"The Duddeston Viaduct" this is a new one on me there has never been a viaduct at Duddeston the viaduct before Duddeston is known as Vauxhall Viaduct and is on a different line to the one you are referring to.Dek
Dek The Vauxhall Viaduct was completed in 1839 to service Curzon St Station the Duddeston Viaduct was supposed to link with the lines to New Street but because internal politics and bickering it never came to fruition and was abandoned when New Street became Birminghams main station. The Viaduct terminated in what is now the Council Depot in Montague St