"The cause of the derailment will be known after the inquiry report submitted by the Commissioner Railway Safety Chetan Bakshi. But primarily the reason seems to be the rail weld fracture," sources in railways said here.
If the welding is not done with proper support system then it causes fracture. An ultra sound test detects the rail weld fracture.
Four coaches of the passenger train derailed between Nagothane and Roha stations of Raigad district on Sunday killing 21 passengers and injuring about 130.
It is a matter of serious concern for railways that two trains derailed in that section in quick succession.
"I had spoken with railway officials and they have explained me certain things. Inquiry is going on. I am waiting for the detailed reports. After getting the report we can say what is the cause for this accident and who are responsible and what had actually happened," Railway Minister Mallikarjun Kharge said at Roha station after visiting the accident site.