RAILWAY CONSTRUCTION. 233 



it passes either over or under both main lines, and continues on 

 to G without in any way interfering with the train service on 



ABC; 



Fig. 347 is an ordinary plain siding or turn-out, including 

 the necessary throw-off or trap-points and short dead end. 



Fig. 348 is an ordinary cross-over road from DOWN main 

 line to UP main line, and vice versa. 



Fig. 349 is a double cross-over road, generally termed a 

 scissors cross-over. 



Fig. 350 is a simple through cross-over road from DOWN 

 main line to siding alongside UP main line. 



Fig. 351 is a similar arrangement of through cross-over road 

 with the addition of a pair of slip points at S to make a con- 

 nection with the UP main line, thus combining the facilities of 

 the ordinary cross-over and through cross-over road. 



Fig. 352 shows a set of three throw-switches with all the 

 sliding tongues placed side by side ; and Fig. 353 shows another 

 arrangement of three throws with the sliding-rails of the second 

 set of switches placed just behind the heel of the first set of 

 switches. The latter method works very well where there is 

 sufficient length for the purpose. 



Fig. 354 shows a square crossing, where one line of railway 

 crosses another line of railway on the same level. 



Fig. 355 shows a connection with a siding by means of an 

 ordinary carriage or waggon turn-table. 



Fig. 356 shows a set of " runaway " points which are some- 

 times placed in the main line at the top of an incline close to 

 a station, the object being to intercept or throw off any portion 

 of a train which may have become detached, and which would, 

 if unchecked, run away back down the incline. By means 

 of a weighted lever or spring the points are set to the normal 

 position of open to the siding, and as they are " trailing " points 

 for the running road they are readily closed by a passing train. 

 One or other of the above forms of connections, or a combination 

 of them, will meet all the requirements which usually occur in 

 railway work. 



Fig. 357 is an enlarged sketch of an ordinary cross-over road, 

 and Fig. 358 of a double or scissors cross-over. 



Fig. 359 shows a single-slip point connection, and Fig. 360 

 a double-slip point connection. In places where slip connections 

 can be introduced they add greatly to the facilities for train 



