In six month time and two phases, Metrail carried out extensive refurbishment works on one of London's most important bridges. The works included waterproofing 10,000m2 with GCP ELIMINATOR® as well as concrete repairs.

  • Challenge
  • Solution approach
  • Technology

  • Execution

  • Result

The challenge

In 2020 the City of London Corporation started essential refurbishment work on London Bridge which had become vital to ensure the bridge remains operational for many years to come.

Main contractor, F M Conway, had overall responsibility for the refurbishments works which included the replacement of 24 damaged bearings on the north and south abutments. F M Conway selected Metrail to carry out the waterproofing and concrete repairs.

Solution approach

Rather than completely replace the running surface of the motorway, Metrail employed a cost-effective, long-term solution. Our technique: drilling holes into the concrete to inject a highly specialised resin product whose job was twofold. One: dispace any groundwater trapped below the surface. Two: fill in all voids in the sub-formation.
Over 20,000 holes needed to be drilled, which was carried out with either hand-held drilling tools or an automated drill rig. A standard 600 x 600 mm grid pattern was adopted from the edge of each slab, which is equivalent to one hole per 0.4m2.

Facts & Figures

When?
March - August 2020

Where?
London Bridge

How?

Waterproofing and refurbishing the bridge deck

Technology
GCP ELIMINATOR® a high performance waterproofing membrane

Result
Work completed on time and budget, with the bridge remaining operational for many years to come

Did you know?

The first river crossing on the site was thought to have been created by the Romans nearly 2,000 years ago. Later ones were destroyed by invasions, storms and fires. The stone bridge in medieval times was packed with houses, shops and chapels.

The current bridge was opened in 1973 after the old bridge was sold to America.

Solution approach

Our work scope covered structural concrete repairs, removal of existing waterproofing including deck scrape, fine milling, blasting and re-waterproofing. The total area of waterproofing was approximately 10,000m2.
Renewing the waterproofing involved removing the existing surface of the carriageway and footway, carrying out any necessary concrete repairs and then applying and testing the waterproofing system before resurfacing the bridge.

Technology

For this project, we installed the internationally proven waterproofing system supplied by GCP (formerly Stirling Lloyd) known as Eliminator. The Eliminator is a high-performance waterproofing membrane based on Methyl Methalcrylate resins which cures rapidly to provide a tough and flexible seamless membrane. Metrail is a GCP approved contractor licensed to apply and install the complete range of Sterling Lloyd waterproofing and expansion joint products. Stirling Lloyd provide technical back-up and support whenever it is needed.

The success of any waterproofing system is dependent on the surface preparation.

Following scraping of the old deck and fine milling, extensive concrete repairs were required on the exposed bridge deck to ensure the surface was clean, dry and structurally sound to allow application of a primer. On completion of the concrete repair work the GCP Eliminator waterproofing membrane was applied to provide a minimum dry film thickness of 2mm which equates to 2.8 Kg/m2. We use airless spray equipment specifically developed to meter, mix, and apply the product. As the waterproofing membrane is to protect a road bridge, a tack coat (coloured orange) is applied to ensure a strong bond with the asphalt road surfacing.

Execution

The work was carried out between March and August 2020 in two phases. Phase 1 covered the eastern carriageway and Phase 2 the western carriageway which allowed the bridge to remain open at all times under traffic management conditions.

Phase 1 work commenced in March 2020 and Phase 2 commenced in the first week of June. The work was completed on time by the end of August 2020.
A particular challenge to the programme was the Covid 19 pandemic but by following Government guidelines and protocols the company was able work throughout this difficult time. A minor complication resulting from the pandemic meant that to ensure social distancing a walkway had to remain open on the west side of the bridge. This became a relatively minor third phase once the bulk of the work on the west carriageway was completed.

The result

The work was completed on time and on budget to the satisfaction of the main contractor and the client. The project was delivered during a difficult period in the UK when day to day life was significantly disrupted.

Metrail are now recognised as one of the leading specialist contractors in the sector with an excellent track record working with tier one contractors.

“We had a fantastic run of dry weather which is excellent for installing the waterproofing system. This meant that Phase 1 on the East side of the bridge was completed ahead of schedule. We were able to work throughout lockdown, making sure that operations were fully compliant with UK Government guidance for safe working practices in relation to social distancing.”

Martyn Sherwood, MD Metrail Construction

Impressions from the London Bridge Refurbishment

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