The discovery of 400 disused utilities, including underground pipes and cables, will push out work on the light rail network in Sydney's CBD by up to five months.

Key points: End date for light rail has been pushed back by several months

End date for light rail has been pushed back by several months Owners of utilities need to be indentified before work can progress

Owners of utilities need to be indentified before work can progress NSW Government unveils new design for rail servicing Sydney sporting venues

The mostly redundant utilities were found during works on George Street and authorities said they needed to identify the companies that own them before work could progress.

"For every redundant utility find we have to go through a two- to four-week process to validate it, because if we snip it, something really bad could happen and we could take a telecommunication cable or something," said Transport for NSW CBD coordinator general Marg Prendergast.

The utilities are in two zones, including between Market Street and King Street, which is a key shopping area.

Work was meant to finish before Christmas, but was now unlikely to finish until April 2017.

"That has meant that we will still be working in the city at Christmas," Ms Prendergast said.

"In zone five, between Market and King [streets], which is our retail precinct, there will be only low-level non-invasive work that's not as noisy.

"We will activate and really support business in the precinct.

"We will work with them to activate and promote that Sydney is still the place to come and shop and party at Christmas time."

Work on zone six, between Market Street and Park Street, is now forecast to finish in May 2017.

No delay to timing of overall project

Despite the CBD delay, the New South Wales Government was confident the overall 12-kilometre light rail project was on time and on budget.

The project, which will link Circular Quay with Randwick and Kingsford via George Street and Central, is expected to start carrying passengers in early 2019.

"We've got 14 construction zones of the 31 now being accessed by the project team, we're going to see another two this week," Minister for Transport and Infrastructure Andrew Constance said.

"There's some exciting milestones around the corner. It's disappointing, but the overall project's still on track."

Altrac, the company developing the project, said it had anticipated complexities in the CBD and it was not exactly clear what was under George Street when they started.

"The end date for the project's not affected and we've always said that we need the flexibility to change the start date and durations of those zones to meet the challenges," said Glen Bentley, the CEO of Altrac.

Moore Park light rail station unveiled

Sorry, this video has expired Moore Park light rail stop

Meanwhile, the Government has unveiled the design and look of the light rail project along Anzac Parade in the city's east, which includes a station close to the Sydney Cricket Ground and the Sydney Football Stadium.

The light rail will go from Central Station through Surry Hills into a tunnel under Moore Park and Anzac Parade. It will emerge above ground close to the stadiums.

"This station will be a key stop along the 12-kilometre route, giving fans access to our iconic sporting events," Mr Constance said.

Work in the area is already underway, with a short diversion around the works in place on Anzac Parade.