The orange box on the bus that can be difference between life and death

Defibrillators have been rolled out to every NSW TrainLink coach after a trial of the life-saving equipment.

Automated external defibrillators (AEDs) can now be found on every scheduled service across the state's 143 routes, minister for regional transport and roads Jenny Aitchison announced on Saturday.

The rollout is the outcome from a trial carried out earlier last year, completed in partnership with St John Ambulance.

Access to an AED in an emergency can mean the difference between life and death.

"About 30,000 people in Australia have a sudden cardiac arrest each year and only one in 10 survive," Ms Aitchison said.

"We know using a defibrillator can improve a person's chance of survival by up to 70 per cent and having these devices on NSW TrainLink coaches means passengers experiencing a cardiac arrest on board can now be treated quickly."

The tyranny of distance and at times poor mobile phone reception can wreak havoc in cases of emergency, particularly in remote parts of the state or areas with coverage blackspots.

With AEDs able to be used safely by anyone without the need for training, they play a key role in saving lives, St John Ambulance NSW CEO Dominic Teakle said.

"St John Ambulance NSW is delighted to see this program expand, particularly into those regional and remote routes where medical help can often be further away," he said.

"We know more lives can be saved by improving public access to AEDs in our communities and making sure people feel empowered to use one in an emergency."