Lacb, Manor Mount is a wide road. Problem is Waldenshaw narrows in the middle making it difficult for cars to pass and St. David's is very narrow.
As I have already said, the Highway Planners decided it was a good idea to make it one way, hopefully they have qualifications in highway planning so offer a better insight into traffic than you and I can offer.
Also, remember, you cannot please all of the people all of the time.