“One quarter of all steel bridges in the US may fail by 2040”

A quarter of all steel bridges in the US may be at risk of failure in the next 20 years as a result of poor maintenance and global warming, according to research carried out by engineers at Colorado State University and published in the latest edition of the science journal PLOS ONE.

The report, by Hussam Mahmoud and Susan Palu of Colorado’s Department of Environmental Engineering, modelled the effect of rising temperatures on 90,000 steel bridges across America.

The engineers looked at the effect of inadequate maintenance and increased temperature on bridges’ expansion joints – small components whose failure can lead to structural collapse.

This survey, the first large-scale examination of the effect of neglect and rising temperature on steel bridges, found that there was a widespread danger of failure when joints are clogged with dirt and debris and then exposed to the increased thermal stress caused by climate change, since the clogging would prevent the joint from expanding.

They found that a quarter of were at risk of a failing before 2040, and almost half by 2080. Almost all bridges will collapse by 2100. Those located in the northern US are the most at risk, as this is the area that is expected to experience the greatest change in temperature, with North and South Dakota being the most vulnerable states.

The researchers note that their findings suggest that a huge maintenance effort would be required to preserve the bridges, and they suggest action to prioritise the structures most likely to fail.

Image: The bridges of America (

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