While not in the IEP league, this sighting shot raises the odd eyebrow

Published with the start of the HS2 rolling stock procurement process, the Pre-Qualification Technical Summary (PQTS) occupies a modest 38 pages, of which 16 are devoted to performance, five to functionality and four to interiors. The specification covers the 60 or so Conventional Compatible Very High Speed Trains (CCVHST) that will spend a fair proportion of their working life running on the West Coast main line when they enter service from 2026.

Readers will note that, as always, I have spelled out that last abbreviation. But throughout the specification HS2 refers to the ‘TMM’, assuming we all know what it means. Call me pedantic, but long experience in this acronym and abbreviation-rich industry has taught to expect gently chiding correspondence from readers if I spray TLAs around without elucidation (TLA? - Ed).

Three Letter Acronym. So a hint of sloppiness early on. But a quick check with the associated notice in the Official Journal of the European Union (OJEU) revealed that TMM stands for Train Manufacturer and Maintainer.

One TLA that is explained is CRN, for Conventional Rail Network. This aligns with Conventional Compatible.


Let’s start with the main characteristics of the new railway. It is being designed for a maximum speed of at least 360km/h (225 mile/h). The European Train Control System (ETCS) Level 2 will be fitted throughout and Automatic Train Operation (ATO) will be standard.

Construction will be to GC and GI2 gauges, with a nominal platform height of 1,115mm. HS2 had been trying to persuade the European Railway Agency to adopt a UK special of 1,100-1,200mm in addition to the standard 550mm and 750mm specified in the Infrastructure Technical Specification for Interoperability (TSI) plus the GB-specific case of 915mm.

The addition of the 1,200mm height was opposed by the Community of European Railways on the grounds that, if it was in the TSI, mainland operators might decide to use it, wrecking cross-border interoperability. Why such a high platform? HS2 claims that it is necessary to provide level access with the vehicle floor-height needed to accommodate the larger wheel diameter predicated by 360km/h running.

With CRN platforms built to a nominal height of 915mm, ‘but with significant variation’, the CCVHST is going to present an interesting challenge for the door designers.

Long tunnels under the Chilterns and London suburbs will be single bore and smaller than tunnels on other high-speed lines. Micro pressure-wave mitigation will be incorporated into tunnel portals.

Some ‘particular’ features of the CRN are noted. Colour light signals are protected by Automatic Warning System (AWS) and Train Protection & Warning System (TPWS), although ‘European Train Control System (ETCS) Level 2 may be fitted during the life of the rolling stock’. Given that the service life is specified at 35 years, that takes us out to Control Period 13.

Compared with the constant 5.08m height of the HS2 overhead line electrification contact wire, the height of the wire on the CRN is described with masterly understatement as ‘variable’. Pantograph compatibility is likely to be another interesting issue.

Maximum linespeeds are quoted as ‘up to’ 125 mile/h on the East Coast main line (ECML) and 110 mile/h on the West Coast (WCML). The latter is qualified as ‘assuming no tilt’ although ‘linespeeds may be raised in the future through infrastructure works and resignalling’ (‘Informed Sources’, June).

Given the lack of funding for enhancements on the CRN in Control Period 6 (2019-24), plus the fact that any enhancements funding available must go to the ECML if the step-up in paths essential to the 2022 timetable is to be achieved, CCVHSTs could be limited to 110 mile/h in 2026.

The UK’s first high-speed line: Siemens-built e320 unit Nos 374024 and 374025 exiting North Downs Tunnel on HS1 with the 12.24 St Pancras to Paris Nord service on 13 February 2017.
Jamie Squibbs
High-speed, Japan-style: Shinkansen trains side-by-side at Tokyo on 11 November 2014; JR Central unit at left and red JR East E6 series train on the right.
Keith Fender

And note that despite being described as a ‘technical document’, I have corrected those imperial speed abbreviations from the ‘mph’ that is used throughout. Am I being overly pedantic? No, in a technical document I find this lack of rigour irritating.


Demonstrating the trains’ compatibility with the infrastructure will be the responsibility of the TMM. This will be interesting on both HS2 and the CRN.

As noted previously, the 360km/h ‘anticipated’ maximum speed exceeds the technical scope of the relevant Technical Specification for Interoperability, which assumes that 350km/h is fast enough. Some consultants are going to make a lot of money extrapolating specifications to allow for that extra 10km/h. Incidentally, a leading European overhead line equipment (OHLE) supplier for high-speed lines told me recently that above 320km/h the maintenance needed increases not with speed squared but ‘exponentially’. ‘Every extra 1km/h makes a difference’, he warned.

As for the CRN, HS2 Ltd is working with Network Rail to agree interface requirements that will be incorporated into the Train Technical Specification (TTS). While compliance with these requirements ‘will support compatibility with the CRN’, the TMM will remain responsible for gaining formal agreement with Network Rail.

Talking of acceptance, at the suppliers’ day the potential TMMs were told ‘once we’ve actually got a train to work with, we’ll need to carry out extensive off-network testing to prove the capability and reliability of the design before we take anything onto the new high-speed network or our conventional network for real’. That raises the interesting question of where do you prove the capability and reliability of a 360km/h train off the network?


There are three sets of performance parameters in the PQTS that apply to both a 200m unit or two units running in multiple (404m long).

In line with current procurement techniques a journey time is specified, rather than a maximum speed. Two journeys are identified.

For London Euston-Birmingham Curzon Street the journey time is less than 45min 30sec, including stops at Old Oak Common and Birmingham Interchange stations with a two-minute dwell time at each. This represents an operational margin over the timetabled 49-min journey time.

Similarly, between London Euston and Glasgow Central via the Handsacre Junction connection with the WCML the time must be less than 3hr 45min 30sec. The PQTS notes that the journey times for two units in multiple on the CRN are still under consideration. It adds, ‘a train current limit of 300A will constrain achievable journey times for longer formations and (HS2) is therefore investigating whether the maximum line current can be increased for the CRN’. The current limit on HS2 is 1,070A.

Braking for this purpose will be the ‘ATO Maximum Brake Rate’ shown in Table 4. Maximum adhesion is assumed to be 15%.


Acceleration is the second performance parameter, with several scenarios specified. The basic requirement is for a train to reach a speed of 360km/h and cover a distance of 40km in no more than 535 seconds from a standing start on straight and level track.

Two other acceleration tests are 200km/h to 360km/h, also over a distance of 40km, in no more than 450 seconds. And 230km/h to 360km/h, in no more than 440 seconds, while covering 40km.

However, the PQTS notes that this level of acceleration will not be required until the Phase 2 timetable is introduced with its 18 trains per hour and the need to slot into the traffic in the core section of the HS2 network.


Braking is specified in terms of deceleration in m/s2. I find a percentage of the force of gravity easier to appreciate. Cant deficiency can be expressed in the same way, so the maximum lateral acceleration you should feel when curving at Enhanced Permissible Speeds is 6%g. Similarly a full service brake application with IC125 is 9%g.

I have added the %g equivalent in the two tables. Table 4 is the ‘ATO Maximum Brake Rate’ referred to above and Table 5 the ‘ATO Normal Brake Rate’.

A unit should be able to regenerate 100% of the energy from braking, after losses, at the ATO Normal Brake Rate. However, the braking performance in Table 4 must also be achievable without relying on the regenerative braking. Cue some very hot brake pads after the acceptance test.


There will be a contractual energy consumption limit to be agreed between the TMM and HS2 with incentives to reduce consumption applied through the whole-life value evaluation model in the contract. This will be based on the standard Euston-Curzon Street 49-min run, with two stops, measured over a return journey.

Energy, measured at the pantograph, will include traction, auxiliary and heating, ventilation and air conditioning loads net of regenerated energy. Energy consumed during terminal station turnrounds is excluded.

HS2’s business case is based on an assumed energy consumption of 22.6 kWh/unit-km. That figure is meaningless unless you know the duty. But to give it some context I have raided Professor Roger Kemp’s 2007 paper for the Rail Safety & Standards Board (Table 6).

Italian high-speed: Trenitalia ETR 1000, developed by AnsaldoBreda (now Hitachi Rail Italy) and Bombardier, at Florence on 10 March 2016.
Keith Fender


ID: PQTS-119 – Maximum Route Availability (§7.10.3) The Unit shall not exceed Route Availability of RA7 calculated in accordance with GE/RT8006[22]. For this calculation, exceptional payload shall include a standing passenger loading of 320kg/m².

Rationale: A payload of 320kg/m² is specified by GE/RT8006, and is separate from the Exceptional Payload used for other performance characteristics.

RF notes: Elsewhere the average passenger weight, including luggage, is given as 90kg. So HS2 is assuming full and standing loadings of 3.5 passengers per m2.

Running through the table, the first Pendolino column is measured consumption on a London-Manchester run but before the Virgin High Frequency timetable was introduced. Hard driving was not required. In contrast column 2, using modelled performance data, has an 11-car Class 390 running to the accelerated timetable, over the same route.

There are various modelled data for IC225 quoted in the Kemp paper. Roger Kemp also refers to an Association of Train Operating Companies study that gave the average for the IC225 electric fleet of 1.151kWh per vehicle kilometre. Counting the loco as a ‘vehicle’, this gives 17.7kWh/unit-km.

Bearing in mind that only the nine-car Class 390 figure is ‘real world’, readers may care to ponder why a Class 91 with no recovery of braking energy has the same unit consumption as a Pendolino with regenerative braking. Intuitively I suspect this may be attributed to the relative lack of braking on the East Coast racing ground.

But it does raise the issue of how a CCVHST, albeit a shorter formation, going harry flatters at 360km/h, can match the energy consumption of a Class 390 or IC225. I suspect we shall have to wait for the Train Technical Specification to see the route and speed profile generating such frugality.

Note that I have also included the Alstom AGV, which HS2 has used for the ‘reference train’ in developing the business case.


HS2 is flexible on gauging, a sensible move since a variety of vehicle configurations may emerge. Two reference vehicle gauges will be provided, for 23m and 25m vehicles with 16m and 17m bogie spacings. However a minimum internal cross-section for the passenger saloon will be specified.

Provided that these minimum internal dimensions are maintained, tenderers will be able to propose an alternative vehicle gauge. Possible changes could reflect running gear arrangement, static profile or vehicle length.

The trains in Spain: Madrid Puerta de Atocha high speed station on 7 February 2011 with a almost every type of Spanish AVE high-speed train visible. From right to left: Siemens-built Class 103 (Velaro E), Alstom TGV-derived Class 100 and Talgo Class 102 and 130 trains (the latter with Bombardier traction).
Keith Fender

An interesting concept floated by HS2 is the ability to match the train to different duties. The 49-min London-Birmingham dash and 3hr 30min for London-Glasgow are instanced. Ideally, says HS2, the interior design would be adaptable ‘to support changes in use during the week or even during a single day’.

Other examples of spaces that can adapt to different user needs include accommodating business travellers in the week and families and groups of leisure travellers at weekends. Similarly, providing space for ‘bulky luggage on a Sunday evening without sacrificing seats on Monday morning’.

While we’re on interiors, a thoughtful touch is the specification of minimum door widths at 900mm, 100mm more than the Passengers with Reduced Mobility TSI. The PQTS notes 800mm is considered insufficient for manual wheelchair users as it allows only 50mm per side for the user’s hands. 900mm is also required for a person using crutches or a walking frame.


This is really going to make the bidders sweat, or get the lawyers smiling. HS2’s reliability target gives a moving annual average (MAA) delay per service ‘on the HS2 Network’ of no greater than 30 seconds at destination.

That is for the railway as a whole. Train reliability assumes 60 units travelling 610-670,000km per year.

This gives a Mean Distance Between Failures (MDBF) causing a delay of over three minutes of at least 300,000km. Now the Golden Spanners awards are based on Miles Per Technical Incident (MTIN) and a TIN is generated when a train has stopped for three minutes.

So HS2 is looking for 186,000 MTIN. This compares with the current most reliable electric train on the network, the Siemens Class 444 Desiro, of 166,772 MTIN. Think on’t, as they say. It certainly rules out tilt, since nothing is so reliable as the system you don’t fit.

MDBF for a delay of over 60 minutes ‘and/or requiring detrainment and evacuation of passengers between stations’ is at least 4.3 million miles.

Reliability targets may also be specified for key components of the overall HS2 operation. Examples quoted are station stops that exceed the allocated dwell time due to a unit fault and transitions between HS2 and CRN similarly delayed.

Units may split or join mid-journey. Maximum coupling and separating time is two minutes. To minimise the impact on journey time, normal station operations will have to continue during this time.

That two minutes includes the time needed to re-configure systems into a single operational train and for the combined train to receive a movement authority. HS2 hopes that technology could allow safe and seamless automation of this process, ‘saving valuable minutes and making the service more intuitive for our customers’.


HS2 is working on the basis of 528 seats in a 200m unit, split 80-85% standard, 20-15% first. In standard class, airline seating knee room for a 95th percentile male is 80mm, or 160mm for two 95th percentile males sitting opposite each other. For first class seating the clearances are 2,540mm and 500mm respectively. A 95th percentile male is 6ft 1in in old money.


PQTS-367 – RIL First Class Catering (§9.1.9) The Reference Interior Layout shall include facilities to prepare at-seat first class meals, cooked on-board.

Alstom’s next-generation high-speed train: AGV near Florence in Italy.
Courtesy Alstom