The construction team building the Buckle St underpass in Wellington says vehicles could be using it by the end of October.
The $120 million upgrade to the capital's War Memorial Park is a government project tied to the centenary of the Gallipoli landings during the First World War.
The manager of the construction team, Duncan Kenderdine, says the opening of the National War Memorial is about 400 days away, and the construction is going to plan.
He says the project is up to the construction of the underpass tunnel, and the team is just nine concrete pours away from finishing the floor.
Mr Kenderdine says the whole project is on track to be finished in time for Anzac Day 2015.