Sydney pub and oyster bar The Morrison has offered free drinks to the "whole city" if the new light rail opens to the public before Christmas.

The new downtown and south-east line has caused much angst among pedestrians and businesses during its construction, which has now gone 18 months in excess of the originally planned opening day.

But with the trams now in timetable-simulation testing along George Street, the NSW government has indicated the service will open to the public in December.

The owner of The Morrison, Fraser Short, is not so sure.

"I’m so confident that it won’t run on time that I’ll shout the whole city a drink if the tram makes it from Randwick to the stop outside The Morrison with a cargo of paying passengers by Christmas," he said.

According to the 2016 census, Sydney has approximately 3.6 million people aged over 19 years. A happy hour beer at The Morrison costs $6.

So this is a potential $21.6 million bet Short is making.

The Morrison is on the corner of George and Grosvenor, near the second-last light rail stop before the tram terminates at Circular Quay.

"Nobody wants to see the tram launch on time more than the long-suffering business owners along its route," Short said.

"But after four years of misery, broken promises and lost income, frankly we’ll believe it when we see it."

Calling it a "tram party", the exact offer is free beers to patrons who have submitted an RSVP if the light rail carries fare-paying public to The Morrison before December 25.

The drinks are upgraded to wine if the first service stopping at The Morrison is "on time", although no criteria was specified to define this.

RSVP to the tram party can be registered here, with participants updated on how the bet is going as December approaches.

More than 60 businesses are participating in class action against the state government, seeking $40 million in compensation for losses suffered during the tram line construction.

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