Infrastructure
The line is owned and maintained by Network Rail. It is part of the Network Rail Strategic Route 7, is composed of SRS's 07.01, 07.02 and 07.03, and is classified as a primary line. The line has a loading gauge of W10 between Liverpool Street and Haughley junction and from there is W9 to Norwich. It has a line speed of between 80-100 mph.
The main line is electrified at 25 kV AC using overhead wires and comes under the control of Romford Electrical Control Room. The branches to Upminster, Southend Victoria, Southminster, Braintree, Clacton-on-Sea, Walton-on-the-Naze and Harwich Town are also electrified.
In between Romford and Chadwell Heath there is a small Network Rail OLE depot adjacent to the Jutsums Lane overbridge. In addition at the London end of the depot is Network Rail's Electrical Control Room that controls the supply and switching of the OHL system for the whole of the former Anglia Region.
Signalling is controlled by two main signalling centres, Liverpool Street IECC (opened in 1992) and Colchester PSB (opened in December 1983). Liverpool Street IECC controls signalling up to Marks Tey, where it fringes with Colchester PSB, which has control to Norwich. There are also several small signal boxes that control local infrastructure, such as Ingatestone box, which has jurisdiction over several local level crossings.
Read more about this topic: Great Eastern Main Line