Usually track fractures occur because of temperature fluctuations. A welding failure points towards negligence.
On Monday, commissioner of railway safety (CRS) Chetan Bakshi, who is conducting an inquiry, said he would hold a public hearing on Thursday to record evidence. He will also record the accounts of railway employees.
Read: Maharashtra train derailment kills 21; traffic resumes
Around 9.25am on Sunday, the train had derailed outside Bhise tunnel near Nidi station, between Nagothane and Roha on the Konkan route. Traffic on the route was restored on Monday, 20 hours after the accident.
Satish Bagal, resident deputy collector, Raigad, said as per the updated figures, 22 people have lost their lives and 176 were injured, of whom 50 are being treated at various hospitals.