DUST PREVENTION AND ROAD PRESERVATION, 1916. Qi 
TaBLE 31.—Contracior’s cost of surface treating Mount Vernon experimental road, by 
experiments. 
Experiment No. 1. Experiment No. 2. Experiment No. 3. 
Item. Cost Cost Cost 
: per : per A per 
Quantity. | Cost. square Quantity. | Cost. square Quantity. | Cost. square 
yard. yard. yard. 
Cents. Cents. Cents. 
General oex- |........---.--- $28.00) 0.669]........-.---.- $39.20} 0.359).-...--........ $90.40} 2.159 
penses. 
Sweepingroad| 4,187 zy uauate 7.00 - 167} 10,915 square | 18.00) . 165} 4,187 square } 20.00 - 478 
yar yards. yards. 
DitbeLing 2,048 gallons. .} 52.80} 1.261) 5,766 gallons- ./108. 00 - 989] 3,557 gallons. ./128.80} 3.076 
oil or tar. 
Isien intra Ovi 2 | eoecoeedoeesee|-eead Moesceee 5,766 gallons.-| 88.00}  .806].-.----.-------]------]...-.... 
Spreading | 54cubic yards] 14.00 .334| 139 cubic | 65.20 . 598] 78 cubic yards} 34.00 - 812 
gravel. yards. 
1,482 gallons, 125.97] 3.009 
. 2,048 gallons 5,766 gallons at 84 cents. 
ULC Scare at Se conte y(i74-08| 4.157 Tt eee y(A61. 28) 4.2261 075 gallons, 176.38] 4.212 
at 84 cents 
Gravel.....-.. 54 cubic yards} 71.23} 1.701) 139 ene 183.37] . 1.680| 78 cubic yards}102.90| 2.457 
yards. | 
ANCE) ole secoecseeeeee 347.11); 8. 289)....---.------- 963.05} 8.823).-..--...--..-- 678. 45) 16. 203 
SUMMARY OF EXPERIMENTS ON GUM SPRING-MOUNT VERNON ROAD, FAIRFAX 
COUNTY, VA. 
The following report describes the condition of the above experi- 
ments when inspected on January 11, 1917: 
EXPERIMENT No. 1.—Coau-TarR PREPARATION. 
The surface is breaking rapidly and becoming mealy, particularly 
up the grade at the beginning of the experiment. There is no well- 
formed mat; deterioration during the 10 days preceding inspection 
was noticeably rapid. 
EXPERIMENT No. 2.—ReEsipuaL ASPHALTIC PETROLEUM. 
The surface has a very uniform mat for short distances, alternating 
with areas which have become badly rutted. Therutting has occurred 
both in cut and in fill, and in at least two places the red clay subgrade 
has worked through the gravel. 
EXPERIMENT No. 3.—Coau-TaR PREPARATION AND Coat Tar REFINED. 
This experiment shows a fairly intact surface, with a rather well- 
formed mat. It has only two or three small areas with any ruts 
whatever, and is not badly rutted anywhere. 
EXPERIMENTS WITH PIPE CULVERTS OF CORRUGATED METAL ON THE 
TEXAS POST ROAD IN COMAL AND HAYS COUNTIES, TEX. 
GALVANIZED AND UNGALVANIZED PIPE MADE OF VARIOUS KINDS OF IRON AND STEEL. 
These experiments are for the purpose of comparing the behavior - 
of different kinds of iron and steel when used in corrugated pipe cul- 
verts under the conditions prevailing in Comal and Hays Counties, 
Tex. All of the culverts were placed in the spring and summer of 1915 
and were in perfect condition when placed. They are reported on 
at this time in order to describe their condition when inspected in 
March, 1917. 
