As someone who's passed over the King Edward VII bridge only twice, even I gathered it isn't that or the Tyne Bridge.
As for the bridge over to Anglesey, traversed that in July and I don't remember a road bridge like that alongside the railway line - even in pitch-black conditions I think I'd have spotted a structure like that.
Sorry, haven't a clue but thought I'd help in ruling those two out - the Britannia Bridge, remind me where that is again... it sounds familiar but whether or not that's the answer...
100% Runcorn! If Yorkie says it's not - I'm gonna argue with him! My mum's mate used to live in Runcorn and I went over it many a time. The bit on the right is road bridge and used to be red. The station is just out of view to the bottom of the image. The bridge has castle-like turrets at each end of the riverbank (Mersey).