NEW DELHI: A driverless Delhi Metro train, running on the Magenta line, on Tuesday rammed into a wall at Kalindi Kunj depot when it rolled back on a ramp when being taken for washing."The person who took charge of the train from the maintenance staff also did not check brake and proceeded with the train up to the washing plant built on a ramp. While stopping at the ramp, since the brakes were not available, the train rolled back causing this incident," ANI quoted DMRC as saying.According to the norms, when a train enters a workshop or depot, its brakes are decommissioned, to ensure thorough and detailed check, reported PTI.Once the train is re-commissioned, the brakes are tested by the maintenance staff in the depot before the train leaves the shed. The train movement inside the workshop area is done manually and not by the signalling system.There were no passengers on board when the accident occurred.DMRC termed the incident "prima facie a case of human error and negligence," and ordered a high-level inquiry by a three-member committee.It promised "appropriate action" after the inquiry. The Delhi government has also sought a report from the DMRC.The 12.64 kilometre-long Magenta line, expected to be inaugurated by Prime Minister Narendra Modi on December 25, runs from Delhi's Kalkaji Mandir station to Noida's Botanical Garden.Trains on the Magenta line will be the first to be driverless in the history of the Delhi Metro. However, drivers will be present on the trains for some time.The new line will make it easier and faster for Noida residents to travel to south Delhi. The train will travel through nine stations - Kalkaji Mandir, Okhla NSIC, Sukhdev Vihar, Jamia Milia Islamia, Jasola Vihar, Shaheen Bagh, Kalindi Kunj, Okhla Bird Sanctuary and Botanical Garden.