Question to the Department for Transport:

To ask His Majesty's Government what steps National Highways has taken to ensure that infilled bridges do not have voids beneath their spans.

National Highways use assurance and inspection processes to confirm that voids are not present beneath bridge spans. The process is NH check 12 months after completion of the infilling. NH checks that a void has not formed between the infilling and the underside of the bridge by drilling small holes through the deck and inspecting with an endoscope. If there is a void, it is pressure grouted to fill it. The infilled bridge is then visually examined every 12 months, the frequency for all Historical Railways Estate structures examinations.