The vast majority of services connect to or from the Great Eastern Main Line and its London terminus at Liverpool Street.

In the 1960s, the electric supply was converted to 6.25 kV, 50 Hz AC, as part of the decision by the British Transport Commission to adopt 25 kV 50 Hz AC electrification as the standard system, rather than 1500 V DC.

The line was not immediately converted to 25 kV AC due to problems with clearances under bridges.

In 1979, the supply was converted to 25 kV AC, following more research into the permissible clearances between the overhead wires and other structures.

[1] The line is signalled for bidirectional working; there are crossovers at Mountnessing junction, Billericay, Wickford and Hockley.