But his comments have been disputed by NSW Roads Minister Duncan Gay, who said projects on the notorious stretch of road were under way as planned and would be finished on time.

Mr Whan, who is based at Queanbeyan, said work on a new overtaking lane east of the Shoalhaven River, announced by Monaro MP John Barilaro in May last year, had come to a standstill.

"Nothing has happened for months and, annoyingly for drivers, road work speed limits remain in place while nothing at all happens."

"Down the road a bit work the section between River Forest Road and the Mongarlowe River – which has been fully planned now for some years – has not started despite being scheduled to start at the end of 2014."

But Mr Gay slammed Mr Whan's comments as "inaccurate and misleading" and said work on an eastbound overtaking lane started in August and was due to be completed this financial year.

"The works are being delivered by Palerang Council and are on time and on budget," Mr Gay said.

"Design work for the extra overtaking lane is complete, as is rock blasting needed to accommodate the works."

He said preconstruction activities for major road works from River Forest Road to the Mongarlowe River would start mid-February.

"Over 18 months, $10 million will be spent over a four kilometre section of the highway to provide an extra overtaking lane, widen road shoulders and straighten the alignment of the highway."

Mr Whan said a consistent approach was need to ensure the road was safe not only for the increased traffic volume on the highway during summer holidays, but a growing number of daily commuters who made the return trip to Canberra.

"Most people are realistic and they know there's not going to be a dual carriageway there.

"There have been big improvements to the Kings Highway in the past decade and it will always be a road which requires people to pay it some respect and drive safely.

"But we do need more overtaking lanes because it reduces peoples' frustrations."

Former NSW opposition leader John Robertson in November pledged $60 million for ongoing upgrades and safety measures if Labor wins the state poll in March.

Mr Whan said that funding would equate to $15 million each year for four years and was "affordable and necessary".

He said the state government had "dropped the ball" in regards to funding for safety improvements to the notorious highway.

While $15 million had been set aside to fund upgrades this financial year, only $9 million was allocated for 2015-16.

Mr Gay said the state government had invested $52.5 million to upgrade and repair the Kings Highway since 2011.