In order to describe fully the complete conquest which the iron horse has accomplished in British India, volumes would be required. In that country the steel highway has been driven forward in the face of prodigious difficulties of every description; the story is an exciting romance.
But the features which impress the traveller most strongly are the bridges. Some compel more than passing interest because of their great length, such as the Sone bridge, on the East Indian railway, which consists of 93 spans, giving the structure a total length of 10,952 feet, making it one of the longest bridges in the world; or the Godavari over the river of the same name on the Madras North-East line, 9,066 feet in length; others because of their height, as, for instance, the Gokteik Viaduct in Burma, 325 feet high; or the Dhorabhave Viaduct, 178 feet above the stream; while here and there attention is challenged because of the massive proportions of the structure or its unusual design, as, for instance, the Jubilee Bridge across the river Hooghly at Naihati, or the Lansdowne Bridge across the Indus at Sukkur, the main span of which is 790 feet clear.
It may be safe to assert that no country has offered the bridge-builder such striking opportunities to display his ability or enterprise as the Indian Empire. The Americans point to the great width of their waterways, and the huge structures which leap across the Mississippi, Missouri or Columbia rivers, but, compared beside the erections which carry the railway across the Indian waterways, they appear puny.
The Indian rivers are famous for their great width, and the extent to which they break up the country through which they make their tortuous ways to the sea. The result is that when the engineer is called upon to cross from bank to bank, especially in connection with the more important waterways, he is faced with some teasing and complex problems, to solve which demands often considerable ingenuity and the expenditure of much racking cogitation. These rivers are bad friends to the engineer at the best of times, but when lashed into fury and swelled to flood they almost defy mastery.
The flood is the bugbear of the bridge-builder. One never knows what the enraged water is going to do next. Sir Bradford Leslie, K.C.I.E., M.INST.C.E., who probably has been associated with more great engineering achievements of this character in India than any other living engineer, can recall thrilling moments innumerable. For instance, when he was carrying the Jubilee Bridge across the river Hooghly, the water carried away one of the caissons which he was about to launch for one of the piers. He thought it had been lashed safely into position by means of chains, preparatory to sinking, but the Hooghly “bore” quickly undeceived him. The Hooghly bore is an ugly customer, for at times it attains a height of 7 feet, and travels up-stream for 70 miles in four hours. This rapidly-moving bank of liquid struck the unlucky caisson, although the latter was of respectable dimensions and weight, snapped the mooring chains as if they were pack-thread, and carried the cylinder away as if it were a small butter-tub. The engineer had a lively chase up-stream after his work, and finally secured it stranded in an awkward position about half-a-mile above its site.
Immediately arrangements were hurried forward to salvage the caisson. After a day and a half’s continuous hard toil it was recovered and anchored alongside the bank until the next propitious moment arrived for it to be towed out into the stream and sunk into position.
In the early days the engineers in their bridge-building operations suffered the maximum width of a river to dictate what the length of such a structure should be. Seeing that the normal channels of many of these waterways are narrow in comparison with what they attain under flood, this rendered bridge-work exceedingly expensive and intricate. It is no uncommon circumstance for a waterway, when swollen by the rains of the wet season, to spread out for a width of three miles or more. It becomes practically insatiable, the soft earth forming the banks falling a ready victim to the powerful eroding action of the scurrying water. The result is worse than that brought about by the scouring of the River Mississippi, which devours huge masses of land continually on either bank. When the Indian river falls, unsightly stretches of undulating sandbanks are revealed, riven by little back channels and small lagoons, which present a general aspect of desolation. Under such circumstances, bridging from bank to bank is a somewhat vague undertaking, for the simple reason that it is difficult to decide what are the limits of the waterway, because erosion continues until the water reaches material which defies this action.
The engineer has met this situation now in an ingenious manner. He determines the channel of the river and keeps it within bounds by means of an artificial wall or training-bund, which is carried parallel with the navigable channel, the flow of water through the space between the inner side of the wall and the shore being obstructed by a solid embankment which carries the track. This system was employed first by Mr. J. B. Bell to carry the North-Western State railway across the Chenab River at Sher Shah, and proved so eminently successful that it has come into general favour.
THE TRAINING-BUND OR WALL TO NARROW THE GANGES BY 3000 FEET FOR THE CURZON BRIDGE, SHOWING RAILWAY APPROACH