NEW DELHI: Now, a mathematical formula will be used to optimise the productivity of passenger trains by determining the number of locomotives required for each train, the railways said today.The railways has a fleet of about 3,300 electric and diesel locomotive passenger trains across the country. Locomotives are deployed to run passenger trains through cyclic schedules called locomotive links.Hitherto, locomotive links were being manually prepared by the respective sixteen zones to operate the allocated trains. Ministry of Railways , with the help of experts, has evolved and implemented the software based decision support system to optimise the deployment of locomotives to run passenger trains at an all India level," the ministry said in a statement."The decision support system utilises a mathematical model to work out the minimum number of locomotives required to run all the passenger trains as per time table while meeting the maintenance and operations requirements," it said.A pilot optimisation exercise was conducted by the Transformation Cell of Railway Board, with active participation of all the zonal railways.This resulted in re-organising of locomotive links, which would free up 30 diesel and 42 electric locomotives (costing about Rs 720 crores) being currently run in passenger services.These 72 locomotives released from passenger operations would be utilised to run additional freight trains and earn additional revenues, it said.The timetabling of passenger trains is a dynamic process in view of periodic changes in train schedules, introduction of new trains and also the change in traction due to ongoing electrification.So, the railways ministry in budget 2018-19 sanctioned a project to be implemented by Centre for Railway Information Systems (CRIS) to institutionalise this process of locomotive link optimisation using decision support system software.