SK53
Information about everything on OSM is provided by tags. The access ones are usually a transport mode followed by a value such as yes, no, permissive, destination.

In this case the gates preventing people driving off the swing bridges are treated as barriers preventing access, so (hopefully), adding access=yes to each of the gates should resolve the issue.

It might take some time for the router to update. Also the whole area of routing and barriers is complex: https://forum.openstreetmap.org/viewtopic.php?id=58238

I will add the tags & then we can wait and see.