Ongoing construction works at the State Highway 1 Loop Rd roundabout in Whangārei will draw out another three years.
National transport agency Waka Kotahi has laid out its plans for the coming months and given an estimated end date of 2025 for the project, along with the promise that there would be "minimal disruption" to traffic.
After resolving surfacing issues on the northern side of the roundabout, contractors will launch stage two sometime later this year beginning with earthworks for the new southbound lane, Waka Kotahi announced.
Stage one of the project had taken "longer than expected", the agency conceded and is expected the be completed by June this year.
Construction started three years ago in March 2019 and was initially scheduled to finish within 24 months.
Pointing to the ongoing pandemic, Waka Kotahi said: "Lengthy lockdown periods in Auckland for example made the delivery of construction materials challenging and did impact the scheduled programme of work."
But more significantly, changing the design plans from a one-lane to a two-lane roundabout mid-way through the project had caused major delays, Ann Court, member of the Northland Regional Land Transport Committee and Far North deputy mayor said.
"Waka Kotahi started off making scrambled eggs and halfway through they had to make an omelette out of it."
Court said she was generally hesitant to defend the transport agency, however in this case they were dealing with very difficult circumstances.
In November 2019, Waka Kotahi had announced $23m funding for a second lane as well as a second bridge next to an existing one over the nearby Otaika Stream and extended the constructions until early 2022.
"It should have started with two lanes to begin with. No one can plan properly when someone keeps changing the plans constantly."
The Transport Minister's "arbitrary" decision to pull the plans for a four-lane highway from Auckland to Northland had also thrown a spanner in the works.
But considering the number of trucks with heavy loads coming from and going to Northport, it was crucial to improving the safety of the intersection, Court said.
"It's getting there and it will be brilliant when it's done."
Currently, Waka Kotahi is working to resolve an issue with surfacing laid in 2021 on the northern end of the site.
"Like when baking a cake, all the necessary ingredients were present when the surface was laid, but the mix wasn't quite right, and it has taken a bit of time to understand the best way to resolve the issue," Waka Kotahi explained of the complications.
"It's important that we get this right as this section of the state highway is such a critical part of Northland's transport network."
The agency expects that part of the construction site to be "fully operational" by mid-2022.
Director of Northland engineering company Haigh Workman, senior civil engineer John Papesch, said surfacing issues as described by Waka Kotahi were "not ideal" and "not common" but could "occur from time to time".
Papesch also commented on the timeframe for the initial earthworks of stage two.
The so-called preloading process, the strengthening of the ground where the second southbound land will be constructed, will take up to six months, according to Waka Kotahi.
Papesch said that earthworks were often "the most complicated part of the project", especially when dealing with soft soil and could take some time to complete.
Meanwhile, the new bridge will be constructed to the east of the existing bridge, which will be kept for northbound traffic only.
Because of changes to the design standards, the new bridge will be about 1.8 metres higher than the existing bridge on SH1.
"The higher bridge structure means right turns into, or out of, Oaks Rd will not be possible," Waka Kotahi said.
"Northbound and southbound lanes will be separated by a centre wire-rope barrier. We have constructed a safe turning area on Portland Rd for Oaks Rd and SH1 residents to make right turns."
As the majority of work will be completed beside the road, off the state highway, the agency expects "minimal disruption" to traffic.
Waka Kotahi would not say how much the project is costing taxpayers.