Bianca Elizabeth Pyke, 28, of Ravenswood, pleaded guilty to dangerous driving, evading police, driving while disqualified and possessing a controlled drug.

The court heard that Pyke, who had just bought methylamphetamine, was driving towards the CBD in a car that police were looking for.

When they did a U-turn and turned on lights she accelerated to 80-100km/h.

Road spike use was authorised but acting Sergeant Michael Grenda and Constable Benjamin Pearce-Lieutier did not have time to deploy.

When the constable threw the spikes onto the road Pyke braked heavily and swerved to the wrong side of the road forcing Sergeant Grenda to jump out of the way to avoid being struck.

She drove through the Launceston CBD weaving in and out of traffic at excessive speed. At the intersection of Wellington and Elizabeth streets she drove through a red light and smashed into another car.

"While your car was stationery you were recognised by police and you drove away," he said. The court heard that Pyke gave birth to a daughter as a 14-year-old and had suffered drug abuse and mental health problems.

He said she had a terrible driving record which included five prior convictions for evading police.

"Your record entitles to no lenience. The fact that you were trying to escape from police increased the potential danger by adding desperation to your driving and decision making,'' he said.

"The danger you posed was directly demonstrated by the way you drove towards Sergeant Grenda and then by the collision with another car with four occupants after you drove through a red light.

"The potential for death or injury was considerable and it is only good fortune that no one was killed or badly injured."