Photo: Jonathan Mitchell
Lower Hutt's biggest transport project in decades denies it has been newly costed at over a billion dollars.
Riverlink has a publicised budget of just over $700m to shift Melling railway station, build a new bridge into the city off State Highway 2 over Te Awa Kairangi and improve stopbanks.
Since winning the job, a joint venture of builders Fletcher and engineers Aecom has been working on what is called an interim project alliance agreement.
This is typically a construction stage when new costs can emerge.
Cost over-runs are bedevilling many big infrastructure projects, amid criticism of inadequate business cases and poor coordination.
"The alliance has been reviewing the consented design, and building an understanding of the scope, to confirm a price to deliver the project," Riverlink programme director Rod James told RNZ in a statement.
"At this stage, there are no indications that construction costs are likely to exceed $1b."
The price confirmation work would be done by December.
The project will shut the Melling train line for 18 months from July next year, "a bitter pill", according to the regional council.
A cycleway job just south of Riverlink - like it, involving interference with services alongside Kiwirail's train tracks and a partnership involving Waka Kotahi and council - has blown out its budget by three times to over $60m, in part due to poor planning and not investigating properly the ground conditions and all the broadband and other cables under it.
That track from Normandale overbridge to Petone station, less than 3km long, was due to open last month - years late - but has not yet.