There's a lot of misunderstanding about what phase of IEP introduction we're at.
At the moment, all the units are with Hitachi, undergoing their acceptance testing. That is done on a handful of core routes which provide the test conditions required for the test. There's no benefit to testing in Cardiff or Scotland or on the Cotswold line at this stage because they don't offer any differences over the existing test areas. Hitachi are not responsible for any kind of route proving running, that will be down to GWR and VTEC once they have units and qualified drivers on their books.
Once Hitachi have finished their acceptance testing the units will be delivered to GWR and VTEC. Traincrews will learn the traction and THEN (and only then) will we see route proving testing. It will likely be done overnight as it involves extended dwell times at stations checking stepping distances, DOO equipment and so on. Only a small handful of return trips will be required over each route.
The interference issue is delaying delivery to GWR, which was due to happen around about now.
