If I say:
He was a bridgetender for some years.
How would I translate that into French?
The only specific French word I can remember for this occupation/activity is pontier, but it's extremely rare (French definition here). I think in most cases this would be described rather than named like that. A direct translation of your example could be simply:
Il était pontier depuis des années.
but in some specific contexts it might as well be one of these periphrasis:
If I had to make myself clear about it, I'd use gardien de pont or responsable de pont, the former if it's not too incorect with regard to the real job, the latter to be less precise, and less natural, but easy to understand.
If it's meant to be litterary, Romain's answer is very good.
Si je devais le faire comprendre plutôt que de verser dans le style littéraire, je dirais quelque chose comme gardien de pont, qui sonne pas mal, mais ne décrit pas forcément très bien l'activité, ou alors responsable de pont, plus vague, mais clair.