As reported by the Newcastle Herald yesterday, the council hopes to begin the trial in "coming months" after its launch was postponed due to the coronavirus.

If it does begin, the 11-seat bus will likely have a reduced capacity to adhere to social distancing.

The union says only three people, including a chaperone who can take control of the vehicle, would be able to be on board.

Daniel Jaggers, the RTBU's bus division president, says the council should use the delay to conduct "community consultation that was neglected prior to the trial".

He said the autonomous vehicle a "dangerous toy".

Mr Jaggers' comments follow previous union criticism of Keolis Downer for cuts to the city's public bus network.

"In a growing city in desperate need of reliable, high-capacity public transport, the wasted public funds poured into this pet project are sorely needed to put dozens of cancelled bus services back on the road and closed stops back into operation," he said.

"This is the perfect time for the City of Newcastle to discontinue this project before any more precious time and funding is spent.

"This can only be achieved by opening community consultation and hearing directly from the Newcastle locals who have been forced to tolerate inadequate, unreliable public transport for far too long."

City of Newcastle awarded Keolis Downer a $519,000 contract to launch and run what had been slated as year-long trial last April.

The council received a $5 million federal grant in 2017 to fund the trial, and a series of other technology-based initiatives.

One of those was a $600,000 on-demand transport trial launched in November.

The Herald reported in February that it had attracted only 200 passengers in the first three months.