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As there has been almost nothing yet written concerning the way in which work is handled in a Consulting Engineer's office, the author has concluded to close this little treatise with a chapter on "Office Practice"; and as no two engineers pursue exactly the same methods, and as the author is naturally more familiar with his own than with those of others, he will deal herein solely with the established practice of his own office, which practice is the outcome of over ten years of special effort to secure the best possible results both expeditiously and economically.
LAYING OUT WORK.
This chapter being confined entirely to office-work, it will be assumed at the outset that all such field data as profiles, maps, plats of borings, etc., have been secured.
In bridge-work it is necessary to determine the following:
First. The Purpose for which the Structure is to be used.— This being settled, there ensues the fixing of the live load, the clearance between trusses, and the clear height above base of rail or surface of roadway.
Second. The Clear height between Standard High Water and the Lowest Part of Structure— If the stream be a navigable one, the minimum clearance will be regulated by the requirements of the War Department. In other cases the clear height will depend on the required elevation of grade of railroad or roadway, provided that the lowest part of the superstructure will never offer any obstruction to floating drift or ice during the highest floods. The minimum clearance should preferably be ten feet, and never less than five.
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