NEW DELHI: The roads ministry has proposed to construct 25 leafy underpasses for animal movement as part of 10 national highways that pass through forests and wildlife sanctuaries in order to ensure environmental clearance for the projects.The measures will add to the cost of construction, but that isn’t a worry since these will reduce the impact on the natural habitat of animals, a senior National Highways Authority of India ( NHAI ) official said.These proposed highways would pass through sanctuaries such as the Madhav National Park near Gwalior; Chambal and the corridors connecting the Kanha and Pench tiger reserves; Rajaji National Park in Uttarakhand and dense forests of Assam. Cost of construction for these nearly 1,900 km of highways is estimated to be about Rs 20,000 crore.The cave-like, concrete underpasses that the Ministry of Road Transport and Highways has proposed will be layered with natural soil so that they resemble the natural habitat of the animals. The underpasses will be fitted with CCTV cameras to monitor the movement of animals.According to a senior ministry official, these structures will be constructed so biodiversity is untouched. Stretches passing through green corridors will have fencing to prevent vehicles from entering the core zone. Speed of vehicles will be restricted to 40 km an hour.The Wildlife Institute of India (WII) and National Tiger Conservation Authority have prepared draft guidelines for mitigation of impact of linear projects in forest ranges. For instance, height of underpasses has been suggested to be a minimum of six metres to help elephants.The government is working with the WII to implement these. “Animals have a set pattern and route of movement according to which special paths underneath the elevated road stretch would be made,” the NHAI official said. State wildlife boards will also be drafted into the projects.