Officials loyal to Gov. Chris Christie of New Jersey went to elaborate lengths to make it appear that the September closing of lanes leading to the George Washington Bridge was part of a traffic study, even though their private communications suggest the move was purely political, according to documents released on Friday.

The documents also show a concerted effort to keep their true motivation hidden, including the insistence by one official of the Port Authority of New York and New Jersey in an email that communications about the matter should not be conducted by email or discussed publicly.

Among the documents was a PowerPoint presentation prepared after three days of snarled traffic, titled “EARLY assessment of the benefits of the trial.” The conclusion: “T.B.D.” (To be determined.)

Ultimately, the traffic diversion, in Fort Lee, N.J., led to four mornings of gridlock, months of investigations into whether the move was a blunt display of political payback and what has become the gravest challenge to Mr. Christie’s political career, after it was revealed that a top aide was intimately involved in the matter.