heads and bridge towers are. With option EASY_BRIDGES, all land
sectors are as well.
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-When a bridge falls, all mines in the sector are cleared.
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Ships can navigate under bridge spans that are at least 60% efficient.
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.SA "Unit-types, Ship-types, Plane-types, Nuke-types, Bridges, show, upgrade, Maintenance, Ships, Planes, LandUnits, Nukes, Sectors"