"We are on track for overall completion in early 2019 and have always been upfront in stating that we would need to adjust the schedules of individual zones,"it said.

The transport authority said it had been working to send a"strong message that Sydney is open for business along the light rail route during the construction",which extends from Circular Quay to Randwick and Kensington in the city's south east.

But Bek Benitez,the manager of the Oakley store on George Street,said the disruption had resulted in a major decline in customers.

"It is something that should have taken a minimal amount of time. The project wasn't thought through properly,"she said."It is absolutely frustrating."

The ALTRAC consortium that won the $2.1 billion contract to build and operate the 12-kilometre line faces"significant financial penalties"if it spends longer than the allocated time in any construction zone.

But Transport for NSW declined to say whether the consortium had paid penalties,citing commercial in confidence.

InSurry Hills and along Anzac Parade in Kensington,small businesses are also counting the cost. The owners of The Book Kitchen closed their well-known cafe and restaurant permanently last month after almost eight years,blaming construction on Devonshire Street for a plunge in customers.

Amelia Birch,who ran the Book Kitchen with her husband David,said the disruption from construction had taken a huge emotional and financial toll,and she estimated they had lost more than $100,000.

"It has uprooted our whole life. Our revenue was so low and we were unable to pay the rent. We liquidated our business and had to move out of our house because we couldn't afford to rent,"she said."We are living with family now."

Labor's transport spokeswoman,Jodi McKay,said the government should consider financial assistance to help struggling businesses.

"It's clear some are doing it tougher than the government expected and so it needs to do the right thing and look at individual circumstances,"she said.

In November,the state's Auditor-General released adamning report into the light rail line,in which it was revealed the government misled the public about the reasons for a $549 million blowout in the cost of the project in 2014.

Con Vithoulkas,who co-owns Vivo Cafe on George Street with City of Sydney councillor Angela,his sister,said his revenue had dropped by 30 per cent since construction began.

"It is a disaster. As a small business owner,I am mortgaging my house to pay my bills and my lease here,"he said."We don't know when it's going to end."

Mr Vithoulkas said his business paid almost $400,000 a year in rent for a premium spot in the CBD,yet noise and dust from construction of the line was deterring customers.

The cafe used to attract an after-work crowd until 8pm on Fridays. But that dried up quickly after construction started and the cafe now closes at 4pm.

"It's not a little problem,it's a major problem,"he said."I have to go to the landlord and beg. There is no compo – nothing,zero."

However,Transport for NSW said the major civil construction was progressively being completed with systems work for the line,including installing the third rail,signals and station equipment.

"By combining the two stages of work we're able to complete as much of the project as possible in the one sequence,"it said.