Commuters frustrated with limited phone reception on Sydney trains. This is what causes the blackspots

Picture this: you have managed to secure a seat on one of Sydney's busy trains during peak hour.

You are heading home from work, and wish to do some emails on your laptop. Or perhaps, you want to partake in a social media doom scroll on your phone.

But chances are, you will be unable to do either during a chunk of your commute.

Why is phone reception bad on trains?

Dreaded black spots in phone reception impact internet access across Sydney's train lines.

It tends to happen during peak-hour congestion. When the trains are full of commuters, all our devices are trying to use the phone towers, also known as base stations.

Associate professor Le Chung Tran from the School of Electrical, Computer and Telecommunications Engineering at the University of Wollongong believes there are three possible reasons behind why black spots occur.

The first is a lack of 4G/5G coverage and the location of many base stations. 

"Mobile base stations are usually located in residential areas to serve residents," he said, adding that commuters and trains likely weren't a focus when the infrastructure was built years ago.

Trains are also big metal boxes that are made up of multiple layers of metal sheeting and metallic window tints.

This means they can shield radio waves from getting in or out of the carriage. Plus, when the trains go fast, our phones are crossing over a variety of different base stations.

Phone reception can even be susceptible to physical obstructions around trains, including terrain like tunnels, concrete walls and vegetation.

The third possible factor is limited spectrum allocation.

"The bandwidth allocated to the 4G/5G networks in those black spot areas may be insufficient," he said.

Radiofrequency spectrum allows us to communicate via our devices, and the Australian Communications and Media Authority regulates this spectrum allocation through licences.

But with the population expanding, and a growing need for more spectrum, it leaves us in a pickle.

It isn't as simple as telecommunications companies just buying more spectrum to use — they already spend millions of dollars for the spectrum they currently have.

The worst reception black spots in Sydney

Commuters told ABC News the T1 North Shore and Western Line, the T2 Inner West and Leppington Line and the T3 Bankstown Line caused the biggest frustrations.

There were also poor experiences reported with the Central Coast and Newcastle Line between Berowra to Woy Woy.

Specific black spots noted were between Lewisham to Newtown, North Strathfield to Rhodes, St Peters to Central and Wynyard to Milsons Point.

The Telecommunications Industry Ombudsman has received a series of complaints from members of the public about poor service quality or dropouts when travelling via train.

Since July 2022, the area most complained about to the ombudsman has been between Central and Stanmore, with five specific complaints.

How can I make my phone reception better?

Black spots are difficult for commuters to avoid or fix themselves, Professor Tran said, who believes it should be up to the government to prompt action on this issue.

The federal government has the Mobile Black Spot Program, which invests in telco infrastructure to improve coverage, but Professor Tran said funding for it was "limited".

"Changing the infrastructure and increasing the number of 4G/5G base stations is not an easy solution economically," he said.

"Connecting the new base stations to existing base stations is also a costly problem."

Other solutions Professor Tran suggested was for various obstacles around the train lines to be removed or limited, or investment in satellite internet systems.

Where the blame lies

A spokesperson from Transport for NSW said mobile carriers were responsible for initiating, funding and delivering the infrastructure upgrades required to improve mobile coverage and remove black spots.

They said it made sense why commuters had noticed far fewer reception issues on the new Metro versus train lines.

"Sydney Metro funded and delivered the supporting mobile telecoms infrastructure in the city tunnels and stations. An agreement was negotiated with a lead carrier to install base station equipment and enable mobile coverage for customers of all telco providers," Transport for NSW confirmed.

"On Sydney Metro Northwest all infrastructure was funded and delivered by the telcos themselves."

An Optus spokesperson said they had installed several in-building coverage solutions to enhance coverage in "challenging areas".

5G upgrades have also been undertaken around Haymarket, aimed at minimising service disruptions in Sydney CBD and the T1 line.

A Telstra spokesperson said they had a project for Sydney's CBD and other parts of the city underway to improve rail reception.

"Coverage in trains can be even trickier. Your phone sometimes needs a moment to cut through some 'noise', especially in city centres and exposed areas like along the Harbour Bridge," they said.

Vodafone said they were "always working to identify and address any potential coverage gaps" on Sydney trains.

The telcos encouraged customers to get in touch if they experience network issues in specific locations.

What commuters can do

The Telecommunications Industry Ombudsman spoke to ABC News about the issue.

"Telecommunications services are essential services, as important to our way of life as the gas and electricity in our homes," ombudsman Cynthia Gebert said.

"Dropouts and patchy service can be annoying, but for people who rely on telecommunications for employment, health reasons, and social connection, it can be even more important.

Ultimately, solving the black spot dilemma is complicated given the many different technical factors at play.

For commuters though, complaining to their specific telco if there's a persistent problem could just set a precedent for change.