Norfolk County Council have just made their picture catalogue searchable on line.
Searching for 'railways' brings up 270 photographs of railway interest in Norfolk.
https://norfolk.spydus.co.uk/cgi-bin/spydus.exe/PAGE/PICNOR/BIBENQ/9412560/1
I tried various search terms for my interests, however, this general term produced the most photographs.
Hope this helps anyone needing research information.
Just done another search for 'trains', came up with 118 pictures.
Norfolk County council Also do historic maps, which may be useful if looking for information on a particular site http://www.historic-maps.norfolk.gov.uk/ (http://www.historic-maps.norfolk.gov.uk/)