. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . iJi V TYPE Bj FROM 40 TO 70 FEET I TYPES OF PLATE GIRDER BRIDGES. C. M. & RY.(Dec. 1895.). (Zo face pays 2Q4:.) CHAPTER Vll. 231. Purpose and requirements. The object of the ballastis to transfer the applied lo?.d over a large surface; to hold thetimber work in place horizontally; to carry off the rain-waterfrom the superstructure and to prevent freezing up in winter;to afford means of keeping the t
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . iJi V TYPE Bj FROM 40 TO 70 FEET I TYPES OF PLATE GIRDER BRIDGES. C. M. & RY.(Dec. 1895.). (Zo face pays 2Q4:.) CHAPTER Vll. 231. Purpose and requirements. The object of the ballastis to transfer the applied lo?.d over a large surface; to hold thetimber work in place horizontally; to carry off the rain-waterfrom the superstructure and to prevent freezing up in winter;to afford means of keeping the ties truly up to the grade line;and to give elasticity to the roadbed. Thi^ extremely con-densed statement is a description of an ideally perfect value of any given kind of ballast is proportional to theextent to which it fulfills these requirements. The ideallyperfect ballast is not necessarily the most economical ballastfor all roads. Light traffic generally justifies something cheaper,but a very common error is to use a very cheap ballast when aemail additional expenditure would procure a much betterballast, which would be much more economical in the long run. 232. Materials. The materials most commonly employed aregravel and broken stone. In many sectio
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
