
Bit of a funny age 5 months. My Border Collie decided she didn't like traffic as a pup, not scared but over excited and decided to chase. I decided it wasn't worth putting us both through the ordeal. I think you can make matters worse by over confronting the problem, especially with a sensitive breed like a collie.
I don't need to take her onto busy roads in our every day life, she is an angel in the car with busy traffic, I just drive to the woods and we are both happy. I tried all the distractions imaginable but once a collie has something in their head there is no stopping them.
She is now 15 months and not so bad, she will tolorate them in the daylight but still dislikes the headlights at night, wet roads made her worse too.
Personally if it is making her life miserable and no doubt yours and you don't need to walk her along the roads, I would give her a break at least for a couple of months.
Good luck
Sandra