Westgate Tunnel Project – North Portal Vent Structure

The West Gate Tunnel’s ventilation system is built around two ventilation structures — one above the southern portal in the West Gate Freeway, and one above the northern portal near the Maribyrnong River. These structures do the work that keeps the tunnel breathable: drawing exhaust air up and out before it reaches the portal, so vehicles enter and exit through openings that emit nothing at all.

Austral Contractors was engaged by CPB Contractors to cut large penetrations into the North Portal vent structure.

Penetrations of this scale in a completed reinforced concrete structure demand a method that removes exactly what is intended and nothing more. We wall sawed each opening to line, cutting through the full wall thickness from a track-mounted saw fixed to the face. Every cut was made to a marked line with clean square arrises, leaving the surrounding structure and its reinforcement untouched.

Wall sawing suits work of this kind for reasons that matter on a live major project. It cuts through heavy reinforcement without impact or vibration transmitted into the surrounding structure. It produces no overbreak, so no remedial patching follows. The cut sections come out as controlled blocks rather than rubble. And it can be performed within a completed structure without the noise, dust and disruption that percussive methods bring to a site still under construction around it.

The West Gate Tunnel Project is one of Victoria’s largest road infrastructure projects, delivering a second river crossing and a ventilation system designed to meet air quality standards among the most stringent in the world.