Suburban services on Central Railway (CR) collapsed during the evening peak hours on Friday after a local train from Kalyan that was entering Thane station possibly violated a signal, blocking the path of another train, which was crossing over from the fast to slow line. 

This caused the route to come to a standstill, as an in-built safety mechanism had kicked in. The mechanism ensures that all trains in a section come to a halt in the case of a breach of signals, and things need to be set right by overriding them manually.