According to this BBC Article, "a massive amount of data and expert analysis on how and why the twin towers of the World Trade Center collapsed after being struck by two hijacked jetliners in the 11 September attacks may never be released"-- this due to the fact that the documents were collected for the purposes of litigation. The documents are already under court seal, so they are not open for inspection by the public.

Moreover, everyone involved in compiling the data is bound by some form of non-disclosure agreement, so they cannot offer any information. Unless the court breaks with precedent, if there is a settlement, the documents could remain under seal in perpetuity or destroyed.

And what is the lawsuit about, one might ask?

The court battle is between real estate executive Larry Silverstein, whose companies owned a lease on the property, and a group of insurance companies.
Mr Silverstein claims that the plane crashes on 11 September were two separate terrorist incidents, which would make him entitled to $7bn, instead of the $3.5bn insurance firms are willing to pay out.

I myself would argue that the two crashes were separate actions taken in furtherance of a single act; namely the destruction of the entire tower complex. Thus, since neither action alone could have destroyed both towers, both were necessary to achieve the goal, and thus should be considered, for purposes of the court, as a single "incident."