Translation of 飞架 in 港珠澳大桥飞架三地
If the sentence was "港珠澳大桥高架三地", we can understand "高架" means "rise high"

Imagine the bridge was like a dragon, and this dragon flying high above the sea through three territories 

港珠澳大桥飞架三地 would mean "the Hong Kong-Zhuhai-Macao Bridge rises high above the sea like dragon fly through three territories"   

飞架 would mean "rises high and extends far"

飞架三地 would mean "rises high and extends across three territories"

Or 

simply "fly across" -- describe the bridge as a metaphorical dragon