COST OF ERECTION OF STEEL BRIDGES. 437 



Erection of Structural Steel for an Armory.* The structural framework for the new armory 

 of the l : niviTMty of Illinois, consists of three-hinged arches having a span of 206 ft., and a o-ntrr 

 lu-inht of 94 ft. 3 in. The arches are spaced 26 ft. 6 in. centers and are braced in pairs. The total 

 weight of structural steel was 985 tons, and contained 15,400, J in. and 14,900, } in. or a total of 

 30,300 field rivets. The cost of erecting the structural steel, including field riveting was $9.55 

 |KT ton. The average cost of driving the field rivets was 13.1 cts. each. 



COST OF ERECTION OF STEEL BRIDGES. The cost of erection ordinarily includes: 

 (l) the cost of hauling the bridge to the bridge site; (2) the building of the falsework and the 

 placing of the steel in position; (3) the riveting up of the bridge, and (4) painting the steel and 

 the woodwork. 



Hauling. Transportation over country roads will ordinarily cost about 25 cts. per ton- 

 niilo, in addition to the cost of loading and unloading. In estimating the cost of hauling on any 

 particular job the length of haul, kind of roads, price of teams and labor, and the character of 

 the teams should be considered. The cost of loading on the wagons and unloading will depend 

 upon the local conditions, but will ordinarily be from 25 to 50 cts. per ton. For railroad bridges 

 the steel work may ordinarily be brought directly to the site by rail. 



Falsework. If piles are to be used the cost should be carefully estimated. The cost of the 

 piles in place will vary with the cost of piles and local conditions. Under ordinary conditions, 

 piles in falsework will cost from 25 to 50 cts. per lineal foot in place. The cost of the timber will 

 depend upon local conditions and upon what use is made of it after erection. The flooring plank 

 in highway bridges, and ties and guard timbers in railway bridges can often be used in the false- 

 work without serious injury. The cost of erecting the timber in the falsework will ordinarily be 

 from $6.00 to $8.00 per thousand ft. B. M. 



Erection of Tubular Piers. The cost of setting tubular piers for highway bridges will depend 

 upon the conditions. Tubes 36 in. in diameter and 20 ft. long have been set in favorable locations 

 for $25.00 per pair, not including the driving of the piles or the placing of the concrete. It is, 

 however, not safe to estimate the cost of setting tubes from 36 to 48 in. in diameter under even 

 favorable conditions at less than $2.00 per lineal foot of tube. When the cost of setting tubes is 

 estimated by weight, it should be figured at from $15.00 to $20.00 per ton, for ordinary conditions. 

 It will commonly cost from 25 to 50 cts. per lineal ft. to drive piles in tubes, in addition to the cost 

 of the piles, which will vary from 10 to 20 cts. per lineal foot. The concrete will commonly cost 

 from $6.00 to $8.00 per cu. yd. in place in the tube. 



Placing and Bolting. The cost of placing and bolting up riveted highway spans, and erecting 

 pin-connected highway spans, no rivets being driven, is about as follows: 



Highway spans from 30 to 60 ft $12.00 to $15.00 per ton. 



" 60 to 100 ft. . 10.00 to 12.00 " " 



" loo to 150 ft 9.00 to 10.00 " " 



" isoft. and up 8.00 " " 



The cost of placing and bolting up railroad spans will depend so much upon the local con- 

 ditions and equipment that it is difficult to give general costs. 



The cost of driving field rivets in pin-connected spans will vary from 7 to 12 cts. per rivet, 

 while the cost of driving field rivets in riveted trusses will vary from 6 to 10 cts. per rivet. The 

 number of rivets in riveted low truss highway bridges depends upon the number of panels and 

 the style of details, and will be about 155 to 200 for a three-panel bridge, and 400 to 500 for a 

 six-panel bridge. The number of rivets in through riveted highway bridges will be about 250 to 

 300 for a four-panel bridge, and 1,300 to 1,500 for a nine-panel bridge. Pin-connected bridges 

 ordinarily have about $ to J as many field rivets as a riveted bridge of similar dimensions. 



The approximate number of field rivets in single track railway bridges, designed for E 55 

 loading, are given in Table VII. 



* Engineering and Contracting, Aug. 6, 1913. 



