When giving directions I've notice that articles are omitted in the interest of brevity, i.e. cross street at light, turn into ally, park behind house.

Same goes with other directions/instructions, i.e. in cooking we'll most often see "fold flour and sugar into shortening" rather than "fold THE flour and THE sugar into THE shortening."

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Never cross the street v. never cross a street.

This is how I see it...The first refers to a specific street (the one in front of the person you are talking to). The second refers to every street.