The sentence "A blind man crossing the road" doesn't have a clear subject and predicate. It is an example of a sentence fragment, which is an incomplete sentence that lacks a subject, a predicate, or both.
However, if we were to add a verb to the sentence, it could be revised to something like "A blind man is crossing the road." In this case, the subject is "a blind man" and the predicate is "is crossing the road."