Guwahati: Construction of the world`s tallest railway bridge from the point of pillar height has begun in Manipur by the Northeast Frontier Railway Construction Organisation.

The proposed bridge near Noney with pillar height up to 141 metres is slated to become the tallest in the world from the point of pillar height surpassing the existing tallest of Mala-Rijeka viaduct on Belgrade-Bar railway line in Europe where the height of pillars is 139 metre, said an N-F Railway spokesman.

The bridge in Manipur is part of the 111 km-long Jiribam-Tupul-Imphal railway line to connect the capital of Manipur with the broad gauge network of the country, the spokesman said.

The alignment of the railway line passes through steep rolling hills of Patkai region, eastern trail of the Himalayas, he said.

While Jiribam, a small town of Manipur near Assam-Manipur border, is situated 37 metres above mean sea level (MSL), Imphal is situated at 780 metres above MSL.

The alignment has to traverse through not only a number of deep gorges but over several rivers flowing at low ground levels necessitating construction of 46 tunnels measuring a total 54.5 km in length and tall bridges to maintain a suitable gradient for efficient operation of railway, he said.

The longest tunnel will be 4.9 km long between Jiribam-Tupul and 10.75 km between Tupul-Imphal section. While the high mountains are penetrated by constructing

tunnels, the deep river gorges between the mountain ridges are connected by tall bridges.

The tallest of such bridges near Noney spans over a gorge with an overall length of about 700 metres, he said, adding, Railway had constituted an expert group to study the possible alternative span arrangements of such tall bridges considering parameters like the length of span, type of span, location of the piers, constructibility, serviceability, geological features, possible tectonic movement.

Based on the recommendations of the expert group, it was decided that main superstructures will be steel open web through type girders of 103.5 metre span (centre to centre of bearings).

The pillars are of reinforced cement concrete (RCC) hollow type with the tallest pillar being 141 metre high, while the height of other piers of this bridge vary from 50 metres to 90 metres.

The first phase of the project from Jiribam to Tupul (84 km), which includes this bridge, is slated for completion by March 2016, the spokesman said.

An arch-type railway bridge under construction on Chenab river in Jammu-Kashmir line bridging a gorge of about 360 metre depth from bed of river to the rail level is being considered as the highest railway bridge in the world, he informed.