DUST PEEVENTION" AND KOAD PRESERVATION, 1915. 
45 
Table 46. — Cost data, bituminous limestone. 
Item. 
Rough grading 
Subgrade 
Shoulders 
Quarrying, labor 
Quarrying, explosives 
Loading and hauling 
Spreading base course 
Screening limestone for wear- 
ing course 
Spreading wearing course 
Asphaltic oil, 1,801 gallons, 
f . o. b. Baltimore, Md 
Cost per 
Total 
square 
cost. 
yard of 
surface. 
$45. 15 
$0. 0247 
48.82 
.0266 
77.84 
.0424 
86.84 
.0473 
51.31 
.0280 
179. 80 
.0980 
10.00 
.0055 
42.05 
.0230 
8.65 
.0047 
108.06 
.059 
Item. 
Freight on oil 
Hauling oil to road 
Heating and applying oil 
Hauling, screening, and 
spreading sand 
Rolling (including cost of coal) 
Incidentals and supervision. . . 
Total cost 
Total (exclusive of shoulders) . 
Total 
cost. 
$57. 44 
8.80 
24.52 
8.80 
47.56 
52.41 
858. 05 
780. 21 
Cost per 
square 
yard of 
surface. 
$0.0313 
.0048 
.0133 
.0048 
.0258 
.0286 
.4674 
.425 
Table 47. — Cost data, sand-asphalt. 
Item. 
Rough grading 
Subgrade 
Shoulders 
i Asphalt, 21.77 tons, including 
freight 
Hauling asphalt (3£ miles) 
j Screening and heating sand. . . 
Heating asphalt 
\; Mixing sand and asphalt 
i Transporting mixture 
Cost per 
Total 
square 
cost. 
yard of 
surface. 
$34. 80 
$0. 0282 
25.01 
.0203 
119. 60 
.0969 
418. 70 
.3393 
14.77 
.0120 
310.00 
.2512 
67.02 
.0543 
192. 09 
.1557 
70.30 
.0570 
Item. 
Spreading mixture 
Hand rolling 
Power rolling 
Total cost 
Total (exclusive of shoulders) 
Total (exclusive of rough grad- 
ing and shoulders) 
Total 
cost. 
$39. 56 
5.45 
20.75 
1,318.05 
1,198.45 
1,163.65 
Cost per 
square 
yard of 
surface. 
$0. 0320 
.0044 
.0168 
1. 0681 
.9712 
,9430 
SUPPLEMENTARY REPORTS ON EXPERIMENTS PREVIOUSLY 
REPORTED. 
The experiments which were in progress at the beginning of the 
: year have all been described in previous publications of the Office, 
and reference is made to these publications by number, in the descrip- 
tions below. It will be noted that the experiments undertaken at 
New York, N. Y., and Ridgewood, N. J., in 1910; at Boise, Idaho, in 
1910, and at Newton, Mass., in 1908, have all been discontinued. As 
explained in Department Bulletin No. 257, the reasons for dis- 
continuing these experiments were either that they have proved 
failures or that subsequent improvements have destroyed their 
value from the standpoint of furnishing comparable results. 
SUPPLEMENTARY REPORT OF EXPERIMENTS AT LEMON CITY, FLA., 1914. 
OILS, TAR PREPARATION, CALCIUM CHLORIDE-CORALLINE ROCK. 
The original report of the details of construction of these experi- 
mental sections was published in U. S. Department of Agriculture 
Bulletin No. 257. 
In July, 1915, a surface treatment of asphaltic material was ap- 
plied uniformly to all the sections by the county road authorities. The 
