Stopping the transportation of sand via road, however, remains a challenge, officials said.The issue of sand mining in Bihar recently came into focus when a tractor transporting sand mowed down a police sub-inspector during a raid in Jamui district on Tuesday morning.Bhojpur in particular has been under the scanner of the police and the National Green Tribunal (NGT), which has banned sand mining in Bihar for a certain period of time every year since 2017.In May this year, Bihar Chief Secretary Amir Subhani and DGP R S Bhatti had inspected sites along the Sone river to select a spot for a police picket. The aim was to prevent the plying of sand-laden trucks from Bhojpur and Patna to Saran via the Bhojpur-Chhapra bridge.Authorities then identified that “most cases of sand mining were done through boats”, Bhojpur District Magistrate Raj Kumar said, adding that they then came up with the idea of putting up the pillars. “Miners have been found using excavating machines to load sand into boats. A boat can carry three-four truckloads of sand,” he said.The pillars were made using iron pipes filled with concrete, he said. “We have put these pillars in a zig-zag manner so that even a small boat can’t cross to another side. Our challenge and task is now to stop sand mining via vehicles from the Sahar area,” he said.