coppercapped
Established Member
I'm not sure what this is intended to imply.On GWR you’ll then need to factor in loss of performance when running on diesel.
On those sections where diesel power was always to be used - that is on those lines off the end of the electrified network - the line speed limits are such that the trains will not be able to reach 125mile/h anyway, so there will be no loss of performance when compared to an HST. In fact, with the increase in the number of powered axles and the inherent slip-resistance of variable voltage, variable frequency 3 phase drives coupled with the lack of low speed 'grunt' in HSTs the potential exists to improve the timings.
The performance will only be compromised compared to that planned on the sections that are not due to be wired in the immediate future - that is Wootton Bassett / Chippenham to Bristol via Bath and Bristol Parkway to Temple Meads via Filton Bank and the extension from Cardiff to Swansea. Only some of the first route is passed for 125mile/h and none of the latter two routes. There may be some loss in time compared to an HST when hill-climbing, which will however only affect the Up trains, but this will have to be seen in practice.
In the short term - until the Didcot to Cardiff section is energised - there will be no improvement in timings. But history shows that this is not unusual when new traction is introduced - time is given for staff and operations to become used to the new equipment and sufficient is available to enable changes to be made to the whole timetable for that route. In addition timings are such that an HST could be substituted without an effect on performance.
The issue with the Class 80X is not its technical capability but the very expensive way the DfT executed the Intercity Express Programme.