There will be no down escalator at Archway station until the end of the year while work is carried out on the outdated existing ones.
Transport for London (TfL) has started the maintenance project today and will work on them one at a time, meaning there will always be one in use. There is also a staircase.
A one-way system will be in place during peak hours to stop congestion. People will have to enter at Junction Road and leave at Highgate Hill.
London Underround's customer service chief Brian Woodhead said: "I apologise to customers whose journeys will be disrupted because of the escalator work at Archway Tube station.
"Replacing the escalators at Archway will make them more reliable and ensure they can continue to run safely and reliably for years to come.
"The station will remain open throughout the work, which our engineers will work to complete as quickly as possible."
Anyone unable to use stairs is asked to catch a bus down to Tufnell Park Tube station or up to Highgate.
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