This roughly means something like "just as" or "in accordance with" 요리책에 써 있는 대로 했더니 I made is according to my cookbook 예상대로 우리 팀이 이겼어요. Just as expected, our team won. Here's a Talk to Me in Korean lesson on it. http://www.talktomeinkorean.com/lessons/l8l18/

There are several meanings in it, 1. as a noun, "대로" means "main street" as you said, 2. as a linker, "as" meaning, "-ㄴ대로", e.g. 집에 도착하는 대로 전화해. = Call me as you get home. 3. as an adverb, "in the same way", etc,..... \^o^/