There have been several independent validations of NIST's own models, and at least four totally independent simulation efforts.
NIST describes in the report who the model creation and checking were contracted to, and the contract announcements are on their awards page
. The NIST report also references how their models stack up against the MIT
model (relatively simple) and Weidlinger Associates
models (fairly sophisticated), as described in chapter 9.12 of NIST NCSTAR1-2B
. A third study was done by Exponent Failure Analysis Associates
(formerly known as Failure Analysis) for Silverstein's insurers, and was thus actually hostile to the conclusions of the Weidlinger study. There is also the work of Purdue University
, and probably several other efforts that I haven't even heard about.
Of the many models used in the different steps, the most difficult is probably the fire progression. NIST is still developing its own software for fire modeling (called FDS, or Fire Dynamics Simulator), and discusses in detail how it was validated in NIST NCSTAR1-5
. Fire modeling is tough, but on the plus side, the fire progression was partially observable from the ground, unlike the details of impact and core damage.
On the basis of this rich body of research, not to mention the depth of the NIST report itself, I'm extremely comfortable with its methods and conclusions. I also have a good grasp of the uncertainties in its model -- as there will be in any model -- and can defend the position that such uncertainties do not affect the overall conclusions of the report.
I suspect the primary reason for not releasing models, aside from the fact that nobody would be able to do anything with them, is that the model information is proprietary
. The element models could be reverse-engineered to produce a blueprint of the WTC buildings and a Boeing 767 aircraft. Both are the property of private companies, and the latter is probably export-controlled under ITAR, in part if not whole.
The members of the Truth Movement have not produced any reason why we should take them seriously, so I am quite happy to ignore their demands. If they were to set themselves up with a legitimate research institution, with competent researchers, funding, sign non-disclosure agreements and produce an information technology security plan, then they should be able to get access to the models. But not before.