. The elements of railroad engineering . out ? RAILROAD CONSTRUCTION. 1329 (900) How should they be mapped and their contentscalculated ? (901) What are grade stakes ? (902) The grade at a station is ft.; the height ofinstrument is ft. ; what should the rod read at thestation, for the roadway to be at grade ? Ans. ft. (903) What does the term ovcrJiaul signify ? (904) What are the two important factors in the locationof a bridge ? (905) What is the meaning of the term skew as appliedto bridges ? (900) Describe a method of making a direct measurementof a bridge span ? (907) Let
. The elements of railroad engineering . out ? RAILROAD CONSTRUCTION. 1329 (900) How should they be mapped and their contentscalculated ? (901) What are grade stakes ? (902) The grade at a station is ft.; the height ofinstrument is ft. ; what should the rod read at thestation, for the roadway to be at grade ? Ans. ft. (903) What does the term ovcrJiaul signify ? (904) What are the two important factors in the locationof a bridge ? (905) What is the meaning of the term skew as appliedto bridges ? (900) Describe a method of making a direct measurementof a bridge span ? (907) Let A B (see Fig. 19) be the center line of the pro-posed bridge, and B C the base line, the length ofwhich is ft. The angle A is 40° 55; the angle Cis 43° 22; required, thelength oi A B. ^ Ans. ft. (908) What are someof the considerationswhich determine thenumber and location ofthe piers of a bridge ? (909) When the riverbed is of rock, or firmsand, or clay, how arepier foundations pre-pared ? (910) What are coffer-dams ?. Fig. 19. (911) A side of a cofferdam is 40 feet in length and 11feet in height; the water is 10 feet in depth; {a) what isthe total water pressure against the side of the dam ? {l)) 1330 RAILROAD CONvSTRUCTION. What is the moment of the water pressure about the innertee of the dam ? j, j {a) 1-25,000 lb. ■ ( (/;) 10,471 (912) If the filling of the dam is 5 feet in thickness,11 feet in height, and weighs i:)0 lb. per cu. ft., (a) what isthe moment of resistance of which the filling alone opposesto the water pressure ? {I?) What is the factor of safety ofthe dam? .^^ j (a) 17,875 ■ (d) (913) Under what conditions would you construct a pilefoundation ? (914) How would you protect the foundation from thescour of ti\e current ? (915) What stone is best suited to bridge foundations ? (916) In building bridge piers, what are the differentmaterials used for backing ? (917) Under what conditions are pneumatic foundationsemployed
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
