DUST PKEVENTION AND ROAD PRESERVATION. 29 
Table 31. — Materials and cost data for experiments at Miami, Fla. 
Quantities of 
Description. 
materials (per 
Cost per square yard. 
square yard). 
6 
ft 
o 
d 
,■ 
d 
d 
d 
W 
£ 
e3 
w 
.2 
d 
<d 
d 
d 
1 
Material and method. 
U 
1 
o 
o 
d' 
c3 
ft 
§1 
-d • 
d Sj> 
C3.g 
bold 
ft 
1 
in 
o 
o 
ft 
c3 
eo 
1 
_g 
1 
ft 
S-l 
1 
£ 
ft 
ft 
3 
o 
d 
3 
o 
H 
O 
A 
< 
fc 
s 
w 
ft 
£ 
m 
a> 
«j 
rt 
o 
Eh 
Sq. 
Cu. 
GaZ- 
Cu. 
Feet. 
yds. 
yds. 
lons. 
yds. 
CTs. 
CTs. 
CTs. 
CTs. 
Cts. 
CTs. 
CTs. 
CTs. 
1 
Light asphaltic pe- 
troleum (semi- 
penetration). 
Light asphaltic pe- 
Cold.. 
96 
213 
0.92 
0.012 
2.34 
14.90 
1.33 
2.23 
1.01 
0.98 
22.79 
2 
...do... 
453 
1,006 
.41 
.012 
2.34 
6.66 
1.33' 1.01 
1.01 
.98 
13.33 
troleum (surface 
treatment). 
3 
Heavy asphaltic pe- 
Hot... 
199 
443 
0.069 
.625 
.012 
2.34 
11.01 
11.37 
1.33 1.52 
1.01 
.98 
29.56 
troleum (pene- 
tration method). 
4 
Light asphaltic pe- 
troleum (pene- 
tration method). 
Cold.. 
168 
371 
.069 
.705 
.012 
2.34 
11.01 
11.42 
1.33 
1.71 
1.01 
.98 
29.80 
5 
Heavy asphaltic pe- 
troleum (pene- 
tration method). 
Hot... 
239 
531 
.041 
.62 
.012 
2.34 
6.61 
11.28 
1.33 
1.51 
1.01 
.98 
25.06 
6 
do 
...do... 
107 
240 
.087 
.99 
.012 
2.34 
16.67 
18.02 
1.33 
2.42 
1.01 
.98 
42.77 
SUPPLEMENTARY REPORT OF EXPERIMENTS MADE AT WASHINGTON, 
D. C, 1912. 
TAR PREPARATION AND OILS— SURFACE TREATMENT. 
The original report of these experiments is to be found in Circular 
No. 99, and the following covers the repairs to date, and the condi- 
tion of the various sections in January, 1914. 
Section No. 1. — Refined water-gas tar preparation. 
This section presents a smooth, hard, mosaic surface and has not 
required any repairs. In a few places along the sides of the road 
the treatment has cracked off for a few inches back from the edge, 
exposing the underlying macadam. 
Section No. 2. — Asphaltic petroleum. 
This treatment showed some tendency to push into slight waves 
and a few small humps, particularly along the south edge of the 
roadway. Several worn depressions in the middle of the road also 
developed during the winter, and apparently had their initial cause 
in the fact that small dust patches had been overlooked in cleaning 
the surface, and the treatment had not adhered properly. At the 
east end of the section, a number of steam pipes pass under the road, 
and the heat from these gives rise to conditions under which it has 
always been difficult to maintain a satisfactory road surface. Three 
distinct displacements of the surface have taken place at this point, 
