One of the better discussions on "article usage", (though even this pdf makes one's hair hurt,
).
From my interpretation of the "rules", it is acceptable to use "the 405"...I always noticed the southern
LeftCoast residents propensity to say, "take the 405"; a colloquialism, I presume.
The RightCoastGang does not talk like that.
English grammar is difficult, and always evolving whether the strict grammarians like that evolution, or not.
http://www.rpi.edu/web/writingcenter...ticles_ESL.pdf