Guwahati: The Brahmaputra Express Highway along the 890-km bank of the river from Sadiya in the east to Dhubri in western Assam will be one of the most challenging infrastructure projects in the world, according to a recent concept note prepared by the state government.

The project, which aims to dredge the Brahmaputra for proper navigation and flood control and construct the highway with the dredged material, was approved by the Union ministry of surface transport in April last year.

An estimated Rs 40,000crore is likely to be spent for the project.

The concept note prepared by the water resources department says though the Brahmputra touches almost every district of Assam, there is no such highway along its bank.

"If one such highway is constructed along the river bank, it will not only boost surface transport, but will also facilitate tremendous growth in tourism. The remote areas will be connected by a highway. Construction of such highwaysshould be taken up with the dredged materials," it says.

The state government has recently said dredging of the Barak river is under way and the one for the Brahmaputra will also begin for proper navigation of the vessels to be operated by the Inland Waterways Authority of India and other private players to revamp water transport in the Northeast. The survey for construction of the express highway is under way.

The state government had moved the Centre with a request that nearly 5,000km embankments, which were constructed as short-term relief from floods, need to be converted into road-cum-embankments as most of them are more than 50-year-old without any repairs.

The concept note saysthe existing highway network in Assam is insufficient to cater to the growing traffic load that increased from 9.4 per cent in 2006-07 to nearly 12 per cent in 2014-15.

It says the project, including the expressway, is viable.

"The embankment-cum-expressway crest will be 2.5metre higher than the highest flood level of the Brahmaputra. The riverside will have a variable margin of 50 metres to 100 metres. The marginal area will be at level of the highest flood and outfalls of the tributaries on both banks of the Brahmaputra will be extended amid guide bunds until it crosses the expressway below a bridge," it says. The state government recently said that the Union transport ministry had engaged Water and Power Consultancy Service for preparation of a detailed project report.