26 BULLETIN 586, U. S. DEPARTMENT OF AGRICULTURE. 
(4) The work on this experiment: was delayed because of bad 
weather, but the old road surface was uniformly in fairly good condi- 
tion when the work was done. 
Cost data. 
The bid prices were based on furnishing and placing the materials 
by the material unit and were as follows: 
1. Light coal-tar preparation in place, per gallon...........-....- $0.16 
2. Heavier coal-tar preparation in place, per gallon............-- 16 
3. Asphaltic oilinjplace,.per gallon!) ocean bee eee wits: say 
4. Gravel for top-dressing in place, per cubic yard.....-.......-- 1.05 
At the above unit prices the costs per square yard for the different 
experiments were: 
_ Cents. 
For experiment No. 1 (cold tar)..........-.2e.-ecceeeceeeeeeeee 9.18 
For experiment No. 2 (residual asphaltic petroleum)............- 10. 32 
For experiment No. 3 (2 applications of tar—1 cold, 1 hot)..--.. 15. 26 
Total contract price for the three experiments, $2,149.57. 
During the progress of the work, and with the cooperation of the 
contractor, a record was kept of both the labor employed and mate- 
rials used. Tables 30 and 31 show an itemized summary of the costs 
to the contractor, which are based on the following scale of unit costs: 
Horemran per Outen os sens jcelae sssce scree cn ce ces esas ot erem aetna $0. 50 
Laborers;perhourt.2). Ou. SefO 02. ihc ee ok IL Ae 25 
Helper on truck distributor, per hour..........-.....--.--------- . 30 
Driver for truck distributor, per hour.............-..----------- .40 
Auto truck for hauling gravel (including driver and supplies), per 
OU sya cre! Secs Seine Besa cia aySioIe Sie bala elacc a epojoin acopeis clays 00 
TABLE 30.—Cost data for excavating, screening, and hauling gravel for top-dressing. 
j Unit cost, 
Item. Quantity. | Total cost. | per cubic 
yard. 
Cubic yards 
Woosenin pera elec ceccice ccmececesccine se elec oeeleee' lacisincoe cee eee 271 $56. 50 $0. 2085 
Screeningigrayel (vl. False SSI Ee JO SEES Ss sss eS Ee 271 53.50 - 1974 
Loading and dumping gravel............-..-0--0-00-e0e2e-- eee eee 271 46.00 - 1697 
Is ey hots eae hye oo saceodece ioenooKUadondnsdodeaScbodéosse ees 271 184.00 - 6789 
Stripping ple seiserseeeselacleespicieeiscnee aeeceiiceiemscinie ecece eee 271 4.00 - 0147 
Grav ela tee reese see toctsce ee aa ee sence ecco eeiceen ete 271 13.55 05 
Dotalssjcees sek. see ee se ee Eee ae ache nee 271 357.55 1.3192 
1 Average haul for gravel, 3,900 feet. The high cost of hauling is due to the use of an auto truck that 
could be kept running but a small portion of the time. 
