Major disruption to c2c trains this July-August

Due to works on the London Overground extension to Barking Riverside, services on the c2c railway lines in the area are going to be hit with several weeks of serious disruption.
Work starts on Saturday 20 July and finishes on Sunday 4 August.
The engineering work will close the London-bound track between Purfleet and Barking.
In order to keep trains into London running, the services will be diverted via Ockendon, which in turn means that that line will be one-way only, towards London.
However, t