A40 Acton Bridges, Acton, London, United Kingdom

Transport for London (TfL) is currently carrying out a complex project to replace the two A40 Western Avenue bridges over the busy railway lines at Wales Farm Road and Perryn Road in Acton, London, UK.

This engineering project involves a complex construction sequence in order to maintain normal traffic and rail operations throughout the project.

Work on-site commenced in October 2005 and project completion is scheduled for the middle of 2009. The project was necessary because the bridges were built during the late 1920s and are not designed to cope with today’s volume of A40 traffic (100,000 vehicles a day).

The new bridges are also designed to ensure the safety of the railway tracks that handle all rail networks in and out of Paddington Station, including the Heathrow Express and First Great Western (800 trains, transporting 145,000 passengers daily).

As much work as possible is carried out during the daytime, but for safety reasons some work over the railway can only be carried out when trains are not operating.

A three-and-a-half-year construction programme is required because there are only a limited number of periods each night when train services do not operate. The works depend on a set sequence of operations being completed one after the other, with little opportunity for parallel working.

FULL SCOPE

Structural assessments carried out in January 2001 identified two bridges on the A40 Western Avenue, London Borough of Ealing as substandard and in need of full replacement. These were:

• A40 Wales Farm Road Bridge (over six Network Rail Great Western lines)
• A40 Perryn Road Bridge (over two Network Rail East Anglia lines)

As a result TfL commissioned transport consultants Hyder Consulting Ltd in January 2003 to design and construct new bridges to replace the existing failing structures following a business case approval of a scheme, estimated at £45.8m.

The main bridge replacement works will cost approximately £16m and TfL is funding the whole project. The scope includes:

• Providing cycle paths on both sides of the road
• Providing a toucan crossing (for cyclists and pedestrians) to replace the existing footbridge at Perryn Road
• Improving bus stops
• Closing access between the A40 and Friary Road
• Providing a new one-way access road between St Dunstan’s Avenue and Friary Road for properties on the A40
• Landscaping the full length of the scheme

BRIDGE WORKS PROGRESSING AND CONTRACTORS

The two main contractors appointed by TfL were Hyder Consulting and Alfred McAlpine. The first new bridge beams were successfully installed at Perryn Road Bridge during January and February 2007. Four pairs of new bridge beams were installed in March 2007 at Perryn Road Bridge.

This is the latest key stage of the project and follows the completion of the foundations, piers and abutments that will support the new bridge deck. The steel beams, weighing approximately 30t and measuring up to 40m long, were lifted in pairs during off peak hours over a series of weekends.

Work is also progressing at a fast pace at Wales Farm Road Bridge, where construction of the new bridge deck is underway (beams were installed in October 2006).

To build the new bridges 970t of steel girders will be used along with 6,870m³ of concrete. Extensive advance works, including the first stages of diverting gas, electricity, water and telecoms services were successfully completed during 2005.

Modifications to the overhead electrification and service cables for the railway were completed in 2006 to allow the main bridge works to progress.

Works to move traffic from existing lanes onto new routes through the site commenced in 2007, after key sections of the new bridges and service diversions was complete. This allows the remaining new sections of bridges to be built, as well as the demolition of the remainder of the existing bridges.

The new section of A40 will carry two lanes of traffic in each direction, as well as providing new cycle paths on both sides. The existing footbridge at Perryn Road is in poor structural condition and does not provide access for people with limited mobility or for cyclists without having to dismount.

It will be replaced with a new toucan crossing for pedestrians and cyclists, with disabled access. New bridges will secure the structural safety for the next 120 years and in addition Wales Farm Road Bridge has been designed to enable future rail network expansion and improvements to meet European route requirements.

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