﻿VITRIFIED BRICK AS MATERIAL FOR COUNTRY ROADS. 9 



The shoulders, while essentially a part of the road surface, should 

 be constructed at the same time that the subgradc is formed. This 

 is necessary in order that the curb may be properly supported while 

 the pavement is being laid and rolled. The shoulders should never 

 be less than 4 feet wide and should consist of some material which 

 compacts readily under the roller and which does not readily absorb 

 water. Not infrequently one of the shoulders is made sufficiently 

 wide to form an earth roadway parallel to the brick pavement. 

 Such an arrangement serves to relieve the pavement of considerable 

 traffic during favorable seasons and thereby adds greatly to its life. 

 The general method of constructing shoulders for brick roads is not 

 essentially different from that employed for other types of pave- 

 ments. 



CURBING. 



All brick pavements should be supplied with strong, durable 

 curbing, both on the sides and at the ends. Otherwise, the marginal 

 brick will soon become displaced by the action of traffic, and their 

 displacement will of course expose the brick next adjoining, so that 

 deterioration will soon spread over the entire pavement. Properly 

 constructed curbing, on the other hand, will hold the pavement as 

 in a frame and enable the brick to present their combined resistance 

 to the destructive influences of traffic. 



Satisfactory curbs may be constructed of stone, Portland cement 

 concrete, or vitrified clay shapes made especially for this purpose. 

 Wood has also been used for curbs to a limited extent, but when it is 

 considered that the life of a brick pavement under ordinary condi- 

 tions should far exceed the life of any wood curb which might be 

 devised, the economy of employing a more durable material is 

 readily apparent. 



Stone curbing may be made from any hard tough stone which is 

 sufficiently homogeneous and free from seams to admit being quar- 

 ried into blocks not less than 4 feet long, 5 inches thick, and 18 

 inches deep. On account of their ordinarily homogeneous structure, 

 granite and sandstone are probably more used for curbs than any 

 other kind of stone. 



All stone curbing should be hauled, distributed, and set before 

 the subgrade is completed. The individual blocks should be not 

 less than about 4 feet long except at closures, and should have a 

 depth of from 18 to 36 inches, depending on traffic conditions and 

 on whether the curb is to project above the surface forming one side 

 of the gutter. The neat thickness need never be greater than 6 

 inches and, where the traffic conditions are not severe and the quality 

 of the stone is good, a thickness of 4 inches will ordinarily prove 

 satisfactory. Stone curb should always be set on a firm bed of 

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