Network Rail's largest-ever fine from the ORR was for what the regulator regarded as the poor planning and risk management that led to delays in work at Rugby, Liverpool Street and Shields Junction.
However, former rail regulator Tom Winsor said that no matter the size of the fine, it was impossible for the ORR to be effective against Network Rail in its current corporate form.
"The fact is that the accountability of Network Rail has been significantly diminished as a result of the displacement of shareholder equity," said Winsor.
"There are now no private investors to whom management is accountable, who will take real financial pain for poor performance or cost overruns. Circular fines are little more than a distraction, and no-one is being taken in by this."
The ORR fine will be taken out of Network Rail's budget and handed back to a general Treasury fund. As Network Rail is funded by the government, the investor in this scenario fails to lose out, rendering the ORR toothless, said Winsor.
He added that shareholder pressure was the best way to effect change, and cited energy, water and telecoms as examples of public focused industries running effectively in private hands, in addition to London Underground.
The ORR's report said: "Urgent steps must be taken to ensure that there is no recurrence of this kind of event."