-to-work issued for such work. |
| (13) It shall be the duty of the designated person to take, so far as is reasonably practicable, such measures as are necessary to ensure that any inspection carried out under paragraph (10) is conducted properly. |
| (14) [Deleted by S 434/2024 wef 01/06/2024] |
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| Duties of professional engineers on excavation |
78.—(1) It shall be the duty of a professional engineer who designs the underpinning, sheet piling, bracing or other means of shoring as required under regulation 77(4) for an excavation to —| (a) | take, so far as is reasonably practicable, such measures as are necessary to ensure that his design can be executed safely by any person constructing the underpinning, sheet piling, bracing or other means of shoring according to his design; | | (b) | provide to any person who is constructing or who is to construct the underpinning, sheet piling, bracing or other means of shoring all design documentation (including all relevant calculations, drawings and construction procedures) as is necessary to ensure that the underpinning, sheet piling, bracing or other means of shoring is constructed according to his design; and | | (c) | ensure that the structures adjoining or over areas to be excavated are safe to any person working on or near the structure by reason of such underpinning, sheet piling, bracing or other means of shoring. |
(2) It shall be the duty of —| (a) | the professional engineer who designs the underpinning, sheet piling, bracing or other means of shoring for an excavation; or | | (b) | any other professional engineer who is appointed by the occupier of a worksite to oversee the construction of the underpinning, sheet piling, bracing or other means of shoring in the worksite, |
| to take, so far as is reasonably practicable, such measures as are necessary to ensure that the underpinning, sheet piling, bracing or other means of shoring — |
| (i) | is constructed in accordance with the design of the professional engineer who designed it; and | | (ii) | is safe for its intended use when completely constructed and if so, issue a certificate stating that the underpinning, sheet piling, bracing or other means of shoring is safe for its intended use. |
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| Access and egress from excavation |
79. It shall be the duty of the occupier of a worksite where any excavation work is carried out to ensure that —| (a) | safe access to and egress from the excavation in the worksite is provided where persons are required to work in the excavation; and | | (b) | the access or egress referred to in paragraph (a) is sufficient in numbers and installed in such locations so as to be readily accessible. |
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| 80. It shall be the duty of the occupier of the worksite where tunnelling works are carried out to comply with regulations 81 to 87. |
| Stability of tunnelling work |
81.—(1) Where tunnelling works are being carried out in a worksite, all reasonably practicable measures such as shoring, shot-creting, supports by means of rock bolts, segments or steel sets, or other measures, shall be taken —| (a) | to ensure the stability of the tunnel; and | | (b) | to prevent any person being trapped by the collapse of the tunnel or being struck by an object falling into the tunnel. |
| (2) The roof, face and walls of the work area in the tunnel shall be examined and tested before the start of the tunnelling works and thereafter at regular intervals to ensure that it is safe for persons at work in the tunnel. |
| (3) Adequate clearance or refuge area shall be provided and maintained to prevent workers from being caught in between or struck by any part of any vehicle, fixture or equipment within the tunnel. |
(4) All tunnels or shafts in a worksite shall be properly designed and constructed —| (a) | to prevent the collapse of the shaft or surrounding earth; and | | (b) | to prevent flooding. |
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82. In a worksite where tunnelling works are carried out —| (a) | all work areas in a free air tunnel shall be provided with appropriate ventilation system to ensure adequate supply of fresh air; | | (b) | all reasonably practicable measures shall be taken to ensure that the air in the tunnel where a person has to work is free from flammable gases and vapours and contains —| (i) | at least 19.5% oxygen by volume; and | | (ii) | not more than 23.5% oxygen by volume; and |
| | (c) | air that has passed through any underground oil or fuel storage areas shall not be used for ventilation in the tunnel. |
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83. In a worksite where tunnelling works are carried out —| (a) | all areas in the tunnel shall be adequately illuminated; and | | (b) | emergency generators are provided to ensure adequate illumination of the tunnels and work areas in the event of a failure in the power supply. |
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| Access to and egress from tunnel or shafts |
84.—(1) Safe access to and egress from any tunnel in a worksite where tunnelling works are being carried out shall be provided where persons are required to work in the tunnel. | (2) Where persons have to descend in a shaft in a worksite, an alternate means of egress from the shaft shall be provided for emergency purposes. |
| (3) Where persons have to descend in a shaft in a worksite which exceeds 24 metres in depth, a lift shall be provided for the transport of men and materials. |
| (4) All combustible materials shall, as far as is reasonably practicable, be kept away from such lift and access way referred to in this regulation. |
(5) In a worksite where tunnelling works are carried out —| (a) | proper control of ingress and egress of persons to and from any tunnel under construction in the worksite shall be exercised; | | (b) | a chart listing the names of persons working in the tunnel and their location of work shall be displayed at the main entrance to the tunnel and be regularly updated; and | | (c) | notices to warn persons against unauthorised entry shall be displayed at all points of entry to the tunnel. |
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| Plant and ancillary equipment |
85.—(1) All plant and ancillary equipment necessary for the conduct of work in any excavation or within a tunnel in the worksite shall, so far as is reasonably practicable, be —| (a) | of appropriate design and construction; | | (b) | of sufficient capacity; | | (c) | safe and without risks to health; and | | (d) | adequately maintained. |
(2) Without prejudice to the generality of paragraph (1) —| (a) | all supply lines to pneumatic tools used within a tunnel in the worksite shall be fitted with water traps and where appropriate, safety chains or wires; | | (b) | hydraulic oils with flashpoints which are lower than the working temperatures in the tunnel shall not be used in the worksite; | | (c) | only high pressure hydraulic hoses and coupling shall be used in the tunnel and such hoses shall be properly protected; | | (d) | only fire resistant hydraulic hoses shall be used in hydraulically activated machinery and equipment used in the tunnel; | | (e) | all hydraulic lines shall be protected by insulation or other screening where there is a risk of burning through human contact; | | (f) | only flameproof equipment shall be used whenever there is danger of the presence of flammable or explosive gases; | | (g) | no petrol driven internal combustion engine shall be used in a tunnel; | | (h) | no diesel engine shall be used in a tunnel unless it is so constructed that no air enters the engine without first being cleaned, and no fumes or sparks shall be emitted by the engine; | | (i) | oil, grease or fuel stored in the tunnel shall be kept in tightly sealed containers in fire resistant areas at safe distances from explosives, magazines, electrical installations and away from the bottom of shafts; | | (j) | gasoline or liquefied petroleum gases or other highly flammable substances shall not be used in the tunnel without the approval of the project manager of the worksite; and | | (k) | all gasoline or liquefied petroleum gases or highly flammable substances used in the tunnel shall be removed immediately after use. |
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86.—(1) Effective and reliable means of communication, such as a telephone network, shall be provided at intervals of 100 metres along the tunnel in the worksite, including outside the portal or at the top of the shaft, and maintained at all times.| (2) Any code of audio and visual signals used shall be conspicuously displayed near the entrances to the worksite and such other locations as may be necessary to bring it to the attention of all persons concerned. |
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| 87. Appropriate control measures shall be implemented to prevent any unauthorised person from tampering with fittings, valves or other controls regulating air supply, lighting, electricity or any monitoring system used in connection with any work in the tunnels in the worksite. |
88. It shall be the duty of —| (a) | the employer of any person who carries out any work in a tunnel in a worksite; or | | (b) | the principal under whose direction any person carries out any work in a tunnel in a worksite, |
| to ensure that the person does not carry out the work unless the person has received adequate safety and health training to familiarise himself with the hazards associated with such work and the precautions to be observed. |
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89.—(1) Where 25 or more persons have to work underground in a worksite at any one time, it shall be the duty of the occupier of the worksite to ensure that at least 5 such persons are persons who have been trained in rescue procedures, resuscitation, the use, care and limitations of breathing apparatus and the use and maintenance of fire fighting equipment.| (2) Where more than 4 but not more than 24 persons have to work underground in a worksite at any time, it shall be the duty of the occupier of the worksite to ensure that at least 2 such persons are persons who possess the training specified in paragraph (1). |
| (3) It shall be the duty of the occupier of a worksite where tunnelling works are carried out to provide and maintain sufficient suitable breathing apparatus for use by persons employed to work in a tunnel in the worksite. |
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| Fire-fighting facilities and procedure |
90.—(1) It shall be the duty of the occupier of a worksite where tunnelling works are carried out —| (a) | to provide adequate and appropriate fire-fighting facilities in every tunnel in the worksite including a fire alarm system connected to the ground level; and | | (b) | to conduct at least one joint exercise for fire and rescue purposes together with the Singapore Civil Defence Force in the course of the tunnelling works. |
| (2) Before conducting the joint exercise referred to in paragraph (1)(b), it shall be the duty of the occupier of the worksite to consult the Singapore Civil Defence Force. |
(3) It shall be the duty of the occupier of a worksite where tunnelling works are carried out to ensure that —| (a) | the procedure that is to be followed in the event of an outbreak of fire is displayed at prominent positions both inside and outside every tunnel in the worksite; | | (b) | every person employed in the tunnel has received instruction on the procedure referred to in paragraph (a); and | | (c) | a fire drill is held at least once in every 3 months in the worksite. |
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