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INFORMED SOURCES May 2007

IEP – great expectations

With the first stab at the functional specification published, the Intercity Express Programme is nothing if not ambitious

Last month, this column provided a quick run-down on the emerging technical specification for the Intercity Express Programme (IEP), the train formerly known as HST2. Now with the start of procurement, the first issue of the Functional specification is available to prospective suppliers.

DfT Rail emphasises that at this stage the spec' is indicative only. Between now and the Invitation to Tender ( ITT ) it will continue to be refined and modified. But this special issue of Informed Sources represents the most detailed description and analysis of IEP yet published.

There are two sets of criteria in the Specification – essential and desirable. ‘Essential' requirements are mandatory because they are said to be vital to achieving what are known as ‘success criteria'. In other words they are the minimum level the train needs to achieve to make the business case. Other essential requirements, emissions for example, are needed to comply with legislation or standards.

‘Desirable' requirements would make the business case even more attractive. The value they add to the business case will decide whether it is worth purchasing a capability beyond the essential requirement. By the time the ( ITT ) is issued DfT Rail will be able to indicate the value of bettering the essential requirements.

I should emphasise that the essential and desirable figures quoted in these articles are provisional and may well change as the specification is developed. On the other hand, coming on for £2million (5WM) has been spent on consultancy getting this far so, while indicative, the essential numbers ought to be fairly robust.

That said, readers may share my puzzlement at the precision of some ‘indicative' numbers, such as train weights. And the general view among informed sources is that some of the aspirations are distinctly off-the-wall.

Performance

There are three changes to the specification outlined in last month's column. All three types of train will be required to match the acceleration of a Class 220 Voyager, full stop, rather than up to 50mile/h. This is estimated to require between 10.7 hp/tonne and 13.4hp/tonne.

A Class 220 weighs 185.6 tonnes, and its four Cummins QSK 19s belt out 3000hp equivalent to 16hp/tonne. Obviously not all those horses are for traction, and it is debatable how much of that 3000hp is really needed, but I don't see the lower estimate, which is in Deltic + 8 territory, cutting the mustard.

Nevertheless, even greater performance than a Class 220 would be desirable says DfT, provided it didn't add weight. No real problems for electric traction, but unrealistic for diesel power. You could obtain more urge by putting in more cylinders, but in addition to the heavier engine everything else has to be sized up including the cooler group and fuel tanks

Maximum speed remains 125mile/h, but, again contrary to last month's report, 140mile/h is now a ‘desirable' feature, provided that it, too, does not add significantly to weight, cost or complexity. Again, easy with electric, but marginal with diesel.

Finally, reliability targets and aspirations are also more demanding than those reported in last month's column. The essential Mean Distance Between Failures (MDBF) is 60,000 miles for the diesel and 80,000 for the electric. DfT Rail's aspiration is to double these figures

Quicker

Shorter journey times than those provided by the current GWML and ECML fleets are an essential requirement. This is surprising given the emphasis on IEP's carbon footprint.

InterCity journeys have been getting shorter and slower and the ‘headline times' of the British Rail era are long gone. Only Virgin on the West Coast continues to proclaim the need for speed. Elsewhere reliability and the PPM has dominated TOC's aspirations.

But there are other ways to shorter journey times, Higher acceleration rates away from station stops, for example. Despite the extra passengers in fewer longer vehicles the aim is to maintain existing station dwell times and, ideally, reduce them.

Copupling

Flexibility is a recurring theme. Half sets splitting and joining, will improve efficiency on routes where the load decreases sharply and allow service to be strengthened in the peak. Reflecting problems with new generation computer controlled EMUs taking ages to reboot after coupling, the current essential requirement is for splitting and joining to take 3 minutes maximum and 2 minutes ideally.

As reported last month, coupling and uncoupling is to take place with passengers on board and with the doors left open if necessary. This is going to require some very soft coupling. Oh yes, and the 2-3min time allowance includes reconfiguring not only the Train Management System, but ERTMS if fitted and GSM-R radio.

Environment

Environmental issues loom large in the specification. Note that the comparator for the electric IEP is an IC225 and for the diesel version a 2+8 IC125. For the dual power train the comparator is a Class 442 with a Class 73 electro diesel attached. OK, I made that last one up up.

Energy efficiency is measured in terms of ‘per seat km moved'. This will be based on the energy consumption of the old and new trains running to the 2006 timetables on the ECML (electric) and GWML (diesel)

Currently the essential energy saving for the electric IPE is 35% with 45% desirable. For the diesel train the savings are 20% and 50% respectively. These sound pretty impressive until you remember the comparators.

Table 1

‘Furnished space' comparison

* Illustrates effect of no seats in front third of leading vehicle

How many seats are fitted in IEP is down to the operating TOC. So DfT Rail uses the concept of ‘furnishable space', that is the length of each vehicle into which you can fit seats, toilets, catering facilities or luggage stacks.

Table 1 shows the furnishable space for the diesel and electric IEPs and their official comparators. I have also added the dual power bi-directional half sets.

To date, the ban on passengers in leading vehicles has been mitigated by a combination of additional ‘crashworthiness' energy absorption and using the front third of the leading vehicle for luggage space and crew facilities.

Does this count as ‘furnishable space'? I have assumed it does for the full length trains, but show the effect of treating the front third as buffer space in the case of half sets.

Energy

Now the Laws of Physics dictate that the energy required by trains of roughly the same length at 125 mile/h will be broadly similar, since it is overcoming air resistance which dominates the power requirement. Thus if IEP and its comparators consume the same energy we can change the denominator for efficiency from ‘seat km' to ‘metre of furnishable space km',

With the furnishable length increasing from 171 for an Intercity 225 to 218 for the electric IEP, the longer train automatically reduces specific energy consumption, even before you start packing in more seats. I make this ‘free' gain in energy efficiency 21.6% for the electric IEP and 25% for diesel power.

Table 2 shows the targets plus what I term the length effect. As you can see, the diesel IEP beats its target just by being longer. The aspiration of 50% saving seems heroic, although you could massage the gain by taking the comparator as an IC125 with both Valentas overdue for a rebuild.

Table 2

Energy saving targets (per seat km moved)

Another way to reduce energy consumption would be to make the train more slippery aerodynamically. But an IC125 is pretty clean, especially when compared to a Voyager, say, with excrescences along the roof line.

Chimaera

What about hybrid operation, where the diesel power car incorporates a battery which can store energy produced by regenerative braking? I have reservations about hybrid main line stock.

First, the batteries are heavy, representing more mass to be accelerated. The more regenerated energy you store, the bigger the battery and IEP is supposed to be super-lightweight

Batteries also have their own internal losses. Thus, you get back, typically, around 60% of the electrical energy you put in.

Certainly the hybrid diesel is not a green panacea. In car technology, the much vaunted petrol-electric Toyota Prius is rated at 104g of CO2 per km while the diesel powered Volkswagen Polo BlueMotion emits 102kg There will be a chance to discuss these and other issues when Hitachi and Brush roll out their hybrid Class 43 in May.

With the electric IEP technology is on your side. Regenerative braking – returning power to the overhead line, will reduce energy consumption by at least 15%. If you add this to the length effect you get the essential reduction. As for the desirable extra 10%, that is where the fun and challenge will lie for the engineers, using a combination of skills including weight reduction, aerodynamics and packing in more seats.

Ambience

Two decades ago when InterCity was buying the Mk4 coach, it was decided to base the ride specification on measurable parameters. Previously ride had been evaluated subjectively, using the ‘Ride Index' with a scale of 1-5. Interestingly, the Mk3 coaches n the prototype HSDT had an Index of 3.2 at 130 mile/h - near the limit for passenger vehicles.

For the Mk 4 a ride specification that could be verified my measurement was decreed. To check that the Mk 4 met the contract accelerometers would measure the ride, in terms of accelerations inside the vehicle.

Ride would be measured during runs at 140mile/h (the deign speed) over a specified length of East Coast Main Line track fettled to a specified standard. The contract specified the allowable vibration spectrum and the number of exceedences allowed in detail.

From memory, Metro-Cammell just failed to meet the specification for the Mk 4, but this didn't matter because repeating the specified speed profile, and each 140mile/h run required a possession, plus maintaining track quality over a series of runs proved impossible. Thus the contract could not be enforced.

Anyway it is essential that IEP improves ride quality, compared to the Mk 3 and Mk4. This is specified as a reduction in vibration energy levels, at frequencies affecting passenger comfort, of 20%. The desirable reduction is up to 40%.

Now comes the blast from the past. To measure the improvement, vibration energy levels will be measured in five different vehicles, both for the diesel and electric IEPs and their comparators, at the same time during a 12 month window, at the same line speeds over the same section of track.

It is debatable whether Network Rail will have the track up to spec in time (see box). But if it does, I reckon the Mk 3 with the super compliant combination of air bag secondary suspension and BT10 bogie with bolster will ride like a dream and cream the newcomer.

Another echo from the past is the essential requirement for a reduction of 5dBA in saloon sound levels and, ideally a 10dBA reduction. Remember that dB is a logarithmic scale so an increase of 3dB represents a doubling.

Sound levels will be measured at the same time as the ride runs. But in the case of these measurements, the weather conditions will have to be the same. Yes, really.

British Rail Research did a lot of work on ambience and noise levels. One conclusion was that you need a certain level of ambient noise to stop people eavesdropping on their neighbours.

What interests me on both ride and ambience is that we are told that the targets are ‘essential' to the business case. Is the commercial value of being 5dBA quieter than a Mk 3 really that critical – or even quantifiable?

Not for the first time this initial specification, reminds me that it is preferable to be approximately right as opposed to precisely wrong. As we will see in the next section, ‘essential' train weights are specified to the nearest tonne.

I have a nasty feeling that we have seen this all before when the unique specifications of state-owed BEA and BOAC helped wreck the civil aircraft industry.

Continues.........