OPB makes a crucial point about political influence. Personally I think the worst case is when honchos prevail upon the "experts" to jigger their studies and reports to favor a a policy decision that already been made. The @#$%& is in the details - how much weight do you assign to the various pros and cons of the different options.

Problem is theses engineering studies and cost estimates are really expensive, which puts the public at a real disadvantage when it tries to make common sense objections. It takes money to keep the big money honest.