A new car park installation is expected to mitigate the "unacceptable risk" faced by WA Parliament House in the event of a terrorist attack.

A number of concrete liners, purchased from Maddington Concrete Products, have been installed in the forecourt of Parliament House as “Hostile Vehicle Mitigation” infrastructure, in a bid to stop rogue cars.

The concrete liners. Credit:9 News Perth

The decision to install to the liners were made on a recommendation by Parliament House executive manager Rob Hunter, who said while their crude appearance wasn’t ideal, they were necessary.

“The assessment determined we had an unacceptable risk and this, combined with the national threat level of ‘probable’, contributed to the decision to recommend some type of security infrastructure,” he said.