Lower Sone Bridge
It appears that this is the bridge now known as the Koilwar Bridge (officially known as the Abdul Bari Bridge).
From Engineering: 'The main line of the East Indian Railway, from Calcutta to Delhi, crosses the Sone River, a tributary of the Ganges, 20 miles west of Patna, the capital of Behar Province. The double-line track is taken across the river on a bridge of 28 spans, each 162 ft. between centres of piers. The up and down tracks are carried each on their own set of girders, which are placed close together on brick piers founded in the river bed. The original bridge was completed about 1867, the railway track being carried on the top of wrought-iron lattice girders. A timber roadway was provided underneath the railway track to accommodate road traffic. Reconstruction work was commenced in 1925, the old up-track bridge being replaced by mild steel girders carrying the railway track overhead, and a concrete roadway 16 ft. wide beneath. The replacement of the old down-track bridge was undertaken in 1929, and forms the subject of this article. The old bridge was replaced by girders similar to those used for the up-track, but an inspection footpath only was provided underneath, as the roadway on the up track was considered sufficient to meet the limited requirements of road traffic. .... The general scheme of replacement was to use the old girders as falsework for erecting the new girders, when the new girders were riveted up and self-supporting,4o suspend the old girders to the new, then cut them up and remove them. Alterations to the pier heads %ere necessary, and new masonry bearings had to be built for the new girders. Also before using the old girders as falsework, they had to be manoeuvred into suitable position, which involved slewing them 5 ft. 1 in. to one side and lowering them bodily 5 ft. During regirdering, the down-track was closed to traffic, single line working on the up-track being enforced. .... Messrs. Sham Singh and Company, contractors, Calcutta, supplied the labour for this work on a lump sum contract. The contract was entirely for labour, the Railway Administration supplying all material, tools, plant and stores and supervising and directing all work. Railway staff operated cranes, locomotive, workshops and power-house, and were responsible for the supply of water and air, and the maintenance of all tools and plant. ..... The steelwork for the new spans was manufactured in India by Messrs. Kumardhubi, of the Kulti Iron Works, Barakar. The steel used was to British standard specification, and the material was obtained partly from Messrs. Tata’s Rolling Mills at Jamshedpur, India, and the remainder sent out from Great Britain. The girders were manufactured to the design, working drawings and specification of the consulting engineers to the railway, Messrs. Rendel, Palmer and Tritton, Westminster. All material was drilled to steel-bushed templates,similar members of the 28 spans being interchangeable. As a check on manufacture, one span in every ten manufactured was erected in the maker’s yard, the members used for this span to be erected, being chosen at random from the finished material. The steelwork went together at site admirably, ..... The new girders were designed to take Indian State Railway H.M. Loading, ..... The erection scheme was worked out and the project carried to completion by Mr. Henry S. Kerr, to whom we are indebted for the above particulars, Mr. Kerr having Mr. Ganapati, as assistant engineer.'[1]