Millions of Londoners were forced to find alternative ways to travel on Thursday as the UK capital’s Underground network was in the grip of what may be its biggest strike in more than a decade.

Commuters packed on to buses or walked to work, with Tube services set to be disrupted until Friday morning. London Underground’s boss Mike Brown warned that the strike — called in a dispute over working hours — will cause “big disruption” and branded it “totally unnecessary.”

About 4 million journeys are typically made on the Underground each day, so when the system is down, the city comes close to grinding to a halt.

Without the trusty Tube, as the Underground system is widely known, commuters and tourists alike were forced to find their way to their destinations by bus, train, bicycle, taxi or on foot.

A time-lapse video posted to Instagram Wednesday evening, when the strike started, shows commuters climbing over the walls surrounding the steps of the Oxford Circus station to try to catch the last trains home.

Abbie Morrow posted a photo to Instagram showing the clogged streets of London as seen from her view on an hour and 15-minute bus ride.

For those who preferred to trust their own feet, Britain’s Independent newspaper tweeted an image of a pedestrian-friendly map showing walking times between stations.