Auditors were called in last month to examine a host of failures to deliver the $31 million stage one of the Gundaroo Drive duplication on time, a project meant to be completed by June last year, now not expected to be finished until the end of 2018.

Internal concerns prompting the audit extend to the government's management and oversight of key contractors, what the government called an "unresponsive contractor" and a series of contract variations and extensions on the project.

It comes as the territory government faces increasing political pressure about its procurement and contract management practices, after revelations bureaucrats spent $1.4 million on Floriade last year without following due process, and a multi-million dollar contract awarded to Riverview Group to help develop Ginninderry that does not fully meet ACT procurement rules.

The delays have frustrated Gungahlin residents, as Gundaroo Drive is a key arterial road from Canberra's northernmost suburbs to the rest of the city, with weekday traffic delays further exacerbated by light rail construction on Flemington Road.

Despite the lengthy delays to stage one of the project, a Transport Canberra and City Services spokesman maintains the $31 million budget for the project would not be exceeded.

The $42,834 audit contract was officially executed last month with Vincents chartered accountants to independently examine the way the government has managed the multi-million dollar contracts for stage one of the road duplication.

Contracts show it will examine the "root causes" of the delays and cost over-runs on the project, as well as whether it met sound governance, project management and contract management practices.

Auditors will also investigate whether appropriate governance and processes were in place to manage a series of contract variations and extensions, recommend immediate action to prevent further delays and help inform the directorate's project management practices for future roads projects.

Among the potential risks identified that forced the directorate to call in auditors were failures to deliver on time and on budget, failing to implement a robust governance framework and failing to meet government priorities and the expectations of the people of Canberra.

Transport Canberra and City Services deputy director-general Duncan Edghill said the project was well behind the original schedule and delays were largely linked to the "relocation of utilities", which was causing prolonged inconvenience to the community.

"The addition of the new traffic signals at Gundaroo Drive and Mirrabei Drive, along with the widening of Mirrabei Drive also extended the project schedule," he said.

"We’re frustrated and we know the community is too – we apologise for this."

The directorate spokesman later said the delays were mainly due to the timeliness of Jemena Asset Management's "engagement with the territory's head contractor", and the government and the head contractor had "anticipated Jemena would be more responsive than it was".

The company, runs Evoenergy's gas networks in the ACT, and was contracted to replace a section of the network along Gundaroo Drive.

But Jemena spokesman Michael Pintabona said the delays were not caused by the company, rather a delay in the gas relocation project was due to a third party subcontractor, which had damaged pipes during installation, delaying completion from June-July this year until November.

He said the damage had meant coating on some of the pipes had to be repaired, while some pipeline had to be ordered to replace the damaged stock on site.

Mr Edghill would not put a specific figure on the final expected cost, or confirm it would cost taxpayers more than the original budget, saying only it would be finished "around the combined budget".

He said he was potentially concerned by all aspects of the delivery of the project, and the audit would allow the directorate to consider specific areas of focus to improve procurement and deliver future infrastructure projects.

"This is a source of significant frustration for both the community and the ACT government," he said.

"Although the Gundaroo Drive Stage One duplication has proven very frustrating, undertaking this audit on our own initiative shows we’re serious about learning our lessons from it."

Mr Edghill said the vast majority of the directorate's annual infrastructure program was delivered with comparatively little fuss, but this project was an exception, hence a focus on assessing what could have been done better.

Clarification: This article has been edited, as Jemena is part of Evoenergy, the re-named distribution arm of ActewAGL.