FROM THE ARCHIVES: Class 91s...promise unfulfilled


  • This feature was published in RAIL 869.

The ill-starred Class 89 never progressed beyond one prototype (RAIL 847). This was down to a fresh look at electric locomotive requirements, after the curtailment of the Advanced Passenger Train (APT) project in the summer of 1983.

In addition to Class 89, British Rail (BR) had also authorised the design and production of four High Speed Train (HST-E) power cars purely with electric traction equipment for trials on the West Coast Main Line (WCML). The thinking was that the mechanical parts had been proven in the diesel version and that HST-E, plus Mk 3 coaches already on the route, would provide a 125mph trainset.

The InterCity 225 Study Group was then formed to develop a new traction project named InterCity 225 - the digits referred to the planned top speed of 225kph (140mph). InterCity had decided on the ‘stretch’ (the term used for the increase beyond 125mph) to 225kph for the proposed new locomotive and coaching stock following strong lobbying by BR’s Director of Mechanical and Electrical Engineering (M&EE). The group developed a strategy study for high-speed West Coast Main Line electric trainsets that included Mk 4 tilting coaches.

The group submitted a proposal to BR’s Strategy Committee in October 1983 for an 80-tonne Bo-Bo machine for the WCML, but it was thrown out as inadequate in many aspects and the directors of InterCity, Engineering, Projects and M&EE were told to do better!

As already noted, within the last two years, the BR board had approved the ordering of a prototype 125mph Class 89 as a precursor for a fleet of at least 30. This design formed part of BR’s submission to the Department of Transport (DTp) for East Coast Main Line (ECML) electrification, which was eventually approved in July 1984.

The Strategy Committee quite rightly queried why the new super Bo-Bo had not been put forward in place of Class 89 and HST-E. When the former had been proposed, a machine with a four-axle wheel arrangement was judged inferior to one with six in relation to haulage over the northern banks on the WCML, and the Strategy Committee queried the volte face in the new proposal. The committee also wanted to know how it fitted into a multi-sector strategy for electric traction replacement.

The situation with AC electric traction was descending into a farce. The remaining 62 examples of Classes 81 and ‘85’ from the first phase of procurement in the 1950s were now very unreliable, and failed five times more frequently than Class 87 - itself nearly ten years old. A shortage of traction ruled out withdrawing these veterans.

If the APT had been put into commercial service on time, then locomotives would have been released - permitting elimination of the unreliable types.

Class 89 was the motive power included in BR’s proposal for ECML electrification and regarded generally as a low-risk multi-purpose machine that would offer superior tractive capability over the WCML’s northern banks.

Concurrently, there was a concept for a dedicated freight locomotive, dubbed Class 88. But in the new era of sectorisation in 1982-83, none of the sector directors were willing to sponsor the project.

In December 1983, the Strategy Committee considered a fresh submission from the InterCity 225 Study Group on InterCity traction for the WCML, with ECML electrification still awaiting DTp approval. Electric HST power cars were now ruled out because of inflexibility for use on night parcel and freight services, yet less than a year had passed since the BR board had sanctioned four prototypes. Not long afterwards, the HST-E project was cancelled.

Class 89’s speed potential of 125mph south of Crewe was said to be minimal and offered no advantage over Class 87 because it was still limited to 4.25° of cant deficiency (in very simple terms, the permissible speed a curve can be traversed without undue sideways motion, where the higher the value, the faster a curve can be traversed). This had been accepted at the time of the prototype’s authorisation in 1982, but it was its superior haulage capacity over the northern banks compared with a new Bo-Bo electric that had been decisive.

The issue of slipping by a four-axle machine under poor rail conditions on these banks was not mentioned in the new submission to the Strategy Committee. The proposed InterCity 225 would be lighter (and so more fuel-efficient) than the ‘89’, and also offer greater flexibility in deployment.

Aside from the technical and operational points referred to, the financial appraisals that accompanied the latest submission also ruled out Class 89 and HST-E on this basis. However, earlier financial appraisals had made these designs “best buys”, and it was no wonder that the DTp was always sceptical of BR’s financial and traffic estimates.

The study group concluded that, on best case assumptions, the InterCity 225 with tilting coaches and capability of 9° of cant deficiency (the same as the APT) was the only option for the WCML, while on worst-case assumptions the design offered no advantage over an updated Class 87.

For the East Coast, there was “little to choose” between the InterCity 225 and Class 89 for running up to 125mph, but the former offered the stretch up to 140mph. Selecting it for this route would offer compatibility with WCML traction and reduce development and other costs. For a route already operating at 125mph, the 110mph Class 87 was clearly ruled out, while HST-E had a poor financial score.

The study group went on to recommend that the two sets of HST-E power cars and Class 89 prototype already authorised should not be cancelled because each would serve as back-ups for the WCML and ECML respectively, should InterCity 225 fail.

The HST-E project was, however, quickly cancelled. And when Brush Traction learned that Class 89 was unlikely to be replicated, it effectively ceased design work on 89001 while the company concentrated on an overseas order instead, which later cost it dearly in late-delivery penalties levied by BR.

The next stage involved the issue of a pre-qualification document to interested parties, which provided background information about the InterCity 225 project. The traction unit was for the WCML and would have to perform mixed-traffic duties - day and night passenger, parcel and mail, and haul 750-tonne freight over Shap and Beattock overnight. Haulage of both tilting and conventional rolling stock would be required. Top speed would be 225kph, the maximum cant deficiency would be 9° without the provision of tilt equipment, and the maximum unsprung mass would not exceed 1.8 tonnes.

BR said it was prepared to enter into a sub-contract with the successful bidder for the supply of technical information, advice and testing.

Arising from lessons learned with APT’s design work and general project management, the view was firmly that (like Class 89) the design and building of the InterCity 225 should be put out to competitive tender and not just awarded to British Rail Engineering Ltd (BREL) - BR’s workshops subsidiary.

By spring 1984, the traction and rolling stock element of the submission for ECML electrification was being reconsidered. A tilting coach, designated Mk 4, was now seen as a better option than the existing Mk 3 and would mean a single design would suffice for the ECML and WCML.

Nevertheless, in June the director, InterCity stated Class 89 was for the ECML, with InterCity 225 development for the longer term for both East and West Coast routes.

BR sent the prequalification document to BREL, Brush Traction and the General Electric Company (GEC), as well as Alsthom Atlantique (France) and Krauss Maffei (Germany). The question then arose whether to add Japanese and US builders.

The board was split. One faction wanted as broad a competition as possible, due in part to an unenthusiastic view of British contractors - they were viewed as lacking experience in high-speed design. The engineers, on the other hand, wanted to limit the circulation of their research because they regarded themselves as world leaders in bogie design. Once third parties took over responsibility for design, the engineers realised their claimed pre-eminence would be lost. BR’s Policy Adviser put the position in context by saying the pre-eminence only related to design for BR track.

Government departments were consulted on their attitude to an order being placed overseas. Aside from the obvious points about linguistic and logistical issues, awarding an order such as InterCity 225 to a foreign bidder was seen as certain to result in “dire” political consequences, and that BR would need to present a cast iron case for the decision, demonstrating an extraordinary advantage over the UK competition.

The study group reported again to the Strategy Committee in July 1984, admitting changes of principle to what the latter had approved in December 1983. At that time, the committee viewed InterCity 225 as a ubiquitous traction unit with a built-in capability to operate over the DC third-rail network to the Channel Tunnel, but this was not now envisaged. The implication was InterCity 225 would not replace life-expired DC, as well as AC, locomotives.

Additionally, InterCity 225 was not now expected to match Class 87 freight haulage capabilities over Shap and Beattock. As previously noted, this haulage capability, a deciding factor in the order for Class 89, had not been brought to the attention of the Strategy Committee in December 1983.

Overall, InterCity 225 was no longer regarded as the ‘go anywhere, do anything’ design envisaged previously. The size of production run would determine how the design and development costs could be apportioned and hence the resultant cost per locomotive. Quantifying the production run was now problematic.

The InterCity 225 case to be the future standard electric design was weakened even further by other developments. The initial order for the WCML had been based on replacing the surviving 62 first-generation classes. A separate submission for the design and construction of Driving Van Trailers (DVTs) had, by now, reduced the InterCity 225 requirement by 14.

Secondly, a further submission was in play for 25 Class 87/2s (later Class 90) which cut the initial InterCity 225 number for the WCML even further to just 13, of which eight were to be prototypes in order to establish the design for differing duties and routes.

Anglia electrification would eventually absorb 19 machines from the WCML, replaced there by InterCity 225. Without explanation, the submission said eight diesels working under the wires would need ten electric replacements and ECML passenger provision would absorb 31 traction units. Transferring a similar quantity of ‘87s’ from West to East Coast lines for freight work would then be back-filled by more InterCity 225s.

Having reached this stage, the next hurdle within BR’s labyrinthine committee structure meant the project had to go before the Business Engineering Group, which (among other things) would determine its priority for resources. This was before a submission to the Investment Committee, which made recommendations to the BR board.

Even if all these hurdles were crossed, there was still the small matter of DTp go-ahead to be received, which in turn depended on HM Treasury putting up the money!

All the running thus far had been led by InterCity. In August 1984, the DTp asked for the views of freight businesses concerning the use of InterCity 225. By way of reply, the Director of Operations expressed satisfaction concerning the suitability of the proposal in offering flexibility in traction allocation. Nevertheless, the freight business refused to fund the upgrade to InterCity 225’s traction equipment to make the haulage capability equal to the proposed Class 90.

The Department also queried a production build without a prototype, but BR explained that the APT power cars had proved 90% of the technology planned for InterCity 225. By now, the talk was of 31 examples for the ECML in substitution for Class 89, on top of 25 for the WCML. There was also a proposal for an asymmetrical body design, with one cab styled aerodynamically and the other effectively vertical to match a coach end.

Outline schedules gave an InterCity 225 running at up to 125mph and with tilting coaches an 11-minute advantage over a 100mph Class 87 between London and Manchester and 37 minutes to Glasgow.

By the end of September, the plan was to go out to tender early in 1985, despite the WCML tranche and the substitution for Class 89 on the ECML having yet to be authorised. There was talk of the successful contractor having two production lines, one for each build. After the successful proving of a specified number of pre-production locomotives, the main build would be delivered by May 1991.

InterCity 225, the traction element of which was now designated Class 91, was described as an InterCity electric traction strategy, rather than the future design for all AC electric applications, which was how it had been presented to the DTp.

More number crunching showed that InterCity 225 without tilting coaches offered no advantage over Class 90 on the WCML, perhaps because both were specified as 5,000hp machines.

Inexplicably, an investment submission including Mk 4 tilting coaches for the WCML would not be ready before autumn 1985 - two years after the first proposal to the Strategy Committee! Consequently, it was agreed to press ahead with just the ECML proposal.

As the end of 1984 approached, matters began to crystallise. InterCity wanted Class 91 in place of Class 89 for the ECML, and the DTp needed to be persuaded of the rationale for the change. The timescale for tendering and then building Class 91 in order for it to be ready for the anticipated completion of East Coast electrification to Leeds was getting very tight.

Five reasons for opting for Class 91 over Class 89 were:

  • There was no difference in the timescale for production of both types.
  • Class 89, as yet unbuilt, was unproven, whereas the APT power cars were performing well and technology from these was expected to be used in Class 91.
  • Body mounting the traction motors would reduce unsprung mass and offer lower track wear than Class 89, and would use less power -making it more economical.
  • Class 91 had a stretch capability to 140mph.
  • There would be a common design for both ECML and WCML InterCity services.

It is worth noting, however, that BR’s financial appraisals showed no advantage of one type over the other at that point. Of course, the Class 89 cost was known, whereas that for Class 91 was an estimate.

It was also claimed that the ‘91’ would be as effective for freight haulage as the ‘89’, which it clearly would not be by having to transmit the tractive effort through only four axles, not six. This was despite admitting that Class 89’s superior low-speed tractive capability and higher power than Class 91 at that time meant it was faster between King’s Cross and Leeds and from Newcastle to Edinburgh.

The BR board approved the substitution of Class 91 for Class 89 for the ECML at its meeting on February 14 1985, but with strong reservations about the proposed timescale and the need to ensure that the technology was “mature”, even if this was foreign.

DTp approval came the following month, and this allowed tenders to be sent to Brush, GEC and also the General Swedish Electric Company. The latter had already struck up a relationship with BREL but, notwithstanding this, GEC offered BREL a sub-contract for the mechanical parts construction, if it was successful.

Following a difficult tender process, GEC was awarded the contract for 31 locomotives, with an option for a further 25 for the WCML, in February 1986. And BREL set up a production line at its Crewe works.

Prior to the award, and with BR’s intimation to industry that it would require over 110 electric and up to 50 Type 3 diesels in the medium term, GEC enquired about buying Crewe works, but nothing came of the idea.

Comment as guest

Login  /  Register


No comments have been made yet.

RAIL is Britain's market leading modern railway magazine.

Download the app

Related content