Box Culvert Installation SWMS

Box culvert installation is the excavation, crane placement, jointing and backfill of precast reinforced concrete box culvert units. It is high risk construction work under the WHS Regulation because it is carried out in trenches deeper than 1.5 m, on or near pressurised gas, chemical/fuel and energised electrical services, on or adjacent to road and rail corridors, and with the movement of powered mobile plant — cranes, excavators and compaction plant (s291), so a SWMS is mandatory (s299). The dominant hazard is the crane lift of heavy units: a load drop from sling, frame or anchor failure, or a load swing striking personnel or the excavation edge, is the characteristic fatality. Around it sit trench collapse where the excavation exceeds 1.5 m, crush between a unit and an adjacent unit or the excavation wall during placement and jointing, service strikes and works within a live traffic corridor, and asymmetric backfill displacing placed units. The SWMS controls the engineered lift, the excavation support, service location, traffic management and backfill sequencing. It supports the engineered design to AS 1597 and AS 3725 and does not replace it. It is supplied in eight jurisdiction editions, each citing its own Act, Regulation and regulator.

Hazards identified

8 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Use a launched or in-situ solution, or lift-and-place in a single crane operation clear of workers, so manual guidance in the crush zone is minimised
2. 2Substitution — Substitute a lifting frame with certified anchors and taglines for slung/manual guidance of units at the excavation edge
3. 3Engineering — Engineered lift study with crane capacity margin at the working radius per AS 2550, ground bearing assessed and outrigger pads/mats sized, crane set back from the excavation edge
4. 4Engineering — Battered or shored trench faces designed for the soil class where over 1.5 m, and taglines with no hands between units during placement
5. 5Engineering — Positive services location (dial-before-you-dig, potholing) before excavation, and traffic/rail corridor controls per the traffic-management plan
6. 6Administrative — Lift study prepared and signed before crane mobilisation, a dogger/rigger directing lifts, and no personnel under a suspended load at any time
7. 7Administrative — Engineered backfill sequence placed symmetrically, and a permit-to-excavate with soil classification
8. 8Administrative — Exclusion zones for the lift and the corridor, with spotters
9. 9PPE — Type 1 hard hat and Type R day/night high-visibility for all crew in the lift and corridor zone
10. 10PPE — Gloves and steel-toe boots, with hands kept clear of pinch points during jointing

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

At 7:00 am a crew from Spanline Civil sets up to place precast box culvert units into a trenched crossing beside a live road. The lift study is signed and on site, the crane is set on assessed ground with pads deployed and set back from the excavation edge, and the trench is battered to the soil class. Services were located and potholed the day before, so the crew know exactly where the gas main crosses. A traffic-management plan holds the corridor while the crane works. Each unit is lifted on a certified frame with taglines; the dogger directs it, and no one stands under the suspended load. As a unit is landed and jointed to its neighbour, the crew guide it with taglines and keep hands clear of the pinch point between units and the wall. Backfill is placed symmetrically to the engineered sequence so the units are never pushed out of line. Compaction plant is kept separated from the crew by a spotter. The crossing is completed with every lift and hold point signed, and the corridor is reopened only once the site is clear.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS 1597 Precast reinforced concrete box culverts
• Excavation Work Code of Practice

Frequently asked questions