People will be able to take the Waterloo & City line today for the first time since the first lockdown in March 2020.
Transport for London announced that the commuter link, connecting Waterloo and Bank stations, will reopen from 6.15am.
It is the shortest tube line, covering 1.47 miles with an end to end average journey time of just three to four minutes.
The important commuter service had been closed for over a year.
Services will now run every five minutes Monday to Friday from 6am to 10am and 3.30pm to 7pm.
TfL said the operating hours will enable customers to stagger their journeys during rush hour and provide extra capacity for people who have to travel at peak times.
The line had been due to reopen on June 21 this year.
Mayor of London Sadiq Khan said: ‘I’m delighted that the Waterloo & City line is returning from today, ahead of schedule.
‘As London’s economy continues to reopen and more people return to the offices, having this key artery connecting Waterloo and Bank stations up and running will be vital.’
During the pandemic, Waterloo & City line Tube drivers were drafted onto the Central Line to help manage the extra services required to ensure social distancing was maintained.
TfL said the number of people using the Tube had increased by more than 20% since May 17.
Catherine McGuinness, policy chairwoman at the City of London Corporation, said: ‘Today’s reopening of the historic Waterloo & City line is an exciting and vital moment in the Square Mile’s recovery as it marks a huge step on our journey back to normality.
‘The Waterloo & City line will support the return of the City’s commuting workforce back to the Square Mile as the easing of restrictions allows.
‘The additional footfall generated will also provide reassurance to the many businesses that rely on commuter traffic for trade.’
TfL said there will be occasions when social distancing is not possible as more people return to using the network, and advised people to consider waiting for the next service when necessary.
Face coverings must still be worn across the transport network.
Recent figures show that the use of public transport in Britain is still lower than it was before the pandemic started.
On May 28, bus use was 64% outside London and 65% within the capital.
The number of journeys on the mainline rail network was just 45% of normal, although that figure is provisional.
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