The three Mk3b BFOs and the 'Electric HST'

[USRailFan]

I've seen a couple of references that the three Mk3b BFO carriages that are now used as seating cars in the "Night Riviera" sleeper, were originally intended as intermediate carriages in the 'Electric HST' but ended up being finished as ordinary loco-hauled Mk3s. At first I thought this was a reference to the HST sets that were used as 'DVTs' with Class 91 locos, but that most likely can not be the case, since the three BFOs are built around 1986, and the buffered HSTs didn't get converted until about 1990, and besides there were more than three sets, and they already had their ordinary HST intermediate cars... I doubt it can be a reference to the APT either, since the intermediate cars of those were quite different... So what was this 'Electric HST' project, and how far did it advance?

[ianmacmillan]

The 3 BFOs were built for the Blackpool to London service when it was found that the standard 12 coach sets would not fit the platform at Blackpool.

While they were under constuction, alterations were made at Blackpool and to stock diagrams which made them redundant when they emerged.


The electric HST was an idea to substitute electric power cars for the HST diesels.
Tests found that, at high speed, the leading pantograph set up a wave in the overhead wire which caused excessive arcing on the rear pantograph.
The introduction of DVTs killed the idea.

[Kromaatikse]

AFAIK, these induced waves are the reason why high-speed continental railways use compound catenary. It may also help that trains with two electric locomotives (eg. Eurostar/Eurotunnel) are very long, much longer than a HST set.

For contrast, the Finnish railways use conventional catenary and the commuter trains have a pantograph for every two carriages, but these do not exceed 100mph. There is a similar situation for the relatively few multiple-headed heavy freight trains (eg. three electric locos on ex-Russian iron ore).

The 91/DVT combination seems to have been a good solution to the need for an "electric HST".

[MoonKid47]

OT: The title of this thread sounds like a railway sitcom!

[Grumpyoldman47]

I was involved with both of these BR projects, and the above information does not match how I remember them. However, I must acknowledge that both projects were being developed/taken forward roundly thirty years ago, and the following may be wrong in minor detail, but not in substance.

Although it may have been the intention to use the Mk IIIb BFOs on the Blackpool - Euston service, that is not the reason for their construction. The Mk IIIb BFOs were to be used with Mk III loco hauled coaches when traveling at 125mph; on a HST, brakes are applied from each end of the set, and the BFOs were to have been fitted with equipment which would replicate this process by applying brakes from a second location in a train when it was being pulled by a single loco (say a class 89) at speeds above 100mph. Without the BFO and its equipment, operation at 125mph would not have been possible without increasing signaling distances.

The electric HST project was not (so far as I recall) connected with the Mk IIIb BFO project in any way; its purpose was to speed-up the WCML, but I guess if it had been taken forward either more Mk IIIb BFOs or loco-hauled equivalents of the HST TGS would have been procured.

Remember, the prototype HST comprised power cars and loco hauled Mk IIIs, and this concept formed the basis of the electric HST. The WCML had a fleet of Mk IIIs hauled by locos, and DVTs hadn't yet been built; an electric HST power car would have been coupled to either end of a rake of loco hauled Mk IIIs, and thereby would have replaced the class 86s and 87s on front-line services. They would have been viewed as locos, and would have been numbered in the 92XXX range. They would have looked very much like diesel HST power cars with a pantograph, the major external difference being that they would have had side buffers built into the lower front fairing; in turn, these would have been encased in quite large fairings, and comprised within these would have been various electrical/etc connectors. These would have been used for the complete sets (2 power cars + Mk IIIs) to have been dead-hauled by a diesel loco on non-electrified lines; the specification would have specifically mentioned Inverness as a potential destination (this was in the days of the 'Clansman' Euston - Inverness service), and the Cumbrian Coast line as a diversionary route (the future of the Settle - Carlisle line was uncertain at the time of this project).

The project was eventually dropped because BR could not justify two projects for new electric traction at the same time; the class 89 was therefore taken forward (from memory, this pre-dated the electric HST project). A model was made of the electric HST power car (and presented to the BRB Investment Committee), but I don't know if it survived privatisation.

I can't remember problems caused by two pantographs (one at each end of the train) being in contact with the overhead line ever being discussed at project meetings, although I can't be 100% on that. With hindsight, if it wasn't it does seem rather surprising as the two power cars of the APT-S trains were to have been coupled together so that they could be connected by a high voltage connection, thereby permitting just one pantograph to be used at any one time; this was deemed necessary because - at that time - it wasn't possible to provide a high voltage connection from one end of a train to another - and (as has already been pointed out) tests had shown that the leading pantograph caused movement in the overhead, leading to excessive arcing for the rear one.

I've often thought it a shame the electric HST didn't go ahead instead of the class 89 project. Its difficult to be precise about timescales (as I said at the beginning, this did happen about thirty years ago and I haven't any notes to refer to for clarification), but I guess this was soon after the abandonment of the APT-S project, and although the WCML was modernised with class 90s and DVTs, the maximum speed was to remain at 100mph until the arrival of the 'Pendolinos'. With hindsight, this was the first set-back for a continuous improvement process for the WCML, the second being the abandonment of the IC250 project because of privatisation.

[bdy26]

The BFOs took up normal use on the WCML sets, and IIRC were generally marshalled in the longer pullman formations of the mark 3 sets. a mk1 BG was still used, but the guards preferred the mk3 office to the mk1!

The Eurostars borrowed by GNER were allowed to run with 2 pantographs, but despite the length of the consist were limited to 100mph in part due to the setting up of a wave on the wire. The overhead on CTRL is apparently more highly tensioned.

B

[pendolinobasher]

OT: The title of this thread sounds like a railway sitcom!

Or a funny sounding band

[passedcleaner]

The 2+18 Eurostar sets are allowed to run at full speed with both pantographs up because of the sheer length of the train - i.e. the compression wave settles before the rear pantograph hits it! Plus Eurostar was designed before a continuous 25kV cable along the train roof was legal in the UK. I believe this restriction is now lifted for segregated HSL running - hence the possibility of 'foreign' TGV / ICE trains running to St Pancras.

Seb