Network Rail will carry out upgrades at Mitre Bridge level crossing in west London, affecting Southern and London Overground services between Clapham Junction and Watford Junction from October 25 to 28.
Engineers will work around the clock to replace rails, sleepers, drainage systems and signalling equipment.
Jenny Saunders, customer service director for Southern, said: “I know these works will mean some journeys through west London will be disrupted over the October half term, but they’ll also bring long-term reliability for key infrastructure which our services rely on through west London for plenty of half terms to come.
“If you’re planning to travel between October 25 and 28, we’ve got ticket acceptance in place with buses and other train operators to help you get where you need to be, and I encourage passengers to check online before travelling.”
Network Rail says the work is necessary to keep the railway safe and remove a speed restriction that currently impacts services.
The crossing, which is at the end of its design life, provides access to a busy industrial estate in Willesden.
Additional work planned during the closure includes renewing 2,000 metres of high-voltage power cables between Clapham Junction and West Brompton, as well as upgrading track points at Kensington Olympia.
Gary Walsh, director for Network Rail’s West Coast South route, said: “I’d like to thank passengers, freight customers and local businesses in advance for their patience while we carry out this important work to keep Mitre Bridge level crossing safe and reliable for years to come.
“To complete our work safely, we need to close the railway for four days between 25 and 28 October.
“We’re asking London Overground and Southern passengers to plan their journeys in advance and check before travelling.”
The level crossing will be closed to road traffic from 1.40am on October 25 until 5.15am on October 29.
Rory O’Neill, general manager for London Overground at Transport for London (TfL), said: “This essential infrastructure work by Network Rail is crucial to maintaining the safety and reliability of London Overground services for the long term.
“I apologise for any inconvenience and recommend planning ahead, checking your journey before you travel, and allowing extra time while these improvements are underway.”
Passengers are advised to use National Rail Enquiries or the TfL website to check their journeys and plan ahead.
Travel information will be available from four weeks before the closure.
Replacement transport and ticket acceptance arrangements will be in place on alternative routes.
The improvements are intended to support the long-term reliability of both passenger and freight services through the area.
