Great Western electrification scheme 'one year behind schedule'
|HST Trains will continue in service until electrification |
allows new IEP trains to take over services.
The predicted cost to transform the old Great Western route has climbed from £640m to £1.74bn.
Senior industry executives have said the plans to complete the work by the end of 2016 will not be met.
Network Rail said work was "progressing well" but schedules could change.
Overhead wires need to be fitted between Reading and Oxford so that new trains can run on the line and carry more passengers, ease overcrowding, and improve rail times.
New trains are being shipped from Japan, with the first due to arrive in two weeks but they cannot be tested on the Great Western line because the power supply is not in place.
Sources have told the BBC the job is bigger and harder than expected, but also dramatically more expensive.
The first of a new fleet of electric trains is on its way from a factory in Japan, raising the prospect of brand new trains standing idle in sidings.
Officially, Network Rail is still aiming for the wires to be working late next year, but it is now suggested that the wires will not be up until 2017.