The government has pledged £20 million to help Southern rail "get to grips" with its poor performance.
It has announced a series of measures including the appointment of a new "project board".
The move comes after months of disruption to services on the network because of a dispute over the role of guards and staff shortages.
Former Virgin Rail chief operating officer Chris Gibb will head the new project board.
He will work with the train operator, the Department of Transport and Network Rail, to achieve a "rapid" improvement in services.
I want the Southern network to be run by a team of people who work together to make sure passengers get decent journeys and that problems are dealt with quickly. This review will suggest how we achieve a joined-up approach to running the train and tracks and make things work better for the public.
On Tuesday, the company said it would reinstate over 100 services from a total of 300 that were cut from the timetable in July.
This stinks of another multi million-pound taxpayer subsidy to bail out the failing Southern rail part of the Govia Thameslink franchise.