CHAPTER II. 



Works of construction : Earthworks, Culverts, Bridges, Foundations, Screw piles, 

 Cylinders, Caissons, Retaining walls, and Tunnels. 



Earthworks. Under this heading may be classified cuttings and 

 embankments of earth, clay, gravel, and rock. 



When setting out a line and adjusting the gradients, an 

 endeavour is usually made to so balance the earthworks that 

 the amount obtained from the cuttings may be sufficient to form 

 the embankments. With care, this may be effected to a consider- 

 able extent ; but there will be places where the material from 

 cutting is unavoidably in excess, and others where the cuttings 

 are too small, or contain good rock, or gravel, which can be 

 more advantageously used for building and ballasting purposes 

 than for ordinary embankment filling. Or there may be a 

 large cutting which will provide enough material to form three 

 or four of the adjoining embankments; but the distance, or 

 lead, as it is termed, to the far embankment may be so long, 

 and, perhaps, on a rising gradient, that it would be cheaper to 

 run the surplus cutting to spoil, and borrow other material 

 for the far embankment from side cutting or elsewhere. A 

 long lead adds materially to the cost and time of forming an 

 embankment, as it not only necessitates a considerable length 

 of service, or temporary permanent way, but also occupies 

 much time in the haulage of the earth waggons. For distances 

 of half a mile and upwards, a small locomotive is more suitable 

 than horses for conveying the waggons. 



To run to spoil is the term applied to such of the material 

 from a cutting which, not being required or utilized in the 

 formation of the line embankments, is removed and tipped into 

 mounds, or spoil-banks, in some one or more convenient sites 

 near the mouth of the cutting. Sometimes the surplus material 

 is disposed of by increasing the width of the embankments. 



