Commendation 2021

Award for
Construction Innovation

Project Description

A project to rehabilitate the 170-year-old Bazelgette sewer without the need for rail or road closures. The project boasts impressive savings of £23m and 26,443 tCo2 against the client’s original business plan. With a design life of 120 years, it eliminated catastrophic failure of the asset and associated disruptions and risk to the public.

Judge’s comments

In response to unique engineering challenges and a highly constrained site, this project involved strengthening an old sewer from inside the existing structure located above an operational tunnel and below a heavily congested road junction in Central London. The clever design and construction solution provided for a modular steel truss structure which could be assembled inside the sewer.

To allow access through a single 600mm x 750mm manhole, all project components were specifically designed to be as lightweight as possible, modular, and less than 2m in length. The project was executed with every component fitting together with millimetre precision.

The judges were impressed with how health and safety considerations were constantly embedded within the project using cutting-edge technological monitoring and alarm systems; and how the data collected informed the design. The design team were able to accurately assess interfacing structures, minimise space limitations and reduce construction time inside the confined space sewer. To minimise risk both Virtual Reality and Augmented Reality visualisation techniques were adopted to familiarise the construction team with the environment.

Project overview

Structural Designer

  • Transport for London

Client Name

  • Transport for London


  • London, UK


  • NA

Principal Contractor

  • Skanska UK

Key Contractors

  • Thames Water Commissioning Authority – Key Contractor 

    Transport for London Commissioning Authority (railway) – Key Contractor 

    Stantec – Lead Designer

Year Submitted

  • 2020