The 42-kilometre-long passenger line between Adelaide's CBD and Gawler in the north is finally back in action, after multiple project delays and cost blowouts.
The state government has offered passengers free travel all day Sunday in an effort to entice commuters back to the train after an 18-month hiatus.
Taxpayers will foot an almost $900 million bill for the project, which was originally costed at $615 million.
Transport Minister Tom Koutsantonis described the project's management under the previous Liberal government as a "hot mess".
"A year and a half of frustration is now over," he said.
Only four out of 12 rail cars have been electrified, with diesel trains to continue to be used on the line until 2023, when the remaining eight electric locomotives are delivered.
The electrification of the Gawler line was first announced in 2008 under the previous Labor government, but was shelved for almost a decade until 2018, when the newly-elected Liberal government secured funding from the federal coalition.
Since then, the project has been dogged by delayed opening dates after first being slated for 2020, then 2021 and finally June 2022.
The new Labor government has promised a series of "activities and giveaways" at various stations along the train line this week, to thank the community and businesses for their patience.
"This is a great opportunity for previous users of the Gawler line — and those new to train travel — to come and try the new electrified line," Mr Koutsantonis said.
$70m 'exit fee' to rip up contract
The new Labor government has pledged to "rip up" a $2.14 billion contract with Keolis Downer, a private consortium the former Liberal government engaged to run Adelaide's rail network in 2020.
In last week's state budget, $1 million was allocated for a "commission of inquiry" to determine the most cost-effective way to end the government's 12-year contract with the company.
Liberal Party spokesman Vincent Tarzia said the opposition had acquired "new information" from the transport department revealing taxpayers could be slugged with a $70 million "exit fee" if the Keolis Downer deal is terminated before June 2023.
"Labor has the power right now to review the contract. They could find out in a matter of seconds if it will cost millions to break the Keolis Downer deal.
"That's why it makes no sense for Peter Malinauskas to pour $1 million down the drain for a Commission of Inquiry to find out information he already has access to."
Mr Koutsantonis said he didn't believe ending the contract would cost "anywhere near" the sum suggested by the opposition.
"When this [train] system was being operated by the public, it's was being operated cheaper than it is under private hands. How does that benefit the taxpayer?