Senior officials from Transport for NSW told a budget estimates hearing late on Tuesday that they planned to replace 4039 diesel and gas-powered buses in greater Sydney with electric vehicles by 2035,followed by those in the outer metropolitan area by 2040,and regional areas by 2047.

The government has about 100 electric buses operating in greater Sydney,while another 101 are on order for delivery by June next year.

The number of new buses to be bought next financial year will be determined by a business case,which is expected to be completed by November.

Despite the timeline blowout,former transport minister Andrew Constance said he was proud to have made the commitment.

“Both sides can squabble over dates of delivery but the key is to get this happening at lightning speed because the cost is too great if we don’t take action on climate,” he said. “I deliberately and proudly set a goal of 2030 to send a signal to the market that the Berejiklian government was serious about moving on electric buses.”

Labor transport spokeswoman Jo Haylen said the government’s promise to roll out zero-emissions buses by 2030 had become farcical.

“The premier makes a massive understatement when he says this project has fallen short. It is 17 years,or almost two decades late,” she said.

Haylen said the delay had “serious implications” for both the future of our bus fleet and for NSW’s future emissions targets.

The details about the extent of the delays came just hours after Infrastructure and Cities Minister Rob Sharp told budget estimates on Tuesday that the government’s goal was now to achieve “net-zero” across the bus fleet in greater Sydney by 2035.

Under the government’s franchise model for bus services,the government owns the buses which are operated by private companies.

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