Multimillion-dollar security bollards designed to protect Parliament House from a terrorist attack have destroyed five luxury cars used to ferry federal politicians around the national capital.

The heavy steel bollards, driven by powerful pneumatic motors, are capable of springing out of the roadway with such force they can fling large trucks into the air.

But in five separate incidents since November last year - two in the past couple of weeks - bollards have been impaling Commonwealth cars, smashing everything from transmission systems to motors, and piercing the vehicles’ undercarriages.

A Comcar enters the grounds of Parliament House by driving past drives past retractable bollards. Alex Ellinghausen

The trouble began when the $126 million works to fortify Parliament House against terrorist attack - including erecting a ring of steel fences - interfered with the automatic operation of the bollards, requiring them to be run manually.

No parliamentarians were aboard any of the vehicles caught by the rogue bollards, according to the Department of Parliamentary Services. The department’s spokeswoman also said there had been no reports of injuries.

Sources have told Fairfax Media the damage was so extensive most of the cars had been written off.

The problem, apparently, is human error.

The bollards, when installed in 2005, were to operate automatically, though the system could be overriden manually.

Illustration: Matt Golding

“As a result of work to upgrade the perimeter security of Parliament House it has been necessary for a period to switch to manual operation of the retractable bollards on the Senate and House of Representatives slip roads,” according to a statement from the department.

“Five cars have been damaged by rising bollards since November 2017 when the switch to manual operation took place.”

The system has been problematic ever since it was installed as part of an $11.5 million “security enhancement” of Parliament House in 2005-2006.

Within a year, a Senate estimates committee heard a tale of woe: the new bollards had caused problems 105 times in 10 months, trapping cars, trucks and even a tractor. Politicians in cars had been trapped; a landscaping cart was lifted clean into the air, and a slow-moving tractor was impaled. In several cases, the bollards failed to retract or rise when they were meant to, or they became stuck halfway.

The system had improved since - until the anti-terrorist system began terrorising Commonwealth car drivers late last year.

Approval for the massive security upgrade at Parliament House - which included the removal of a number of mature trees and the restriction of access to the building's iconic grassed roof - was rushed through Parliament in response to terror attacks against the Canadian Parliament.

The bollards have been an ongoing problem at Parliament House - even their maintenance has caused concern.

It was reported in 2015 that intelligence and security agencies were worried that too much technical information was being published in tender documents issued for contracts to maintain the roadway security system.