Hammersmith Bridge: refurbishing a London icon

Author: Rufus Foster

Date published

27 November 2022

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Hammersmith Bridge: refurbishing a London icon

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Author

Rufus Foster

Date published

27 November 2022

Author

Rufus Foster

Rufus Foster, Senior Bridge Engineer at Mott MacDonald, explains how his team is repairing fractures and strengthening Hammersmith Bridge as part of a major restoration of this heritage landmark.

A beacon of the Victorian era 

Hammersmith Bridge is one of the most iconic bridges in London. It’s a Grade II listed chain suspension bridge constructed from wood and wrought iron, and ornately adorned to show off the splendour of the Victorian era. 

The bridge was designed by famous 19th century civil engineer Sir Joseph Bazalgette. Built in 1887, it’s one of the oldest suspension bridges in the world and still forms an important part of the London transport network. 

The suspension is held in place by impressive cast iron pedestals. These are suffering from structural defects as the weight and volume of traffic the bridge supports has increased over the years.  

Ensuring ageing transport infrastructure is maintained safely is a complex challenge and needs advanced structural engineering expertise. Often, there is little precedent for solving the problems posed. This requires engineers to develop new and individual refurbishment solutions to ensure a structure is safe and useable, and its important heritage features are preserved.  
 


Uncovering major defects 

At Mott MacDonald, we were engaged to undertake the inspection, monitoring, testing, detailed structural assessment and feasibility design for the strengthening and refurbishment of this important heritage bridge. We identified a number of sub-standard components. These will be addressed as part of the major Hammersith Bridge Restoration Project launched earlier this year. The major refurbishment works will include strengthening and remediation of the chains, hangers, stiffening girders, decking system and articulation.  

However, we also uncovered a number of major critical defects. Given the risk to public safety, these discoveries have resulted in significant restrictions to the bridge use and mitigation procedures being put in place in recent years. The critical defects must first be remediated to stabilise the bridge before the rest of the refurbishment works can begin. 
 

How the suspension works 

At each end of the bridge, the suspension chains are deviated through saddles before descending through tunnels where they are locked off and secured. The deviation saddles are supported on the bridge’s large cast iron pedestals via steel roller bearings. The rollers have deteriorated over time and completely seized up. This seizing has generated large restrained horizontal forces in the pedestals, which in turn has caused significant overstress. Major fractures have appeared through the cast iron support structures. 

Stabilising the bridge has presented a significant challenge in providing an efficient design while maintaining public safety, minimising disruption and reducing the impact on historic features. 

 

Strengthening the bridge for future generations 

Our team at Mott MacDonald has developed a suite of solutions to solve the unique problems presented by this bridge. We will strengthen the saddles and pedestals before the seized rollers are replaced with new elastomeric bearings. These modern bearings will help the load on the bridge to shift slightly, preventing future fractures as the bridge is subjected to the stresses of daily use.  

Due to the challenging constraints, the works require a complex sequence of jacking operations, novel construction processes, bespoke parts and materials. The internal voids of the pedestals have already been infilled with steel fibre reinforced self-compacting concrete, and works are progressing to install temporary and permanent steelwork in advance of jacking.

We hope the structural refurbishment and rehabilitation of Hammersmith Bridge will demonstrate how cutting edge engineering can preserve important historical transport infrastructure and secure it for future generations.