RAILWAY CONSTRUCTION. 273 



disadvantage that the steam and smoke from passing trains 

 remained for some time under the roof before it was thoroughly 

 dispersed. The more modern and more economical plan is to 

 put the roof or shelter over the platforms only, and allow the 

 steam and smoke to pass away into the air. In designing the 

 latter class of roof, the fewer supporting columns the better, so as 

 to diminish as far as possible the obstructions on the platforms. 

 Where the platform is unavoidably narrow, the roof may be 

 carried on curved brackets projecting out from the walls. 



Except in tropical countries, where shade is more acceptable 

 than strong light, a liberal amount of glass should be provided in 

 these platform roofs. On many of our home railways they are 

 entirely covered with glass, and the abundance of light is found 

 to be of great assistance in the working of the traffic. Figs. 411 

 to 420 are sketches of a few out of the many types of small roofs 

 which have been erected over single and island platforms. 



Goods-sheds. The form and dimensions of a goods-shed for 

 any station must be determined by the description and amount 

 of traffic to be transacted at the particular place. With an 

 estimate of the traffic before him, the engineer must consider the 

 internal arrangement of building most suitable for the bulk of the 

 merchandise to be accommodated. The principal object of the shed 

 is to permit of goods being transferred under cover from or to 

 railway trucks or carts without being exposed to the weather, and 

 the transfer will be expedited if the arrangements are made the 

 most convenient for the particular class of merchandise presented. 



For some commodities it is considered preferable to unload 

 direct from the railway trucks into carts, or vice versa, and thus 

 have only one handling of the goods. To comply with this 

 method, the cartway must be made almost down to the same 

 level as the rails, to allow the carts or drays to be drawn close 

 up alongside the railway trucks, as shown in Figs. 427 and 428. 

 This type of shed implies a constant supply of carts, so as not to 

 detain the railway trucks, or necessitate the stacking or storino- 

 of goods on the low level floor in the way of carting movements. 



For general merchandise in boxes or bales, a raised loading- 

 bank inside the shed is usually found to be the most convenient 

 arrangement both for loading and unloading. The top of the 

 loading-bank should be a little below the level of the railway - 

 truck floor to give clearance to all truck-doors opening outwards. 

 By means of short portable gangways or landings, the moderate- 



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