Bridging The Mighty Indus PART-II.

When Lord Roberts became C-in-C India in 1885, he advocated that to defend north-west India, troops would have to be concentrated at two points-Peshawar and Quetta. He, therefore, formed two army commands one for each axis-Northern and Southern. Aligning with this strategic policy, the Scinde, Punjab, and Delhi Railways (which were stockbroker companies registered in Britain), were purchased by the Government and amalgamated to form the North Western Railway (NWR). By 1880, a railway line from Karachi along the western bank of the Indus had been constructed till Sukkur and on the far side extended across the waterless desert to Sibi. The first line to Quetta had also been opened in 1886 and there was now a need to link these lines with the Lahore-Rohri Section that had been constructed by the Indus Valley State Railway. At Rohri the Indus flows through a gap in a range of low limestone hills and a steam ferry would transport eight wagons at a time across the river-a process that was slow and unwieldy.

Bridging the Indus at Sukkur had been on the cards since 1872 and for the next ten years, various designs had been considered including a suspension bridge with cables formed of steel links. Bridging the smaller channel of 180 meters between Sukkur and the island of Bukkur was straightforward, since its rocky bottom provided a solid foundation for masonry piers. However, the wide and deep Rohri channel of 260 meters that was filled with silt, posed a problem for constructing piers. In spite of this, in 1882 it had almost been decided to construct a bridge with spans of 75 meters resting on masonry piers, when a severe flood further deepened the channel to 30 meters.

Sir Alexander Rendel, one of the best civil engineers was asked to submit a design without piers. He already had two major railway bridges to his credit: the Alexandra Bridge and the Empress Bridge, but both consisted of spans supported by masonry piers. He proposed a very unusual design of two anchored cantilevers, each 95 meters long, carrying a suspended span of 60 meters in the middle. In spite of an unusual structure, the design was accepted and a contract awarded for the material. Prior to shipping the steelwork, the contractors had assembled the 50 meters tall cantilevers in their yard in UK, much to the amazement of the spectators. With most of the pre-fabrication undertaken back in Britain, the builders on site were often accused of being little more than 'Meccano...