Client
TFL (FM Conway)
Value
£700k
Sectors & Services
Highway Structures Rail Concrete Repair Condition Surveys Corrosion Control Cleaning & Preparation Projects Projects
Drewstead Road Bridge in Streatham Hill, within the London Borough of Lambeth, carries the B221 over the main railway line just west of Streatham Hill Station. Constructed in 1968, the bridge comprises precast, prestressed concrete beams supported on circular columns and crosshead beams. It is a vital local transport link, accommodating bus routes, pedestrians, heavy goods vehicles and daily commuter traffic.
Detailed investigations undertaken in 2012 identified deterioration to both the superstructure and supporting elements. To safeguard this critical asset and maintain safe operation over a busy railway corridor, a comprehensive refurbishment scheme was developed to extend the bridge’s service life by at least 25 years.
Services undertaken
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Structural condition surveys and testing
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Hammer testing and making safe
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Cover meter surveys
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Chloride screening and carbonation testing
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Development of repair options and technical appraisal
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Concrete repairs to beams, columns and crosshead beams
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Installation of impressed current cathodic protection system
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Detailed design development and methodology planning
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Fully enclosed hoarding installation to create a green zone
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Works undertaken adjacent to an operational railway
CRL’s involvement commenced with a targeted programme of investigative surveys undertaken by CRL Surveys in December 2012. These works included hammer testing and making safe of defective areas, cover meter surveys to assess reinforcement depth, chloride screening and carbonation testing to establish the mechanisms driving deterioration. The findings enabled CRL to present the client with a range of repair options, clearly setting out technical implications, durability outcomes and cost considerations. The agreed solution combined conventional concrete repairs with the installation of an impressed current cathodic protection system to the portal crossheads, addressing both visible damage and ongoing corrosion risk.
Following survey and option appraisal, detailed design was progressed through close collaboration between CRL, FM Conway and Free4m. Particular emphasis was placed on constructability, safety and minimising disruption to both rail and highway users. A key innovation was the agreement that all works within the railway corridor could be undertaken inside a fully enclosed hoarding constructed at platform level. This approach created a secure green zone, removing reliance on engineering hours possessions and eliminating the risk of late cancellations that often affect rail interface projects.
Concrete repairs were undertaken to the superstructure, columns and crosshead beams in accordance with industry standards, reinstating structural integrity and preparing substrates for long-term protection. The impressed current cathodic protection system was installed to the portal crossheads to control reinforcement corrosion and enhance durability. The fully enclosed hoarding also allowed the works to proceed through the winter months of 2014, with Streatham Hill Station remaining fully operational throughout. Despite being delivered over an active mainline railway, within a residential area and on a busy trunk route, the project was executed efficiently through robust planning, coordination and proven technical delivery.
"Early contractor involvement, a pro-active client and a forward thinking engineer also contributed to the ensuring that the structure will withstand the ravages of time and the elements for a further 25 years."
Tony Parasram | Director | Free4M Consulting
The refurbishment of Drewstead Road Bridge delivered benefits well beyond the immediate repair works. By combining targeted concrete repairs with impressed-current cathodic protection, CRL addressed existing defects and future corrosion risk, significantly improving durability and reducing long-term maintenance requirements.
The collaborative development of a green zone working environment protected rail operations, ensured passenger safety and maintained operational continuity throughout the programme. This approach supported the client’s wider asset management objectives, extending the bridge’s service life by at least 25 years while minimising disruption to the local community.
The project demonstrates CRL’s expertise in structural repairs UK, delivering resilient, sustainable solutions through careful planning, technical excellence and dependable workmanship.
