Description of Works

In 2019, an inspection of the Grade II-listed Teddington Lock Footbridges in southwest London revealed that the historic structures needed significant repairs.

Delivering Innovation

An inspection to the bridges found corrosion to the ironwork in both structures, as well as some small sections of damage to the concrete decks. Defects were also found on the main structure’s southern approach ramp requiring its complete replacement.

Phase 1 involved jet washing all the existing metalwork to remove salt water, followed by shotblasting to remove the old paint. This allowed all the corroded iron elements to be identified and replaced with new steel sections, before a new paint system was applied to protect the bridges in the future. Corroded areas included the underside of the bridge, where the concrete deck sits within iron troughs, channel sections that run between the bridge pylons, brackets connecting the troughs to the outer parapet, and sections of the parapets themselves.

Challenges and Solutions

For FM Conway, the biggest challenge was accessing all these areas without causing excessive disruption to people using the bridges.

With the footbridges being so essential to local residents and commuters, keeping them open while works were carried out was essential. They connect educational facilities – children who live in Teddington use them to go to school in Ham – and, as Ham doesn’t have a station, people cross the other way to use the station in Teddington.

The crossing facilitates around 7,000 pedestrian movements a day during the week and 9,000 at the weekend, so closing the bridge for the duration of the contract was not possible. FM Conway’s solution was to install a bespoke light-weight access system, suspended from the bridge using rope techniques. The access system was designed to fully encapsulate all the water, grit, paint, and debris. However, as the bridges were only designed for pedestrian loads, the team had to continually monitor any additional weight from the access system and repair activities.

“Careful planning was key to manage the loading restrictions on the two bridges. This was a complex sequence of works, and each access system had a maximum load, meaning the water from jet-washing and grit from blasting had to be removed instantly." Toby Allen, FM Conway Project Manager

The water was pumped into storage containers on pontoon and the shotblast system had two nozzles, one for blasting and one to vacuum, which instantly removed the grit and corrosion at source.

Outcomes

Phase 1 of the works was completed in January 2024, allowing the next phase of works to begin to bring the footbridges back to their former glory. The bridges have such a historical importance in the London Borough of Richmond-upon-Thames, built in the 1880s to carry pedestrians over the River Thames between Ham on the north side and Teddington on the south. Still an essential crossing point in the 21st century, the full refurbishment will allow the bridge to continue to serve the public on a daily basis.