NEW DELHI: National Highways Authority of India ( NHAI ) will convert about 15,000 km of roads from two-lanes to four-lanes for enhancing the economic efficiency of the highways."We are looking at economically efficient corridors and have identified around 15,000 km of roads, which we will convert from two-lanes to four-lanes, to increase their economic efficiencies by connecting points that have been left out historically," NHAI Chairman Raghav Chandra said at a road conference organised by Assocham.Besides, he said NHAI will work with states and ministries to identify the problems at various check posts where multiple agencies connect tolls, state excise tolls and forest tolls so that they can be rationalised.Maintenance got low priority due to poor capital budgeting, Chandra said in the past.The developers being incentivised not just build a road but also maintain it for the life cycle of the concession of the contract, he added."We should have 4-lanes access controlled highways which will ensure the quality of the safety feature," the NHAI Chairman said.Mumbai to Kolkata corridor can be made more efficient by creating a new connection of about 665 km as the road transcends from 4 lane to 2 lane in several places. This needs to be rationalised, which will aid the traffic to move more efficiently and faster, he added.NHAI is also identifying choke points in cities, places which require bypasses, flyovers, interchanges, he said.Chandra said NHAI has identified 184 flyovers to be made in the next 4-5 years, about 294 under passes, 5,000 km of left over service roads, 2 lakh signages and 550 junction points, adding that industry should assist the government in these areas."We will be planting 1,000 trees per km and are looking to plant 10 crore trees over the next 7-10 years. Lot of public sector organisations like Power Finance Corporation and Coal India are coming forward as part of their CSR to tie up with us," he added.