The NSW government has confirmed upgrades to the Barton Highway will be completed by at least 2023, three years after they were originally scheduled to be completed.
Safety upgrades to the major road linking the ACT and the Hume Highway were expected to be finished by June 2020, according to the original government plans.
Under questioning in NSW budget estimates earlier this week, NSW transport officials confirmed the project's completion had been pushed back until the 2023-24 financial year.
Transport NSW regional roads executive director Roy Wakelin-King told estimates the expansion of the project was the reason for the delay.
"The issue where there has been a change is the overtaking opportunities leading to the duplication, which has been changed as a consequence of the additional scope," Mr Wakelin-King said.
"[We need] to undertake further work in respect of both assurance and scope management, which would lead to changes to procurement and also next stages from here."
The $200 million highway upgrade consists of four stages, three of which are yet to be completed.
While the first stage, developing a federal-funded business case, was finished, the remaining stages of upgrades including safety upgrades, duplicating the road between the ACT and Murrumbateman and work on intelligent transport systems for drivers are not complete.
The state government announced $50 million for the project, which was then matched by the Commonwealth.
The federal government provided a further $100 million for the upgrades, announced in its 2018 budget.
ACT Chief Minister Andrew Barr said on Thursday he was frustrated by the delays to the project.
"In the light of the commentary from the Reserve Bank and other economists about what is needed in the Australian economy at this point, is in face to be bringing forward infrastructure projects," Mr Barr said.
"The complexities of the project have been canvassed for some time, but it is an important road that leads Canberra to the Hume Highway and the region.
"Any setback in relation to making that road safer for people to travel on is a disappointing outcome."
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When asked by his opposition counterpart on delays to road projects, NSW Regional Roads Minister Paul Toole did not say how many road projects in regional NSW were behind their intended schedule.
"Everyone would like their road to be done tomorrow. This is a government that is trying to ensure that we are building as much as we can into the regions," Mr Toole said.
"Sometimes circumstances change in relation to big projects. We have a number of big projects across the state."
Mr Toole said the delay was due to the amount of other road projects being carried out across the state.
"I think when you look at the capacity of the number of projects that we also have is, it is capacity issues," he said.
"There are issues around supply as well. We need to consider all these factors with the market as well."
The minister said the government had put out a review of environmental factors for the Barton Highway project at the end of February with public consultation under way.
Labor spokesman for regional roads Mick Veitch said more information was needed about the delays to the project.
"How good is it? Not very good if you are waiting for the government to build one of these late and delayed road projects in your community," Mr Veitch said.
"The Opposition is calling for the minister to come clean and tell the community how many more regional roads projects are late."
The Barton Highway has been regularly named one of the state's worst roads.
