Toni Smith, 19, is accused of assaulting the female victim and stealing the keys to her car during the alleged incident in Camperdown on Sunday.

The accused woman appeared in Portland Magistrates Court on Tuesday charged with robbery and other offences.

Camperdown police Constable Ashley Pitt alleged Ms Smith approached the victim at Camperdown's Woolworths supermarket on Sunday about 8pm and asked for a ride to the train station.

The victim, who didn't know the accused, agreed.

Once at the station, Ms Smith allegedly lunged at the victim, pushing her and holding her against the driver's-side door.

She then reached over and grabbed the car keys out of the ignition.

Constable Pitt said the victim was shaken and felt violated and frightened.

He alleged Ms Smith said to the victim "this is a carjacking".

Constable Pitt said Ms Smith told the victim to get out of the car and when she refused, the accused punched her to the left side of the face.

She then allegedly threatened to stab the victim with a knife, Constable Pitt told the court.

He said the victim was left shaking uncontrollably and traumatised.

The court heard Ms Smith left the scene with the car keys and the victim rang 000, telling an operator that she feared for her life.

The accused woman was located at the scene and subsequently arrested.

The court heard she was already on bail for failing to appear in court on charges of criminal damage and trespassing.

Constable Pitt said the accused refused to answer police questions and the car keys remained outstanding.

A lawyer for the accused told the court that Ms Smith was a young offender with no criminal history and there was no guarantee she would face a period of incarceration.

Magistrate Nunzio La Rosa said he accepted that the woman suffered mental health issues.

But he said the offending involved an attempted carjacking and robbery on a good Samaritan.

"It may not be the most serious example of the offence but it is still a disturbing scenario," Mr La Rosa said.

The magistrate said it would be a bold submission from the prosecutor that the only outcome would be an immediate jail term.

He said a community corrections order could be within range and that he believed relevant bail conditions could mitigate the risk of the woman reoffending.

Ms Smith was granted bail with strict conditions, including she not attend Camperdown or contact the witnesses for prosecution.

She must take part in the Court Integrated Services Program and will appear in court again on February 14.

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