Hammersmith Bridge in London closes after propagation of existing cracks

The Hammersmith Bridge in London was completely closed after authorities found that existing cracks have been propagating during the summer.

Hammersmith Bridge spans over the River Thames in West London. It is a suspension bridge that was constructed in 1887 measuring 210 meters in length and 13 meters in width. A great proportion of its framework was built using wrought iron, an alloy with low carbon concentration that is vulnerable to shattering.

The structure has experienced structural deficiencies associated with the traffic low that it has to bear. Certain structural modifications have been applied to the structure so that it can withstand the increased loads, however, it has been closed several times for repairs.

Microcracks were initially discovered in the structure back in 2014. The conditions were monitored and the bridge was closed to motorists in 2019 after "critical faults" were detected by London officials. In particular, authorities discovered cracks in the structure's pedestals and decided to allow only pedestrians and cyclists to cross it until certain measures are taken.

Nevertheless, by August 13, 2020, the bridge was indefinitely closed to cyclists and pedestrians as it was found that those cracks have been propagating, thus, the integrity of the structure is deteriorating. Moreover, no vessel is allowed to pass under the bridge. “Public safety must always come first, so we fully support the council’s decision to close Hammersmith Bridge based on expert technical advice," a Mayor of London spokesperson stated.

Engineers reported that the cracks propagated as a result of intense heatwaves that recently struck London. In particular, as of August 12, the temperatures reached more than 34°C in London for 6^th consecutive day. "The deterioration in the structure was exacerbated by the recent heatwave which caused cracks to significantly increase – despite measures taken to mitigate the heat. The bridge will remain closed until the engineers are confident that it is safe to re-open to pedestrians and river traffic," a statement from Hammersmith and Fulham council mentions.

Contractors attempted to prevent the crack propagation by watering the bridge so that its temperature remains relatively low but the endeavor was not successful. 

Experts have established an advanced network of sensors and monitor the conditions of the structure in real-time.

According to officials, the structure needs to be repaired so that it can be operational again. The repair works would last around 3 years but, the main funding has not been secured yet.

Nevertheless, Transport for London, a governmental organization handling the transport system in Greater London, has managed to offer 33.4$ million for the restoration of the iconic bridge.

Sources: BBC, Standard, Timeout