The 'A' Frame bridge no. 249, crossing the River Wensum just outside Hellesdon. It was once part of the long-defunct Midland and Great Northern Joint Railway line, which closed in 1959. This strip of the former M&GN line is now a lonog-distance footpath and cycle route known as the Marriott's Way (itself named after William Marriott, the former chief engineer and manager of the M&GN).
Apparently no. 249 was one of only three 'A' framed bridges on the whole of the line, and is only a few hundred yards from the site of the demolished Hellesdon Station.