At Monday night's meeting councillors voted to approve Cr Leigh Colacino's motion calling on council to write to the government outlining its concerns about the road closure's impact on the Illawarra.

Transport for NSW plans to close the road for two one-month periods in the first half of 2020 to allow for work to stabilise the surface.

Cr Colacino's motion pointed out concerns with the closure cutting off access to medical providers, emergency services, businesses and schools.

Part of the proposed letter would call for the road to be opened to one-way traffic for a few hours a day.

Cr Colacino said the daily opening of the road had to happen "otherwise this is going to be a massive disaster".

"This isn't like the closure of Bulli Pass when that was closed last year," Cr Colacino said.

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"This is completely different."

Cr Colacino said all but one of the northern suburbs residents he had spoken to understood the need for the work to be carried out.

"If that road does fail that road could be lost for a year," he said.

"We only have three main access roads down the escarpment. If something happened on Bald Hill and Mt Ousley, this city would be shut off."

Cr Janice Kershaw added a few items to the motion, including sending the letter to Heathcote MP Lee Evans and also advertising a planned public meeting about the closure.

Cr Kershaw said Transport for NSW project manager Dave Chenery would be at a public meeting at Coacliff Community Hall on August 28 at 8pm.

The councillor said the closure would have serious ramifications for the whole city.

"This closure will have the biggest effect on our residents and businesses than any other road closure has in this city," Cr Kershaw said.

"It might just be happening north but this closure is going to impact significantly."