Shenfield is on the Great Eastern main line from London Liverpool Street. As well as the express services to Norwich, there are frequent services to Ipswich, Southend Victoria (diverging from the main line here), Braintree, Clacton and Colchester Town, plus trains to Harwich International connecting with continental ferries to the Hook of Holland.
It is also now the eastern terminus of the Elizabeth Line, which runs from Heathrow via Paddington though central London to terminate at Shenfield. This is now the busiest line in the UK, with Elizabeth Line trains running at a frequency of up to every 3 or 4 minutes in peak periods, Between the peaks there are a lot of ECS movements to be made to and from the stabling sidings here and at Gidea Park.
Freight services mostly consist of the long container trains running via the North London line to and from the port of Felixstowe.
The simulation includes the stretch of track from Romford (including the active Engineers yard), through Gidea Park, Shenfield and beyond Ingatestone on the main line. The full 24 hour timetable which is included contains over 950 trains!
Very busy!