How you maintain one of the world's oldest tunnels

Travellers are being warned to expect disruption on the busiest routes between Wales and England this month, as both the M4 Severn Bridge and Severn rail tunnel will close for repairs.

The Severn Tunnel, opened in 1886, will shut for 16 days between 3 and 19 July to replace four-and-a-half miles (7km) of track.

BBC news journalist Peter Shuttleworth joined site workers to find out what it takes to maintain one of the world's oldest and longest river tunnels.