Rail passengers in Worcestershire and Gloucestershire should benefit after new signalling equipment is installed.
It will shorten the time it takes for trains to reverse at Worcester Foregate station and so improve time-keeping.
It is part of a Network Rail drive to improve train punctuality along the Cotswold Line.
It means London Paddington trains terminating at Worcester Foregate Street will, for the first time, turn round without leaving the station.
Network Rail engineers have replaced nearly a mile of track on the Cotswold Line north of Moreton-in-Marsh.
This allowed a speed restriction to be lifted, reducing delays for passengers.