Unable to answer "What’s the height limit below the bridge?" – Alexander Graham Bell Parkway [403] (Motorway) – https://osm.org/way/24484952 via StreetComplete_ee 59.2:

Sign suggests that trucks over 6.5m tall should not drive under bridge. Could this indicate a height? This isn't the first time I saw that specific sign and measurement, so I'm concerned it's a standard sign and isn't specific to this underpass.