People using Melbourne’s City Loop will have full mobile telephone coverage within a year.

The breakthrough came after the state rail authority struck a deal with Australia’s three major mobile carriers, promising to end years of frustration for commuters plagued by mobile “dead zones”.

The new uninterrupted service has been made possible in large part by the upgrade of train driver communications systems from analog to digital.

The Minister for Public Transport, Terry Mulder, said the installation of 3G mobile infrastructure meant passengers would no longer “have to truncate a telephone call or suffer constant disruption” while travelling through the City Loop.

The project, officially known as the Melbourne Underground Rail Link, is a joint initiative between the state rail authority, VicTrack, and the three service providers -- Telstra, Optus and Vodafone.

Once activated, around 130,000 daily commuters should benefit from the new mobile network. The City Loop accounts for more than half of all train trips heading into or out of the CBD.

“This cabling will serve as the backbone for uninterrupted mobile telephone coverage.” — Public Transport Minister Terry Mulder 

As many as 9600 travellers could be connected to the network at any one time based on the City Loop’s capacity of 12 trains carrying a maximum of 800 passengers each.

The project is being coordinated by Optus on behalf of the other mobile carriers.

A spokesperson for Vodafone, Carolyn Swindell, said that Optus, as lead carrier, was responsible for the design of the infrastructure and the time-frame for launching the expanded mobile network.

Mr Mulder confirmed that works had already begun.

“Over 12km of coaxial cable has been installed inside the City Loop’s four tunnels,” he told The Citizen. “This cabling will serve as the backbone for uninterrupted mobile telephone coverage.”

The cabling system – technically known as a “leaky feeder” – is the reason many of the world’s underground rail networks – including Hong Kong’s MTR, the London Underground and, most recently, Sydney’s City Circle Line – have seamless mobile phone coverage.

James Howe, corporate affairs spokesman for Telstra, said the technology’s “proven success” was the reason why the system was implemented in Sydney and is now being installed in Melbourne.

“The key reason for using the ‘leaky feeder’ system in Australia is that it just works,” he added.

Lachlan McKenzie, of Transport for NSW, was also positive: “There have been no complaints about poor mobile service on the City Circle Line since the expanded mobile network was launched in April 2013,” he said.

The ability to install 3G mobile telephone infrastructure arose because of ongoing works to replace the existing analog train driver communications system with a unified digital radio system.

A side benefit of the driver communications upgrade was that the mobile service providers could install and operate 3G infrastructure inside the City Loop without the risk of interfering with driver communications, according to Metro Trains spokeswoman Larisa Tait. “In short, the upgrade makes it possible for commuters to gain access to full 3G mobile services,” she said.

Mr Mulder said the Coalition Government’s most important operational transport priority had been ensuring that commuter tunnels such as the City Loop employed up-to-date technology to maximise safety.

The president of the Public Transport Users Association, Tony Morton, welcomed the infrastructure deal, but said the continued up-keep of Melbourne’s rail network should take a higher priority.

“There is no question that improving the reliability of Melbourne’s train network should take priority over the installation of mobile infrastructure,” he said.

“But if the mobile service providers are footing the bill for this project with little or no contribution from the Victorian Government, then the outcome will be of great benefit to public transport users.”

No official date has been set for the launch of the City Loop’s expanded mobile network but Telstra’s James Howe said it was expected to go live “within the next 12 months”.