A Melbourne driver injured when a giant sign fell from a freeway gantry, crushing her car, plans to sue for compensation.

Nella Lettieri, 53, was lucky to survive when a four-metre by five-metre sign fell onto her car on the Tullamarine freeway, near Essendon Airport, about 5.30pm on January 8.

“She’s got severe headaches, she suffered significant trauma to the head,” her lawyer Tony Carbone said.

“The cabin was crushed and it struck her in the head.”

Ms Lettieri suffered a crushing injury to her neck, was having trouble sleeping and was constantly reliving the incident, causing mental distress, he said.

“It’s turned her life upside down,” Mr Carbone said.

The legal process will be long – Ms Lettieri has to apply to the Transport Accident Commission for her injury to be recognised, which could take eight to 12 months, Mr Carbone said.

After this, she can lodge a suit against VicRoads, Transurban and any other potentially responsible parties.

There are statutory limits on the compensation Ms Lettieri can claim, but she can also seek compensation for loss of work and injuries.

On Sunday, VicRoads said initial investigations by Transurban found a stiffener plate was not installed in the gantry.

“The preliminary findings have determined that the failure has occurred at the connection of the vertical structural sign supports to the horizontal gantry beam,” the statement read.

An audit of 17 gantries with similar sign support, installed by the same contractor as part of the CityLink Tullamarine Widening Project, found plates missing in two other gantries.

While there were no signs of stress or deterioration, they have been removed.

Stiffener plates were not required to support any of the other similar signs installed in the same project, VicRoads said.

The investigation continues.

-AAP