I am amazed at your chutzpah; you say with the first breath the transportation plan didn't work, that you have doubts, then with the rest of your post that it did! That "it was one of a small number of clear victories"!

The Transportation plan did work. No one well read in the subject, or so much as glancing at a German primary source, could suggest otherwise. It worked so well, in fact, that it worked too well. It actually hampered the Allied advance. People forget that as part of the plan, there were coordinated ground attacks by resistance forces; some of the more enthusiastic of these went on and destroyed infrastructure the Allies wished to remain intact.

You also say yourself - the heavy bombers were backed up by significantly more accurate light-bombers and fighter-bombers. These worked in conjunction with ground forces. But even leaving aside the fully planned and equipped ground aspects of the plan, the fighter-bombers, esp, caused havoc - rockets and primitive missiles had been developed by this period, which could accurately and badly damage both moving columns of troops/cars/armour, but also railway sidings and other transport infrastructure such as cranes and heavy plant. You talk about attacking railways like the planes attacked the rails instead of the rollingstock, the refueling stations, the whole host of critical mechanics which a working railway requires to function.

The Bomber Barons, by this stage of the war - goodness me, this is red herring - yes, they remained convinced of the strategic value of their planes - but they also perceived that D-Day was going to be massive. Their contribution would be the bulk of the Transportation plan, and they lobbied hard for that. How sidelined would they have been afterward if they had ignored such a huge project? They released a huge number of planes to work both as an operational force and tactically with ground forces; their perceived contribution added value to the US calls to be made a separate service from the army, and diverted more resources their way.

You are a very clever man, and you've clearly read a bit on this topic, but the causal dismissal of a highly successful operational campaign, along with the internal inconsistencies of this post, both concern me.