In cases where the traffic will warrant the expenditure, it will be found an advantage to construct a light roof or verandah over a portion of the platforms of roadside stations. This covering will provide a convenient shelter for the passengers and their luggage, and prevent the crowding of booking-halls and doorways during inclement weather. In hot countries a verandah or awning of some description on the platforms is an absolute necessity, and those travellers who have 264 had any experience of railways under a tropical sun, will call to mind the celerity with which the passengers seek such welcome shade. A very important item in the construction of a large terminal station is the roof over the lines and platforms. Wrought-iron and steel can now be obtained in so many convenient sections, and at such moderate prices, that timber-framed roofs, except for very small spans, are now rarely used for railway work. The metallic structure is much lighter in appearance and more durable, besides being less exposed to destruction by fire. The introduction of iron and steel has enabled roofs to be constructed of very much larger spans than would have been prudent to have attempted in timber; at the same time it must be kept in mind that, notwithstanding this increased facility of construction, the cost of a roof per relative area covered increases very rapidly as the span increases. The extent of space to be roofed over in some of our modern terminal stations is so large that the question of roof-spans to be adopted has to be considered very carefully. It has been argued by some that if the area be divided out into small or moderate spans, the presence of the rows of columns for supporting the roof might preclude the possibility of any future re-location of the lines and platforms except by an entire rearrangement of the roof-work. On the other hand, it may also be stated that railway engineers have now obtained such a thorough experience of the necessary relative proportions of platforms and carriage-lines for large stations, as to enable them to lay out these works without any risk of requiring alterations for many years. [Illustration: Fig. 387, 388, 389, 390, 391, 392, 393] [Illustration: Fig. 394, 395, 396, 397, 398] [Illustration: Fig. 399, 400, 401, 402] [Illustration: Fig. 403, 404, 405] [Illustration: Fig. 406] [Illustration: Fig. 407, 408, 409, 410]