28 BULLETIN 463, U. S. DEPARTMENT OF AGRICULTURE. 



laborers for this purpose. With a haul length of 100 feet and the 

 teams moving steadily, one laborer should be able to load or empty 

 and spread the material for about three scrapers. For scraper work 

 to be effective the material to be excavated must be thoroughly 

 loosened by the plows and should be free from large roots or stones. 

 Where such obstructions occur time is saved by having them removed 

 by hand during the progress of the plowing. 



The average small organization for carrying on road-grading 

 work with drag scrapers is made up about as follows : 



5 cubic 



Force : 



Tools : 



1 foreman. 



6 drag scrapers (capacity 



4 to 6 scraper drivers. 



feet). 



2 laborers for loading scrapers. 



1 road plow. 



2 laborers for dumping and 



2 picks. 



spreading. 



2 axes. 



1 driver for plow. 



2 mattocks. 



1 laborer to hold plow. 



3 shovels. 



1 laborer for trimming shoulders. 





etc. 





4 1 to 6 two-horse teams for 





scrapers. 





1 or 2 two-horse teams for plow. 





Total, 1 foreman, 14 laborers, and 





7 teams. 





The force emploj^ed should vary somewhat with the haul length, 

 which is usually between 25 feet and 150 feet. Under average con- 

 ditions an organization such as that described above should move 

 from 300 to 350 cubic yards of earth per 10-hour day. 



An objectionable feature of drag-scraper work is that the embank- 

 ments tend to settle very irregularly. The reason is that the succes- 

 sive loads are not spread out uniformly as they are dumped, but 

 are deposited as a succession of rather compact cores with the 

 intervening spaces consisting of comparatively loose material. The 

 loose material settles more than the compacted spots, and this un- 

 equal settlement produces pockets in the surface which hold water 

 and gradually become deepened under the action of traffic. Where 

 the material to be moved is loose and light, such as the prairie soils 

 of the Middle West, this objection can be overcome largely by sub- 

 stituting Fresno or Buck scrapers for the common type of drag 

 scrapers. 



Fresno scrapers are made in several different sizes and range in 

 capacity from about 8 to 12 cubic feet. They are drawn usually by 

 three or four horses, and can be operated in almost as small a space 

 as drag scrapers. Their average cost is from $15 to $20 each. One 

 principal advantage of Fresno scrapers is that the runners may be 

 adjusted to spread out the load to any desired depth from 2 or 3 



1 Where necessary, one of the scraper teams may be used to help the plow team. 



