On April 1, 1982, the Federal Register announced that the Federal Highway Administration (FHWA) was adopting a document approved by the American Association of State Highway and Transportation Officials (AASHTO) which revises the chapter of the "AASHTO Interim Guide for Design of Pavement Structures 1972" concerning the structural design of rigid pavements.
In our judgment, and in the judgment of others in our industry with whom we've discussed the subject, the revised guide unquestionably imposes both technical and economic restrictions on concrete by suggesting that higher factors of safety be required on rigid (i.e. concrete) pavements without even a token effort to apply parallel logic to flexible (i.e. asphalt) pavements. If we are correctly informed, FHWA's adoption of the AASHTO revisions took place without any significant opportunity for input from the rigid pavement industry.
The AASHTO Interim Guide for Design of Pavement Structures has been around for years and has performed well. But if there was a need to increase safety factors, we believe there is credible evidence that the increase should have been mandated for flexible pavements and not rigid. So we believe the facts support the contention that this is a bum rap for concrete: the wrong material has been singled out and the entire exercise conducted with the unseemly haste that so often operates in tandem with injustice. Our industry is offered, for what it's worth, the reassurance that the higher safety factors now recommended for concrete pavements, but not for asphalt, are optional. It seems to us that the greatest injustices are almost always labeled as either optional, temporary, or merely recommended, until enough time has elapsed to establish that they are in fact none of these, but instead precisely what they appear to be.