Tunnelling & Underground Work SWMS

Tunnelling covers the excavation, support and construction of tunnels and underground passages — by drill and blast, tunnel boring machine, sequential sprayed-concrete methods, or microtunnelling — for transport, water, utilities and mining. Tunnelling brings together a distinctive and high-consequence set of hazards: the instability of the ground and the potential for collapse, the confined and often contaminated underground atmosphere, restricted entry and emergency egress, respirable crystalline silica from excavating rock, diesel particulate matter from underground plant, water inflow and inrush, and the heavy plant and processes used underground. An incident in a tunnel can trap and kill workers with limited means of escape, which is why tunnelling is governed by the high risk construction work framework and a rigorous regime of ground control, ventilation and emergency preparedness. This document is the overarching tunnelling SWMS that sets out the framework and the high risk construction work categories that apply across tunnelling, and it works alongside the method-specific statements for drill and blast, TBM, sprayed-concrete, shaft sinking, microtunnelling and ground support.

Tunnelling engages several high risk construction work categories under the model Work Health and Safety Regulations — work involving a tunnel, work in or near a confined space, work in or near a shaft with an excavated depth greater than 1.5 metres, work in a contaminated or flammable atmosphere, movement of powered mobile plant, and where blasting is used the use of explosives — so a safe work method statement is required before the work commences, kept readily accessible, and given to the principal contractor if one is appointed. Excavating silica-bearing rock is high-risk processing of a crystalline silica substance, and diesel particulate from underground plant is controlled against its standard. This document coordinates the ground-control, ventilation, atmosphere, silica, water and emergency controls that run across tunnelling work.

Hazards identified

9 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Engineering: a ground-support and ground-control system designed by a competent person for the ground conditions, installed in a controlled sequence so workers are not under unsupported ground, with monitoring of ground behaviour.
2. 2Engineering: forced underground ventilation designed to dilute and remove respirable crystalline silica, diesel particulate, dust and other contaminants and maintain a safe atmosphere, with continuous atmospheric monitoring.
3. 3Engineering: control respirable crystalline silica at the source — wet drilling and cutting, water suppression and dust capture — supported by ventilation, to keep airborne silica below the exposure standard, monitored against the respirable crystalline silica workplace exposure standard of 0.05 mg/m3 (eight-hour TWA), reframed as a workplace exposure limit from 1 December 2026.
4. 4Engineering: low-emission or filtered underground plant and ventilation to control diesel particulate matter, monitored against the diesel particulate matter exposure standard, currently 0.1 mg/m3 (eight-hour TWA, sub-micron elemental carbon), with a Workplace Exposure Limit of 0.01 mg/m3 (respirable elemental carbon) from 1 December 2026.
5. 5Engineering: plant-and-pedestrian separation in the headings — exclusion zones, positive communication and proximity detection where fitted — and controlled traffic in the restricted space.
6. 6Administrative: an inrush and water risk assessment with advance probing or drainage where required, and management of groundwater so it does not destabilise the works or create an inundation hazard.
7. 7Administrative: a documented underground emergency response, fire and rescue capability — refuge, self-rescuers where required, communication, escape provisions and rescue arrangements — and re-entry and withdrawal protocols on adverse conditions.
8. 8Administrative: prepare a SWMS before the work for the applicable tunnelling high risk construction work categories, and apply the method-specific statements for drill and blast, TBM, sprayed-concrete, shaft sinking, microtunnelling and ground support.
9. 9Administrative: prepare a SWMS before the work for the tunnel and confined space high risk construction work, apply the confined space entry and atmospheric controls and permits, and where the work is high-risk processing of a crystalline silica substance, a silica risk control plan with air and health monitoring.
10. 10Administrative: air monitoring for respirable crystalline silica against the respirable crystalline silica workplace exposure standard of 0.05 mg/m3 (eight-hour TWA), reframed as a workplace exposure limit from 1 December 2026, and for diesel particulate, dust and gases, with health monitoring for workers carrying out high-risk silica work and records retained.
11. 11Administrative: a documented underground emergency response and rescue capability — refuge, self-rescuers where required, communication and rescue arrangements — briefed to all workers.
12. 12Administrative: all workers must hold a valid White Card (General Construction Induction Training, CPCCWHS1001) before entering any construction workplace, with underground, confined space and tunnelling competencies verified as applicable.
13. 13Administrative: conduct a pre-shift toolbox talk covering the day's work, ground and atmospheric conditions, the controls, plant movements, required PPE and emergency and rescue procedures, and record attendance in the consultation section.
14. 14Administrative: consult workers and health and safety representatives on the work and its risks, record the consultation, and keep this document available at the workplace.
15. 15PPE: underground high-visibility clothing, head protection, eye protection to AS/NZS 1337.1, hearing protection matched to the measured noise, gloves, and Class I or Class II safety footwear with protective toecap to AS/NZS 2210.3.
16. 16Administrative: review and update this SWMS whenever the work, the ground or atmospheric conditions, the plant or the controls change, after any incident or near miss, when a worker or health and safety representative raises a concern, or at minimum every 12 months.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A tunnelling project is delivering a tunnel that spans more than one method — sinking access shafts, driving the main tunnel by TBM, and using sprayed-concrete sequential excavation through a variable-ground section. Rather than treat these in isolation, the project uses this overarching tunnelling SWMS to set the framework and the applicable high risk construction work categories, then applies the method-specific statements for shaft sinking, TBM operations and sprayed-concrete tunnelling, with ground support throughout. Ground control is managed to a support design by competent engineers across all methods, forced ventilation dilutes and removes silica, diesel particulate and gases with continuous atmospheric monitoring, and respirable crystalline silica is controlled at source with a silica risk control plan and air monitoring. Diesel plant is low-emission, plant-and-pedestrian separation applies in the confined space, and water inflow and inrush are assessed and controlled. A documented underground emergency response, fire and rescue capability — refuge, self-rescuers, communication, escape provisions and rescue arrangements — is in place with re-entry and withdrawal protocols. Each method's crew is competent and works to its method statement under the overarching framework. The SWMS, method statements, monitoring and emergency records are retained across the project.

Related legislation

• Model Work Health and Safety Act — primary duty of care; the duty to consult workers; the reckless-conduct offence; and notifiable-incident provisions, as enacted in each jurisdiction.
• Model Work Health and Safety Regulations — Section 291 high risk construction work and the SWMS preparation and review duties, the confined space provisions, and where relevant the crystalline silica high-risk processing, silica risk control plan, air monitoring and health monitoring provisions, as enacted in each jurisdiction.
• Model Codes of Practice — Tunnelling work; Excavation work; Confined spaces; and Managing risks of respirable crystalline silica in the workplace (2025).
• Where blasting is used, the explosives legislation governs the licensing and authorisation of shotfirers and the storage, transport and security of explosives; and the diesel particulate matter exposure standard, currently 0.1 mg/m3 (sub-micron elemental carbon) with a Workplace Exposure Limit of 0.01 mg/m3 (respirable elemental carbon) from 1 December 2026, applies underground.
• Victoria operates under the Occupational Health and Safety Act 2004 and the Occupational Health and Safety Regulations 2017, with the high risk construction work, tunnelling and confined space provisions applying in place of the model instruments.

Frequently asked questions