BULLETIN 407, U. S. DEPABTMENT OF AGRICULTURE. 

 Table 2. — Corrugated metal culverts. 



Material. 



Coppered 



iron, 



station 



-2+00 



Ingot 

 iron, 

 station 

 9+19 



Coppered 



iron, 



station 



9+43 



Coppered 

 steel, 

 station 

 29+00 



Open- 

 hearth 

 steel, 

 station 

 74+87 



Coppered 

 steel, 

 station 

 77+99 



Ingot 



iron, 



station 



80+94 



Open- 

 hearth 



steel, 

 station 

 218+96 



Diameter inches. . 



Analysis of metal: 



Carbon. ..per cent.. 

 Sulphur . .per cent . . 

 Phosphorus, per 



cent 



Manganese, per cent 

 Copper... per cent.. 



24 



0.03 

 .028 



.0094 



.02 



.16 



15 



0.03 

 .030 



.009 

 .015 

 .05 



0.03 

 .039 



.011 

 .016 

 .16 



0.08 

 .046 



.030 



.37 

 .16 



0.06 

 .026 



.025 



.32 



.016 



0.09 

 .053 



.0105 



.38 



.19 



18 



0.03 

 .038 



.012 

 .009 

 .06 



18 

 0.05 



.027 



.31 



.016 



Concrete head walls were built for all pipe culverts and a concrete 

 gutter was constructed on tlie right from station 29 + 00 to station 

 36 + 18 on a 4.92 per cent grade. 



Four Mile Run Bridge. — It was necessary to build a new bridge 

 over Four Mile Run at station 101 + 87. The design adopted for 

 this bridge was of two 16-foot spans with 16-inch slabs. Work was 

 commenced on the bridge March 6 and was finished June 6. The 

 total cost was $3,332.56. Fifty-eight yellow pine piles were driven 

 to a 20-ton theoretical bearing for the two abutments and the center 

 pier foundations, which were built of concrete mixed in the propor- 

 tions 1 : 2J : 5, The foundations were begun 3 feet 4 inches below 

 low water. No sheeting was used in the excavation for founda- 

 tions and the pits were kept dry by the use of pumps. All concrete 

 was mixed by hand on two large mixing platforms and a washed- 

 gravel aggregate was used. Concrete for the slabs was of 1:2:4 

 mixture, and was reinforced with deformed bars. A railing was con- 

 structed of concrete with a mix of 1 part cement to 2| parts of sharp 

 sand. 



All forms were constructed of dressed lumber and thoroughly 

 braced. The forms for the bridge rail were oiled and other forms 

 were kept wet during the placing of concrete. The rail was given 

 three coats of a wash made as follows: 1 poimd concentrated lye, 4 

 pounds alum, and 5 gallons of water, to which sufiicient cement was 

 added to make a wash that would spread with a large brush. The 

 finished bridge has a clear width of 22 feet. 



Foundation or lase course. — On Section I an average interval of 60 

 days elapsed between the completion of excavation or rough grading 

 and the commencement of subgrade construction and placing of 

 gravel base. The subgrade was prepared exclusively by the use of 

 picks and shovels, and the work was kept from three to five stations 

 ahead of the gravel-base construction. All yielding and spongy areas 

 were removed as rolling progressed and fresh material was supplied. 



The gravel base, on this section, had an average compacted thick- 

 ness of 6 inches, and was constructed of a sand-clay gravel, which 



