A 48-year-old police constable was killed on Tuesday night after a portion of a piling rig machine being used for a flyover project collapsed on him on the Sion-Panvel Highway in Mankhurd, raising fresh concerns over safety lapses at under construction public infrastructure sites in the city The deceased, Santosh Gopal Chavan, was returning home to Nerul on his motorcycle after completing his duty at the office of the Additional Commissioner of Police (East Region) in Chembur. The incident took place around 9.45 pm on Tuesday near the Tata Power House, in the Vashi-bound lane, shortly after he crossed the Mankhurd T-junction. According to police, a piling rig a heavy-duty machine used to drill deep foundations had been stationed at the site for ongoing flyover work. Investigators said the machine had been placed on uneven ground and was not secured properly. It toppled sideways, and a portion of it fell onto Chavan. He was rushed to MGM Hospital in Vashi by bystanders but was declared dead on arrival.…