Complex sentence: The first bridge at Haydon Bridge was built in around 1309, but following the flood of 1771, it had to be rebuilt in 1776; following surveys it ceased to be used by cars and converted to foot bridge use only in 1970.
Split into simpler sentences: The first bridge at Haydon Bridge was built in around 1309, but following the flood of 1771, it had to be rebuilt in 1776. Following structural surveys it ceased to be used by cars and converted to footbridge use only in 1970.