The average on-time performance target for the south-west line is 85 per cent — below the rail operators’ benchmark of 92 per cent. 

Greens MP Greg Barber said the lacklustre figure was unacceptably low.

“There should be accountability from the transport minister. For every train that’s late, there should be a reason that’s made public,” Mr Barber said. 

The service only reached the target once in September 2013. In March and April this year, the trains were on time 75 per cent of the time. 

Trains up to 10 minutes late are still classed as being on time by V/Line.  

“I think on time means on time,” Mr Barber said. 

Warrnambool’s arrival times are the third worst in the state, behind Gippsland and Bairnsdale lines. 

A V/Line spokeswoman blamed the delays on track and train faults, as well as congestion in the city. 

She said the regional rail link project separating country and city train lines would ease the flow of regional services to and from Melbourne. 

It was a similar line from Minister for Public Transport and Roads Terry Mulder, who told The Standard yesterday that any delay on the metro network had roll-on effects to regional lines. 

He said more than $2 million had been spent on upgrading “dilapidated” rail infrastructure between Warrnambool and North Geelong, with delays associated with the works having an impact on punctuality.

“When the regional rail link opens at the end of the year, regional trains will have dedicated lines into Southern Cross Station, meaning disruptions to metro services won’t have an impact to regional trains,” he said. 

“When that project is complete, we will see a major improvement in reliability and punctuality.” 

Mr Mulder said Public Transport Victoria (PTV) would soon start a research project that could bring extra services on the Warrnambool line. 

“But for that to happen, we need to be sure there will be patronage and there is a very specific science PTV use to determine the demand for services,” he said.

“It’s not as easy as what the Greens say. You can’t just increase services by 50 per cent. There needs to be the demand. No one wants to see empty trains running along a railway line.” 

Mr Barber said the government had implemented very little of a “modest” strategic operations plan handed to the transport minister in 2011.

The report recommended adding a fourth daily service to Warrnambool by 2015 by using older trains from the Shepparton line. 

More passengers would require better facilities at Warrnambool’s station, described in the report as “inadequate even for current patronage especially at peak times”.