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

Given the scale of the structure, and that some sections are a higher priority than others, we plan to do the work in phases:

  • Phase 1 - replace the operationally critical roller shutter expansion joint. We plan to complete this by summer 2022
  • Phase 2 - replace 10 tooth/comb joints, protect parapets at high risk locations and make targeted resurfacing and concrete repairs. This is proposed for 2023/24

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

Phase 1:

We have worked with interested parties to plan access and agree how to offset the temporary impact of the construction works.

In March 2022 we finished replacing a large metal roller shutter-type expansion joint (4 metres wide) which runs across all lanes of the eastbound carriageway of the A40 within section 4 (see the map above) near Acklam Road.

We're currently working to finish replacing the large metal roller shutter-type expansion joint (4 metres wide) which runs across all lanes in the westbound carriageway.

We expect this work to be completed in late summer 2022.

To complete key elements of the work we have had to:

  • Install temporary plates over the joints to allow the work to be carried out more efficiently and safely

  • Break out and remove the old joint materials and concrete

  • Reconstruct the concrete deck to allow the new joint installation

  • Install a new roller-shutter expansion joint with a 50-year design life within the A40 carriageway, over Acklam Road

Replacing the joint involves breaking out and removing the supporting concrete using a low-vibration method called hydro demolition, where a high-pressure water jet breaks down the concrete without damaging the structure. This method has proved to be far quieter than traditional methods of concrete removal.

Lane closures

To help us do the work safely and efficiently, lanes are closed on the Westway while we replace the expansion joint. At least two traffic lanes operate at all times on weekdays in each direction for traffic.

The Westway carriageway is closed overnight and on weekends, in one direction at a time, to give us access to the middle section of the road. Alternative traffic routes are signposted.

Phase 2:

The 10 metal (tooth-comb) joints 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 weather conditions and traffic loading.

Concept design for these joints is progressing, with the aim to be on site in summer 2023 if we get the funding and access we need, including for advance monitoring and investigations as well as proposals for managing construction and traffic.

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
  • Target concrete repairs in areas under the Westway
  • Investigate and repair the existing drainage
  • Replace the metal work on inspection access hatches in the carriageway

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

We plan to create the detailed design for this phase later in 2022. If we get the necessary funding for construction, we could be on track for other major joint replacement and maintenance works to start on site in 2023.

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.

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 reopened all three lanes to traffic.

We also completed installing the temporary plating system in the westbound carriageway across the full width of the carriageway - this will allow us to permanently replace the roller shutter joint in the westbound carriageway.


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)

(TfL call charges)

Call us if you have questions or comments about the scheme