PUPPY REFUSES TO WALK！

I have a 6 month old rough collie that is mostly such a well behaved happy pup but recently has developed a fear of walking past our street! We live on a suburban street with not much traffic but as soon as we walk out of our street there is a main road with a bit more traffic. Puppy will not walk anywhere near the main roadall of a sudden! He just immediately plops his butt down and pulls backwards, we tried luring him with treats and toys but both did not work. We are guessing he’s scared of the traffic noises as he’s happy to walk in any other situation (ie when we take him out to the park in a car)

Has anyone had this problem before and managed to get their puppy to walk?