Watch: 9 trains a day, 3,800 tonnes coal in each - what the toxic train leaves in Goa

Every two hours on average, a freight train pulls out of Mormugao Port, 6 km from Vasco. Each of its 58 wagons is covered with blue tarpaulin, the edges of which flap in the breeze, revealing what lies underneath — about 65,000 kg of coal, the toxic black dust hanging in the air like a shroud over each wagon. The Indian Express tracked over a dozen such trains up to the Goa border — except for a 5-km stretch where access was denied during the monsoon because of the presence of a waterfall. And found that each train gouges out a thick black line (see map below) starting from the port at the western tip, dipping south around Velsao, snaking up from Sanvordem, crossing the Zuari river network, villages around Chandor, paddy fields, indigenous habitats in Majorda, cashew and coconut orchards, and fragile forests before reaching Kulem just short of the Western Ghats.