EARTH, SAND-CLAY, AND GEAVEL EOADS. 



27 



haul. In general, where the material consists of earth it is loosened 

 with plows and the economical method of hauling is fixed by the 

 haul length about as follows: 



For lengths of haul not exceeding 150 feet, drag scrapers; for 

 lengths of haul between 150 feet and 600 feet, wheeled scrapers; 

 for lengths of haul above 600 feet, wagons. Where the material con- 

 sists of solid rock it must be loosened by drilling and blasting and 

 practically always is hauled in wagons or carts, regardless of the 

 haul length. 



The two types of plows commonly used in road grading are shown 

 in Plate III, figures 1 and 2. The former is the type generally used 

 for loosening ordinary soils, while the latter is used for breaking up 

 hardpan, old road 

 surfaces and other 

 earth unusually diffi- 

 cult to loosen. Either 

 type is drawn by 

 four horses, or in 

 some cases by a trac- 

 tion engine, and is 

 operated by three 

 men, including the 

 driver. Plows of the 

 type shown in figure 

 1 of Plate III aver- 

 age about 150 pounds 

 in weight and sell at 

 an average price of 

 from $12 to $18, but 

 heavier plows of this type range in cost up to about $30. With aver- 

 age soil conditions they may be made to turn a furrow about 7 or 8 

 inches deep and from 8 to 10 inches wide. The hardpan plows of the 

 type illustrated in figure 2 of Plate III vary considerably in weight 

 and selling price but cost more than the turn plows. One reason for 

 the higher cost is that the points must be made of a very high grade 

 of steel in order to be durable. 



A drag scraper of the common type is illustrated in figure 16. 

 Such scrapers are made in 1-horse, H-horse, and 2-horse sizes, which 

 have respective rated capacities of 3, 5, and 7 cubic feet. Drag 

 scrapers have an average weight, when empty, of from 75 to 100 

 pounds, and an actual capacity of about three-fourths the rated 

 capacity. The price, f. o. b. factory, averages about from $4 to $6 

 per scraper. 



In operating drag scrapers the drivers also may load and empty 

 the scraper, but frequently it is economical to provide additional 



Pig. 16. — Drag scrapers at work. 



