How do you train your dog to properly cross at a cross walk?

I got a mastiff bordeaux she is about 7 months years old, I usually walk her every day. I do walk at a cross walk, but I would like to know if there is a way to teach a dog to walk across the street when no cars are ping. Is there a way? I am worried that the dog may get out, if she does, she can know how and when to cross. i'm just thinking worst case scenario.