HIGHWAY CONSTRUCTION 



113 



at least to reduce it to a minimum. In some cities, ordinances have 

 been passed, seeking to regulate the sprinkling of the streets; and in 

 many places the gutters are laid with stone or vitrified brick (see Figs. 



Fig. 64. 



64 and 65), while in others the asphalt is laid to the curb, a space of 

 12 to 15 inches along the curb being covered with a thin coating of 

 asphalt cement. 



Asphalt laid adjoining center-bearing street-car rails is quickly 

 broken down and destroyed. This defect is not peculiar to asphalt. 

 All other materials when placed in similar positions are quickly worn. 

 Granite blocks laid along such tracks have been cut into at a rate of 

 more than half an inch a year. The frequent entering and turning off 

 of vehicles from car tracks is one of the severest tests that can be 



Asphalt 



Brick Gutter 



Curb* 



Fig. 65. 



applied to any paving material; moreover, the gauge of trucks and 

 vehicles is frequently greater than that of the rails, so one wheel runs 

 on the rail and the other outside. The number of wheels thus travel- 

 ing in one line must quickly wear a rut in any material adjoining the 

 center-bearing rail. 



To obviate the destruction of asphalt in such situations, it is usual 

 to lay a strip of granite block or brick paving along the rail. This 

 pavement should be of sufficient width to support the wheels of the 

 widest gauge using the street. 



