About 21 years after its foundation stone was laid, the Bogibeel bridge, India’s longest railroad bridge, will be thrown open to traffic by Prime Minister Narendra Modi on Tuesday. The 4.94 km bridge, built at a cost of Rs 5,900 crore by the Indian Railways, will reduce travel time from Assam to Arunachal Pradesh to four hours and will also cut down train travel between Delhi to Dibrugarh by three hours.