The A40 Westway closure between the Westway roundabout and the Marylebone flyover is expected to end in late April 2026, according to Transport for London.
The A40 Westway, one of the busiest road corridors linking west London with central London, will close in both directions for more than a month as Transport for London begins major safety works on the Marylebone flyover.
The closure will begin at 22:00 on Friday 20 March and remain in place until late April, affecting the section between the Westway roundabout and the Marylebone flyover.
With traffic volumes reaching around 96,000 vehicles per day, the route forms a critical link between the M25, west London and central London, meaning disruption is expected to spread well beyond the immediate closure zone.
TfL has urged drivers to plan alternative routes and allow additional travel time during the works.
Evidence-Based Summary
The closure of the A40 is not driven by a single maintenance issue but by the structural lifecycle of elevated road infrastructure built in the late 1960s. While the flyover structures remain fundamentally sound, expansion joints that allow the concrete bridges to move under temperature and traffic loads must be replaced periodically.
In practical terms, the works aim to extend the safe operational life of the Westway structures while avoiding larger structural interventions later.
Why the Works Are Required
The Westway corridor is supported by around 20 reinforced concrete bridge structures constructed between 1969 and 1970.
This phase of maintenance focuses on replacing two expansion joints on the Marylebone flyover, which allow the bridge structure to safely expand and contract in response to temperature fluctuations and heavy traffic loading.
Although the work involves relatively small components, accessing and replacing bridge joints within elevated highway structures is technically complex. The works require full carriageway closures in order to remove sections of road surface, access structural components and install new movement systems safely.
TfL has confirmed that continuous closures are necessary to complete the work safely and efficiently.
Why the Timing Matters
Transport for London scheduled the works during the Easter period, when traffic volumes typically fall slightly as commuters travel less and schools close. However, the authority has warned that diversion routes and surrounding roads are expected to become extremely busy, particularly during peak travel periods.
Drivers travelling between the M25 and central London via the A40 are being advised to divert via the M4 and A4 instead. Those travelling between outer London and central London are encouraged to use the A312 Parkway or the A406 North Circular Road to connect with the M4 corridor.
Public transport options including Tube, rail and buses are also being promoted as alternatives during the closure period.
Weekend Closures to Continue Until July
The disruption will not end once the main works finish. After the full closure ends in late April, westbound traffic on the A40 will face weekend closures at the Westway roundabout until 6 July, with the exception of bank holiday weekends.
These additional closures are expected to allow follow-up works and final adjustments to the newly installed infrastructure components.
A Reminder of London’s Ageing Road Infrastructure
The Westway corridor is one of many post-war elevated highway structures now approaching 60 years of service.
Across London, Transport for London continues to manage a growing programme of bridge maintenance, strengthening and component replacement as critical infrastructure built in the 1960s and 1970s approaches the end of its original design life. While the works may cause short-term disruption, TfL says the repairs are essential to ensure the structure continues to operate safely for the tens of thousands of daily users who rely on the corridor.
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Expert Verification & Authorship: Mihai Chelmus
Founder, London Construction Magazine | Construction Testing & Investigation Specialist |
