Crossrail, the company building London's Elizabeth Underground line, teamed up with the Royal Society for the Protection of Birds (RSPB) to create a new bird sanctuary. To build the Elizabeth line, which spans 73 miles and cost nearly £19 billion, Crossrail dug up over seven million tonnes of soil. Half of it was shipped to the Essex coast via boats, where the materials were used to build sea defences, and restore lagoons and mudflats once lost to agriculture and coastal erosion.