Vintage buses will rumble up and down George Street in Sydney this weekend to mark the end of an era for the CBD's main thoroughfare.

From 4:00am on Sunday, buses will no longer run down the street as construction begins on the new light rail tracks.

To mark the occasion, some of Sydney's oldest buses will roar back to life, to take passengers on free rides up and down George Street between Railway Square and Bridge Street, from midday to 5:00pm on Saturday.

The range of buses from different eras are on loan from the Sydney Bus Museum.

Among them will be some of the original New South Wales government buses which have trundled down George Street since the 1930s.

A bus travels down George Street at Martin Place in February 1971. ( Sydney Bus Museum: John Ward )

The Transport Minister Andrew Constance said it was an opportunity to celebrate past modes of travel while looking to the future.

"This weekend Sydney changes forever and what a great way to celebrate with the bus museum of Sydney, the historic buses," Mr Constance said.

"It's an opportunity for the community to recognise Sydney's bus history on George street, but most importantly with an eye to the future.

"Light rail is going to transform this city, it's going to be futuristic and it's going to be exciting."

With the new bus timetable beginning on a long weekend, the Government has conceded that the first real test will be when commuters return to work on Tuesday morning.

"There'll be teething problems, I know everyone is going to jump up and down about that, but we've got to get this city right and so there's going to [be] pain associated with the build," Mr Constance said.

The Government's CBD Coordinator Marg Prendergast said there would be extra transport staff, bus marshalls and police available to help commuters find their way to their new stops on Tuesday morning.