Chiltern Railways has discontinued its call for proposals for the supply of a fleet of battery-electric multiple-units. In September 2022 the operator invited proposals for the supply of between 30 and 70 new, existing or converted BEMUs. However, the procurement process was not progressing, and on August 13 Chiltern confirmed that it had been stopped.
Rail Business UK understands the decision was taken because of changes to Department for Transport processes for making the case for ordering new trains and because the technical requirements have changed. The operator now has a better understanding of the difficulties of accessing the national electrical supply grid along the Chiltern route.
It would be interesting to know more technical details of why Chiltern considers using Underground 4th rail as not practical on shared sections.
If electrical power to support BEMU/with in motion charging is a problem for the next generation of trains, then Chiltern should be required to implement a hybrid BEMU/DMU design that is battery powered inside the M25 (maybe with opportunity charging when stabled/waiting at Marylebone) and then diesel traction and recharge outside of London (with additional battery traction used in major built up areas where possible)
My idea was we might have overhead electrification Marylebone – Aylesbury via Princes Risborough and Aylesbury – Amersham, running on battery for the 24 mins between Amersham and Harrow. I wonder want the issues with the power supply are, the route does parallel HS2 for a little way, although there would be high loads south of Harrow and north of Amersham as the batteries are recharged. I imagine the fourth rail might struggle to do this while running the Metropolitan line service.
My idea would be to fully 25kv it including the LUL section which would see both electrification systems be completely electrically separate as the fourth rail has it is return in the form of the central rail and the OLE has it is return in the form of the running rails which are insulated from one another.