A recent trip to have another look at Merseyside Tramway Preservation Society’s Birkenhead Taylor Street HQ brought this bridge into view whilst riding on a preserved/rebuilt Wallasey tram.
The bridge is of the bascule type that was placed at various locations around Birkenhead Docks and it is impressive. The wikipedia page below has some information about it:-
en.wikipedia.org/wiki/Egerton_Dock
The photo is amongst my Flickr shots at:-
www.flickr.com/photos/86659476@N07/