HIGHWAY CONSTRUCTION 19 



necessary for the fulfillment of these conditions. According to the 

 first method, a level or uniformly inclined road might be made from 

 one to the other; this line would cross all the valleys and streams 

 which run down to the main river, thus necessitating deep cuttings, 

 heavy embankments, and numerous bridges; or these expensive 

 works might be avoided by following the sinuosities of the valley. 

 When the sides of the main valley are pierced by numerous .ravines 

 with projecting spurs and ridges intervening, instead of following the 

 sinuosities, it will be found better to make a nearly straight line 

 cutting through the projecting points in such a way that the material 

 excavated should be just sufficient to fill the hollows. 



Of all these, the best is the straight or uniformly inclined, or 

 level road, although at the same time it is the most expensive. If 

 the importance of the traffic passing between the places is not suffi- 

 cient to warrant so great an outlay/it will become a matter of consider- 

 ation whether the course of the road should be kept straight, its surface 

 being made to undulate with the natural face of the country; or 

 whether, a level or equally inclined line being adopted, the course 

 of the road should be made to deviate from the direct line, and follow 

 the winding course which such a condition is supposed to necessitate. 



In the second case, that of two places situated on opposite sides 

 of the same valley, there is, in like manner, the choice of a perfectly 

 straight line to connect them, which would probably require a big 

 embankment if the road was kept level, or steep inclines if it followed 

 the surface of the country; or by winding the road, it may be carried 

 across the valley at a higher point, where, if the level road be taken, 

 the embankment would not be so high, or, if kept on the surface, 

 the inclination would be reduced. 



In the third case, there is, in like manner, the alternative of 

 carrying the road across the intervening ridge in a perfectly straight 

 line, or of deviating it to the right and left, and crossing the ridge 

 at a point where the elevation is less. 



The proper determination of the question which of these courses 

 is the best under certain circumstances involves a consideration of 

 the comparative advantages and disadvantages of inclines and 

 curves. What additional increase in the length of a road would be 

 equivalent to a given inclined plane upon it; or conversely, what 



