Guidance summary
Check the height and usable width beneath a bridge
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Bridges with clearance below 16 feet 6 inches, about 5 metres, are normally signed. This convention is not a guarantee that a missing or damaged sign makes passage safe. A red circle prohibits overheight vehicles. At an arch, the marked height applies between the indicated limits, not beside the kerb. Height warnings can also appear on direction signs before the bridge.
Source: Check the height and usable width beneath a bridge
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