If you’ve ever suffered a bridge closure or a local main road being out of action, you’ll know the pain of ongoing diversions, delays and traffic issues. That’s what residents of both Hammersmith and Barnes have been putting up with, after their Victorian suspension bridge was closed for structural monitoring and repairs.
But with microcracks in its cast iron pedestals, meaning the pedestals could potentially shatter like glass, the closure of Hammersmith Bridge was clearly a better option than risking collapse. Work has now begun to stabilise the bridge, but it’s an interesting lesson in the importance of ongoing monitoring and maintenance of municipal structures.
Had the council not asked the question, “How safe is Hammersmith Bridge?” back in 2015, there’s a possibility that the bridge could have suffered a catastrophic collapse while in use, hitting river traffic below and taking people, cars and bikes with it.
Fortunately, asking the question led to Hammersmith and Fulham Council bringing in specialist engineers from around the world, who had the knowledge and experience to carry out a survey of the unique structure. As those engineers carried out their investigations, “peeling back” layers of the bridge, they found serious levels of untreated corrosion, leading to the bridge’s initial closure to motor traffic in April 2019, and to all traffic in 2020.
The 250m-long bridge is now carefully monitored and controlled using heat equipment that controls the bridge temperature. Sensors flown in from the US are positioned all over the bridge – for 24-hour monitoring.
The bridge has been open to pedestrians again since July 2021, after the monitoring systems were put in place. Bikes and scooters may also cross if they are wheeled rather than ridden. The scooter companies have reset their scooters so they can only be wheeled across, and river traffic is allowed to pass beneath the bridge.
Phase one of the bridge stabilisation project is now underway, at a cost of £8.9m. For phase two, which will allow the bridge to reopen to motorists, an innovative double-decker solution has been proposed by Foster + Partners and specialist bridge engineers COWI.
This would involve a temporary truss being laid over the existing carriageway, allowing cars and buses to cross, and is expected to cost £100m. This is £40m less than a previous proposal. At first, pedestrians and cyclists would use the upper level, and the lower level would act as a construction site, enabling workers to access the deck of the bridge.
This proposed phase two could see the bridge reopening to all traffic in autumn 2022 and the full restoration completed in 2023.
Before phase two can go ahead, Historic England needs to approve the work to the Grade II listed bridge. The plans include lifting away the elements of the bridge that need to be repaired and transporting them via barge to an off-site facility for repair and restoration.
The initial stabilisation work is expected to be finished by October 2022 and the bridge will remain open to foot traffic during most (but not all) of this work.
Hammersmith Bridge is only five years younger than Brooklyn Bridge in New York, so it’s great to see it finally being restored, and hopefully back to being a fully functioning route within the next year or so. It’s a good example of the need to monitor structures for safety, and to maintain them properly over time. It’s lucky that someone questioned whether this was being done in the case of this bridge.
Meanwhile, if you need assistance with the structural elements of an upcoming project, please do get in touch.