The new expected completion date for Whanganui's Fitzherbert Ave extension to Mosston Rd is August 31.
Whanganui District Council senior roading engineer Brent Holmes said an extension had been agreed on between the council and the Ministry of Business, Innovation, and Employment (MBIE).
The extension is funded under the "shovel ready" framework of the Provincial Development Unit.
"Council has also negotiated and is undertaking additional cost recoverable work for adjacent developers by utilising the main contractor to install private service connections, while established on site," Holmes said.
"This is a proactive stance to avoid these developers excavating into our pending new road once we have finished."
Holmes said although it had added time to the contract, it would assist the new housing builds to follow, with all public and private underground infrastructure pre-prepared.
The project had also been hindered by the lack of availability of construction materials, Holmes said.
"Most underground services are now in place and work is beginning on forming the pavement, kerbs and footpaths, and the widening works to Mosston Rd to accommodate the new intersection.
"The underground sewerage tanks [manufactured locally] and pump station are currently being installed at 5m deep using sheet piling and dewatering construction methods."
Work began in November to extend Fitzherbert Ave to Mosston Rd, enabling the residential expansion of Springvale and the industrial development in Mill Rd.
The 600m direct arterial link is intended to improve freight efficiency across Whanganui city and redirect traffic away from narrow residential roads and school routes.
The project includes a right-turn bay approaching from the southern end and a left-turn slip lane from the northern end of Mosston Rd.
Holmes said there was likely to be a ministerial opening on the new road link later in the year, with further details to be confirmed closer to the completion date.