Thank you for that information. I am sorry for the delay, computers are great until they have problems!
Dogs will do what works for them and for dogs that are fearful acting out works. So if you put yourself in the dogs shoes, his barking and carrying on makes the other dogs go away eventually. He does not really know that you will keep him moving or that another dog is going to pass anyway, he feels it is his barking and acting out that causes the other dog to be removed from his presence.
The key to helping a dog build confidence is to train him daily using a positive obedience method. For street walk when the dog is walking with you and you know there is a known issue that is about to occur you would use your Leave it and then a heel command. Thus this distracts your dog to something that it will be rewarded for rather than the acting out. When we have our dog's focus this gives them little to act out about because their mind is on us awaiting the next command. This is why we first give the dog a leave it, this tells the dog what you don't want it to do, then we give a heel which tells the dog what it can do instead that will yield it attention positively.
I am going to direct you to links for positive obedience training and you want to start in a non distracting place such as the home then gradually build to more distracting places once you see that the dog is listening to you. At this point I would just take him out for a potty reason and not go too far from home because to do this you are setting him up to fail as he only knows one way to behave when he comes upon a strange dog. We want to set him up for success.
I would use special dog treats for inside the home and non distracting places but up that ante to hot dog slivers or chicken slivers when you take it to the street.
I would do behavior adjustment training with him when you get to the street and I will direct you to a link for that as well which will help you to understand how to do all of this on your own.
Clicker training/positive method training/ print off
video’s to see how clicker training is done, scroll down to videos http://www.clickertrainusa.com/clicker-training-videos.htm
clicker maintaining focus http://www.clickertraining.com/files/auto-eye-contact.pdf
Training method BAT http://empoweredanimals.com/