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It is only within a few years that much attention has been given to detailing by bridge engineers; the old custom having been for the engineer to figure the diagram of stresses, or, as it was then called, the strain-sheet, and pass it over to a draftsman (too often a cheap one) to make therefrom the working drawings of the bridge, using probably some old drawings of another bridge as a guide for the detailing. Concerning the evil effects of such a course of action the engineer who does much inspection of existing structures can speak authoritatively. If questioned upon the subject, any such engineer will say that nearly all bridges which fail or which are condemned and removed, are deficient in strength of details rather than in strength of main members.
Some years ago the author had occasion to examine and report upon nearly all the bridges on two hundred miles of the main line of an important Western road, with the result that he found it necessary to condemn almost all of them. A few have since been repaired, but most of them have been taken out and replaced. In most of these condemned structures the detailing was so faulty that the bridges were gradually racking to pieces, and no amount of patchwork would have made them really serviceable. It is true that the main members were considerably overstrained by reason of the increase in rolling loads, but had the details been first-class the structures would have been standing today.
Just here it may be well to mention that the inspection of these bridges caused the author to establish for himself the
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