a40 closure: Transport for London will close the A40 between the Westway roundabout and the Marylebone flyover from 6: 00 PM ET on Friday 20 March until late April to carry out essential safety work. The move affects both directions on one of the busiest west London routes, which carries up to 96, 000 vehicles a day. TfL has said the full carriageway will be shut at all times and drivers should expect major disruption and plan extra time for journeys.
A40 Closure: What the works involve
The a40 closure is centred on a 2. 5-mile elevated section between the Westway roundabout and Marylebone flyover where crews will replace two expansion joints on the flyover. The carriageway rests on about 20 reinforced concrete bridge structures constructed between 1969 and 1970, and this phase targets the joints that allow the flyover to expand and contract with temperature changes and traffic movements. Because the work is highly complex, a full carriageway closure will be in place at all times for the duration of the programme.
To limit peak disruption the a40 closure has been scheduled over the Easter period when traffic flows are slightly lower and timetable planning has aimed to avoid clashes with other major roadworks where possible. TfL has warned that diversion routes and surrounding local roads will be extremely busy; signposted diversions are planned but journeys are likely to be delayed. Drivers travelling between the M25 and central London are advised to use the M4 and A4 instead, while those coming from outer London are encouraged to use the A312 Parkway or the A406 North Circular to link with the M4 and A4.
Immediate reactions
Stuart Harvey, Chief Capital Officer at Transport for London, said: “It’s vital that we ensure the A40 flyover is well maintained for the tens of thousands of people who use it each day. This essential work will allow the flyover to continue to be used safely. ” TfL has urged drivers to plan ahead and to give extra time for their journeys and has warned that bus routes will also be affected and local residents should consider Tube, rail, bus, walking or cycling where possible.
The closure follows long-running renewal work on the corridor, and transport analytics company Inrix identified a nearby stretch of the A40 as one of the capital’s most congested corridors in 2024, highlighting the scale of likely disruption when the a40 closure begins. TfL has said a comprehensive traffic signal strategy will be put in place to keep traffic moving as smoothly as possible during the closure.
What happens next
The a40 closure begins at 6: 00 PM ET on Friday 20 March and will run until late April; the exact completion date for this phase has not been confirmed. Following this phase, the A40 will be closed to westbound traffic at the Westway roundabout every weekend (apart from bank holiday weekends) until 6 July. TfL has indicated that teams will work to complete the joint replacement as quickly and safely as possible, while monitoring diversion routes and adjusting traffic signals to manage flow.
Road users should expect sustained impacts on journeys into and across west London and are advised to plan alternative routes now. Further updates on timings and any changes will be issued by the authority as work progresses and as traffic management measures are refined in response to conditions on the ground during the a40 closure.
