Four express trains, including two Madurai-bound Vande Bharat Express trains were delayed, for up to one hour after the intermediate block signal (IBS) failed at Samudram between Kolathur and Manaparai railway stations on Thursday night.

According to railway sources, the locopilot of Train No. 22101 Mumbai Lokmanya Tilak-Madurai weekly superfast express noticed that the IBS had failed.