‘Human error’ and security bollards have led to a $30,000 damage bill for Commonwealth cars.

Three chauffeur cars were impaled by retractable electronic bollards at Parliament House when the system was switched from automatic to manual operation in November last year.

The bollards were deployed manually and hit cars from underneath as they were passing over, causing $28,935 in damage.

The bollards were unharmed.

Reports say the ongoing $126 million program of works to fortify Parliament House against terrorist attacks interfered with the automatic operation of the bollards and required them to be run manually.

Victorian independent senator Derryn Hinch attacked the offending bollards online.

“That bloody fence,” he wrote on Twitter.

“More $$$ needed. Parliament House security fence work has interfered with electronic bollard triggers.

“Three Comcars damaged so far by misfires. One gear box wrecked.”