A40 Westway

Why we're doing the work

The Westway is a key strategic route and one of the busiest on TfL's road network. It's normally used by around 96,000 vehicles a day.

The roughly 21 bridge structures which support the carriageway and slip roads along that section of the A40 were built between 1969 and 1970 using reinforced concrete.

Major maintenance work will keep the A40 Westway and surrounding road network running safely and reliably in the future.

What we're doing

Our contractor Costain was appointed in 2020 to develop the designs and construction plans for the Westway project.

Given the scale of the structure, and that some sections are a higher priority than others, we've been doing the work in phases:

  • Phase 1 - replace the operationally critical roller shutter expansion joint (completed in summer 2022)
  • Phase 2 - replace 10 tooth/comb joints, protect parapets at high risk locations and make targeted resurfacing and concrete repairs. Construction work is planned for summer 2024

Phase 2:

Now that Phase 1 is complete, focus shifts to Phase 2.

The 10 metal (tooth-comb) joints we plan to replace are mainly large expansion joints spanning the air gaps between the concrete bridge structures supporting the A40 Westway between Wood Lane Flyover to the west and Marylebone Flyover to the East. These joints allow the bridges to safely expand and move under all weather conditions and traffic loading.

The concept design for these joints were completed. The detailed design has begun. Construction is expected to start on site in summer 2024. This will happen if we get the funding and access needed to finish the work.

During the works we will:

  • Replace 10 tooth/comb expansion joints along the A40 Westway and at Marylebone flyover
  • Resurface and waterproof the carriageway where expansion joints are replaced
  • Replace the metal work on inspection access hatches in the carriageway
  • Target repairs to the Westway drainage
  • Target concrete repairs in areas under the Westway

Lane restrictions and some partial closures of the A40 at night and on some weekends will be needed to help us do the work safely and efficiently.

Check back here for details of proposed closures/restrictions and diversion routes.

Speed limit restriction

The speed limit was reduced in July 2020 from 40mph to 30mph along the entire stretch of the Westway between the A40 Northern roundabout to the west and Marylebone flyover to the east.

Slowing the speed helps protect and extend the life of the ageing expansion joints in the road until they can be replaced. This makes it less likely we'll have to close parts of the Westway for unplanned works.

Next steps

We'll begin works in late summer 2024 on the slip roads off the Westway roundabout. This is near Wood Lane, before moving eastwards working next to Harrow Road.

There'll be road closures and lane restrictions on the A40 during the day and at night, on weekdays and weekends throughout the works. Signposted traffic diversions will be in place during the A40 Westway closures.

For more information and travel advice, check our A40 Westway works page.

What we've done

a40 westway aerial


We completed installing the new roller shutter expansion joint across the full width of the eastbound carriageway of the A40 Westway in March 2022 and the westbound carriageway in June 2022 and reopened all three lanes to traffic.

We completed associated works underneath the joint between July 2022 and January 2023. We also investigated the existing drainage of the A40 Westway.

We assessed the integrity of the safety barriers along the Westway to protect parapets at high risk places (for example, over live railways). The assessments confirmed the current arrangement is satisfactory and no other work is needed on those elements.


We completed concept and detailed design for Phase 1, including liaison with stakeholders to establish acceptable methods for traffic management and construction to carry out the work in most efficient and safe way.


We appointed Costain to move ahead with the next stage of this project after a competitive tender and selection process between March and June 2020.

Costain started design and planning work in July 2020 for a scheme to replace the major expansion joints, including one roller shutter and 10 tooth/comb joints along the Westway and Marylebone flyover, and to develop the proposals for the other high priority concrete repair, surfacing and safety barriers work where needed along the Westway.


After our March 2018 report on the investigations and options for maintaining and refurbishing the Westway and Marylebone flyover structures, a decision was made to go ahead with the project. Financial constraints at the time meant this was put on hold, but in December 2019 we decided to move forward with design and construction plans for the project.


Between 2015 and 2017 we inspected and surveyed all residential and business premises beneath the Westway to help us understand its condition.

We also surveyed different parts of the Westway elevated structures and Marylebone flyover, including the drainage, waterproofing, expansion joints, surfacing, structural concrete and parapets.

We investigated the road surface on the Westway and Marylebone flyover by digging trial holes, taking core samples and surveying the drainage system.

Aerial shot of A40 Westway

Contact us

Phone: 0343 222 1234 (24 hours)

(call charges may apply)

Call us if you have questions or comments about the scheme