A $131 million upgrade to hundreds of ageing Sydney train carriages contracted to be completed on Tuesday has blown out by at least six months.

The upgrade to 446 Tangara carriages – or 55 trains ­­­– will introduce new safety measures, extend their life by 10 years, improve the operations systems and increase compliance to disability standards.

The tender, awarded to UGL Unipart in July 2015, listed the completion date as May 29. But a Transport for NSW newsletter last September revised the completion date to sometime next year.

The New Daily has found three jobs currently advertised to work on the project, despite the tender reaching its end date on Tuesday.

Safety measures to be introduced include Automatic Train Protection (ATP), which was a recommendation of the Waterfall inquiry. Seven people died in the 2003 Waterfall crash that involved a Tangara class train.

The train that smashed into a buffer at Sydney’s Richmond station earlier this year also had no ATP.

A Transport for NSW spokesman said Tangara trains met required safety and engineering standards.

Seven people were killed in the 2003 Waterfall crash. Photo: AAP

He said the department was “continuing to work with its contractor to ensure that the Tangara Technology Upgrade is rolled out across the network as quickly as possible”.

A reason for the delay or revised finish date was not given.

“The design phase has been completed and integration, testing and commissioning has now begun,” he said.

But UGL Unipart is still short a ‘test and commissioning specialist’, according to a job listing spotted by The New Daily. Two other positions to work on the project were for a ‘document controller’ and ‘quality adviser’, and were listed online just last week.

The listings did not state a contract length, but were all full-time. The New Daily phoned a job listing’s contact number but it went unanswered. A spokeswoman for the contractor declined to comment.

It comes after Transport Minister Andrew Constance suffered numerous setbacks to the light rail project, including two lawsuits over contract disputes.

NSW Greens transport spokesperson Mehreen Faruqi – who is moving to the federal senate in August – said failure to deliver the project on time would likely result in a budget blowout.

“The deceptive way in which the completion date for Tangara trains upgrade has quietly been moved forward is further proof of this government’s sneaky ways around infrastructure projects, where [the] public are purposely kept in the dark,” she said in a statement to The New Daily.

“The Tangara trains upgrade has been dragging for years. It is time we see results.”

Dr Faruqi added it was “disgraceful” the Waterfall inquiry recommendation was still open.

The government recently avoided giving a revised completion date or budget update when questioned by Dr Faruqi.

Utilities Minister Don Harwin last month responded to the question on notice, in the place of Mr Constance, noting Labor was in power at the time of the Waterfall disaster.

“When this government came to power it moved as quickly as possible to start to deliver on the Waterfall recommendations. Following the completion of a technology trial in 2014, a decision was made to revise the type of technology being proposed to be rolled out to better respond to the project requirements and to respond to technological advances in the intervening period.”

He did not respond to her queries on the Tangara upgrade.

A Transport for NSW webpage on fleet delivery programs provides status updates on all projects except for the Tangara upgrade.

Despite the May 29 contract end date, a UGL statement to ASX in August 2015 put the project completion date at July this year.

UGL Unipart declined to comment.

The New Daily contacted Mr Constance and Mitsubishi Electric, which partnered with UGL Unipart for the project.