Most structural failures are the result of an error made by one to the people involved in the great number of steps between the original idea and the completion of the final structure. However, in some cases the error was "built-in" in the drawing, either from faulty design or faulty representation of the intended design. The possibility of a gross error in design actually getting into the construction stage is indeed remote when you consider all of the controls- design, estimating, detailing, field supervision, construction- through which a job must pass. Yet the possibility still exists. Concrete designs need more than a numerical checking. A cursory examination of the design drawings by an experienced engineer or constructor will often show up any gross errors in design. It is usually the small items such as the secondary stresses that occur from volume or shape change that prove the most troublesome. Twenty-five years ago when the free support moments were split as desired into positive and negative factors the arbitrary assumption of the location of the points of inflection often resulted in cracks since the assumption was not in compliance with actual relative stiffness of the contiguous members. The reduction in mathematical processes introduced by the Hardy Cross moment distribution procedure eliminates much of this type of local failure, but only when realistic stiffness rations are determined. It is important that details follow a recognized standard and that everyone use the same symbols and notation. In slabs with straight steel in top and bottom, it has been found expedient and economical to prepare separate detail sheets for the top steel and for the bottom steel. The layers are separately installed and this procedure eliminates all possible errors or misunderstanding.