I also have that bridge in the original box. I don’t have any photos of it but I thought it had been discussed on here before. Anyway here’s a link to photos and more info about it and the manufacturer on Graeme Eldred’s very useful website: http://www.binnsroad.co.uk/railways/hh/index.html The TCA Quarterly issues in which it was discussed are also identified in that link.
H&H Manufacturing was or maybe still is in Pittsburgh, PA (my home town). They made a few train items and according to a database of Pennsylvania companies there may still be a company by the name of H&H Sales & Manufacturing located at the same address in Pittsburgh that is shown on the box in one of the photos in that link above.
HTH,
Bill