@Setanta,
As reported by the NOAD, into has the following meanings:
expressing movement or action with the result that someone or something becomes enclosed or surrounded by something else. (Cover the bowl and put it into the fridge.)
Doesn't sound like it pertains to a road.
expressing movement or action with the result that someone or something makes physical contact with something else. (He crashed into a parked car.)
Doesn't sound like it pertains to a road.
indicating a route by which someone or something may arrive at a particular destination. (The narrow road that led down into the village.)
Doesn't sound like it pertains to a road.
indicating the direction toward which someone or something is turned when confronting something else. (with the wind blowing into your face)
Doesn't sound like it pertains to a road.
indicating an object of attention or interest. (a clearer insight into what is involved)
Doesn't sound like it pertains to a road.
expressing a change of state. (a peaceful protest which turned into a violent confrontation)
Doesn't sound like it pertains to a road.
expressing the result of an action. (They forced the club into a humiliating and expensive special general meeting.)
Doesn't sound like it pertains to a road.
expressing division. (three into twelve equals four)
Doesn't sound like it pertains to a road.
informal (of a person) taking a lively and active interest in something. (He's into surfing.)
Doesn't sound like it pertains to a road.
onto means:
moving to a location on the surface of something. (They went up onto the ridge.)
Sounds like it could pertain to a road.
moving aboard (a public conveyance) with the intention of traveling in it. (We got onto the train.)
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Following your idea, it would be correct to say that you “
get out of I-75 and turn
into North 41.” I’ve never heard anyone say that. And that’s because they say that you “
get off I-75 and
onto North 41. And the reason they say that is because it makes more grammatical sense than getting
out of and
into roads.
Ever wonder why cops never say, “The suspect then got out of Center Street and turned into 4th Street”? Conversely, have you ever wondered why the cops always say, “The suspect then got/turned off Center Street and onto 4th Street”? It’s because they understand the difference between into and onto.