Tinsley Bridge – Sheffield 1968, Why are the stainless Steel Macalloy bars black?

Tinsley bridge Sheffield, the UK's first two-tier road bridge

Tinsley Bridge was completed in 1968 and was the first, two-tier road bridge in the UK. In 2006 the viaduct required extrensive strengthening, which took three years to complete and the construction was complex.

One day the police visited Macalloy, requesting our help. They explained a man had climbed the Tinsley viaduct during the night and attempted to steal the stainless steel Macalloy bars supporting the structure. The thief had cut into the bar in his attempt to remove it. Although his efforts failed, it left the bridge potentially vulnerable, and the viaduct had to be closed.

The Macalloy engineering team were asked if they could replicate the damaged bar under factory conditions, checking its structural properties. All the damaged bars were eventually replaced but, this time, they were all painted black to deter any potential thefts in the future.

Tinsley bridge Sheffield, the UK's first two-tier road bridge
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