Everybody knows the tube etiquette is that escalator passengers must stand on the right, leaving the left-hand side free for walkers. But back in 2015 Transport for London caused concern among passengers at the busy Holborn Tube station by telling passengers to stand on both sides in a bid to ease congestion.

Holborn station is one of the busiest stations on the tube network and has a lengthy 23.4 metre long escalator leading up to the ticket hall. Many commuters avoid the steep climb and choose to stand on the right, causing congestion at the bottom, whilst the left-hand side of the escalator remains largely empty. If everyone stood on both sides would that double the number of people using the escalators and get everyone to the surface quicker?

Celia Harrison, Neera Kukadia, Paul Stoneman and Grant Dyer from London Underground presented a fascinating study of the experiment at Holborn at the Lift & Escalator Symposium in 2015.