‘Preventable incident’: Heidelberg sinkhole blamed on North East Link tunnelling crew

A sinkhole at a sports oval in Heidelberg last week was the result of a North East Link Project tunnelling crew incorrectly conducting a pressurisation test in unstable ground and could have been avoided.

Victorian Infrastructure Delivery Authority (VIDA) Roads acting chief executive Paul Roth said the $26 billion toll road project would resume tunnelling on Friday night after an investigation identified human error as the cause of the sinkhole at AJ Burkitt Oval.

An aerial view of the sinkhole at AJ Burkitt Oval in Heidelberg.Credit: Eddie Jim

Roth said the investigation found the 7.5-metre-wide, 3.5-metre-deep sinkhole appeared last Monday after crews operating a tunnel boring machine ran a scheduled “pressure test”, which pushed pressurised air towards the tunnel face.

The machine had just gone through challenging terrain and the crew did not consider data showing they had excavated more soil than expected and destabilised the ground above.

“What should have happened is, in light of the data that was available, having traversed that challenging ground and prior to that being stabilised, the test should not have taken place,” Roth said on Friday.

“If not for the decision to carry out a scheduled pressure test, this event would not have taken place. This was a preventable incident.”

Roth said the state infrastructure department was “exceptionally disappointed” and frustrated with construction consortium Spark over the incident.

Roth said the state, Spark and independent experts had put together new controls to ensure the same mistake does not happen again, including data alerts and real-time surface monitoring.

“We’ve got the very best advice from experts about what happened, and now we have measures in place to give us and the community confidence that we can tunnel safely for the duration of the project,” he said.

In February 2025, a sinkhole emerged near the tunnel’s two boring machines in Lower Plenty.

Construction contractor Spark filled in the hole with concrete last Friday. The top 2 metres of concrete will eventually be replaced with soil so local sports clubs can resume use of the ground.

Roth said on Friday that the project hoped to complete rectification works and reopen the oval to the community by the end of March. The Banyule Cricket Club uses the oval and has had to postpone training and games.

The North East Link project has completed about three-quarters of its tunnelling, with around two kilometres remaining. That includes a section dipping under the Yarra River.

Roth said the almost two-week pause on tunnelling would not delay the project’s completion, due in 2028.

A WorkSafe spokesperson said it was “monitoring the site to ensure any risk to health and safety is adequately addressed”.

More to come

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