COMPARISON OF RAILWAY BRIDGE SPECIFICATIONS. 



208 



TABLE XIII. 



SPACING OF GIRDERS AND TRUSSES 



7. Live Loads. Data for live loads are given in Table XVI. The type of engine is given 

 in the second column and the weight in thousands of pounds of a single engine without tender 

 is given in the third column; the special loadings and the spacing of the loads are given in the 

 fourth and fifth columns; the impact formulas are given in the sixth column; the allowable tensile 

 stresses are given in the seventh column, and the equivalent loading is given in the last column. 

 The equivalent loading is found by multiplying the loading in the second column by 16,000 and 

 dividing by the allowable tensile strength. The present standard loading on trunk lines is Cooper's 

 E 60 loading. 



The C. M. & St. P. Ry. uses E 60 followed by a train load of 7,000 Ib. per lineal foot of track 

 on ore roads; while the Duluth & Iron Range R. R. uses E 60 followed by a train load of 8,000 Ib. 

 per lineal foot of track. 



In a paper entitled "Rolling Loads on Bridges" published in Bulletin No. 161, Am. Ry. 

 Eng. Assoc., November 1913, Mr. J. E. Greiner, Consulting Engineer, has tabulated the live 

 loads of 39 railroads, including all but one of the roads in Table XVI. Of the 39 roads thirteen 

 are building bridges equal to E 60; four equal to E 57; seven equal to E 55; one equal to E 53; 

 ten equal to E 50; two equal to E 47; one equal to E 45, and one equal to E 65. 



Of the 39 roads considered 26 roads use the impact formula of the Am. Ry. Eng. Assoc.; 

 and 24 roads use a tensile stress of 16,000 Ib. per sq. in. The highest tensile stress is 18,000 Ib. 



