A standing-only escalator trial has begun at Holborn Tube station, though many Londoners have ignored the rules and chosen to walk anyway.
Commuters have been asked not to walk up two escalators after a previous experiment found congestion was was reduced by around 30 per cent.
Passengers were reminded of the new rules by staff, electronic "stand on the right" signs and footprints on the steps.
However, some commuters defied the new rules and walked up the escalators anyway.
A third escalator will remain open for passengers to walk. Different approaches will be trialled over the next six months.
There has been a strong reaction to the change on social media:
Transport for London research found people tend to stand when escalators have a height of over 18.5m.
Their trial found 16,220 people could travel on Holborn's 23.4m escalator during rush hour if they were standing-only, compared to 12,745 on the split walking and standing escalators.
Peter McNaught, London Underground operations director, said: "We hope that this can lead to improving congestion at Holborn, making journeys easier for all of our customers".
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