SUNA live traffic updates is a feature of many factory-fitted and aftermarket GPS units.
SUNA operator Intelematics collects traffic data from a variety of sources, which it collates and makes available in various ways including the broadcast SUNA Traffic Channel.
Navigation devices can use the information to warn drivers of incidents and in some cases automatically route around them.
These areas have a combined population of two million.
This expansion, which is due to be completed by the end of 2014, will bring the service to more than 17.5 million motorists in a coverage area of more than 111,500 square kilometres.
"More than 200,000 Australians live further than 100km from their regular place of work, with many of these driving from their home in a satellite city to work in their nearest major city each day," said Intelematics CEO Adam Game.
"With access to SUNA, motorists will be able to see what traffic conditions are like across their entire journey before they even leave their house, making them aware of incidents that have occurred on their route so they can pre-empt delays or unexpected traffic congestion.
"It will also help them more accurately estimate their travel time, which can often change considerably if an accident has occurred on a major connecting highway or freeway."
SUNA Traffic Channel is currently available in Adelaide, Brisbane, Canberra, Gold Coast, Melbourne, Perth and Sydney.
Intelematics also operates a similar service in New Zealand covering Auckland, Christchurch, Hamilton, Tauranga and Wellington.