Here is my naive query for bridges:

    SELECT ?item WHERE {
    	?item wdt:P31 wd:Q12280.  # Item's type is: bridge
    }

**Problem**: It only returns a small fraction of all bridges, because railway bridges (and all other subclasses of "bridge") are not counted.

How to retrieve all items, including sub-classes? It MUST be with [SPARQL][5].


  [5]: https://query.wikidata.org