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INFORMED SOURCES September 2001

Voyager impresses - Pendolino deceives to flatter

Useful miles in Voyager and a couple of blasts in Pendolino really brightened things up

Let's get one thing clear before I write about Voyager and Pendolino. Virgin is the worst organisation on the planet, Virgin's two rail franchises offer uniformly unspeakable service and the sooner they are handed over to Connex the better and, as you could tell from the expression on my face in last month's issue, discovering that someone had put my name on a locomotive in Virgin livery caused great personal distress, requiring counselling.

I say all this because when I wrote in glowing terms about Pendolino back in the April issue I received a storm of protest that I was going soft on the Red Empire. And an old chum begged me not to swallow everything Virgin said and leave room to backtrack when it all ends in tears.

So what follows had been written with the Office 2000 cynicism adjuster (you find it under Tools/Opt1ions/Properties/Style/Emotions) set at 150%. Anything remotely favourable is down to me being a pushover for a shapely nose cone.

Big diesel experience

First Voyager. What you all want to know is whether you can tell that there are 19 litres of Cummins QSK19 diesel engine pumping out 750hp under your feet. And the answer is ‘yes, but only if you are a failed diesel development engineer trying hard'. Sound insulation is excellent. At idle the air conditioning was noisier than the engine.

My first run from Euston to Watford was out of Platform 18 with the cutting wall alongside and several bridges and underpasses. These were ideal conditions for noise to be reflected back from the hard working engine under the floor. Think Class 165 leaving Marylebone. But Voyager, with everything sealed up and insulated, kept the noise out.

At the other end of the speed envelope, at 125mile/h on the Great Western main line, you didn't know there was a diesel on board.

Obviously, with all the Cummins' bits spinning around happily at speed, it ought to be smooth. And it was only when the driver notched up from coasting that I could feel the vibration from those six big pistons revving up. It wasn't unpleasant, rather it was a low growl felt through the floor and the back of the seat.

And, of course, thanks to the Alstom Onix three phase drive, the Cummins is spinning at its optimum speed most of the time and there are no ‘gear changes' as you get with hydraulic transmission. These can be quite objectionable on some Turbostars as the low engine speed sets doors and trim vibrating.

Firm ride

When we got onto the GWML, the ride felt firm and more- damped than my usual reference, the Mk 3 coach. There was also some liveliness over crossings.

After Reading it was up to 125mile/h and the ride was excellent. My notes record it as ‘firmer than a Mk 3, smoother than a Mk 4'. Before you scoff at the Mk 4 comparison, remember that its ride is still improving at 125 – or it was in the days when a real railway could demonstrate trains at 140mile/h.

But when Voyager stopped fumes from the hot disc pads were sucked into the air intakes. When I drew this smell to the attention of my chums from Bombardier, they tried to persuade me that I had chosen to travel in the one aberrant coach. As the smell was also present on my later MML run, I reckon it is a feature rather than a bug.

Another go

On 9 July it was time for my second Voyager run, this time from St Pancras to the Old Dalby test track where Pendolino PS02 awaited.

Sitting in mid car, once again in Standard Class, I could just feel the idling engine under my feet. There was the familiar ‘growl' as the load came on but once on full throttle, and positively sprinting out of the station, the engine noise and vibration vanished.

Now the MML is not the best bit of track on the network but the well damped suspension coped. As the speed rose there were occasional signs of busy-ness – that sense of the primary suspension working that you get in a Mk 4 but not a Mk 3.

On one particularly poor section of track, even Voyager's high tech B5000 bogie was caught out and there were a series of bumps that caused some of the trim to buzz. And when we stopped at Bedford , there ‘Odour of hot brake pads' again.

On the return journey I sat at the rear of the train over the bogie and my notes south of Leicester read, at various times, ‘busy', ‘lively' and ‘rough over bogie'. These are interjections in notes of interviews during the journey, as opposed to sitting there concentrating hard in ‘human ride meter' mode.

HST comparison

By chance I went to Derby by IC125 a few days later. Both out and return journeys arrived early - by 3min and 5min respectively. I was not surprised, given the fact that the suspension had been on the lateral bump stops at the usual extreme curving rules locations.

On a long journey I suspect the Mk 3's more spacious interior, subjectively wider, softer seats and general ambience would give it a slight edge over Voyager. The Mk3's suspension still has a unique ability to retain its composure on Railtrack's worst. That said, the Voyager's bogie has yet to be fine tuned.

In Voyager's favour are modern facilities for the disabled, at seat entertainment, some very impressive electronic aids for the train manager, very deep windows, a superb build quality and seats which, I am sure, are very good for your back. Oh, yes, and blistering performance.

A five car Voyager has 450hp more than the legendary Deltic plus 8. That's about 14hp/tonne, with acceleration from zero to 60mile/hr quoted at 59 sec. This is an acceleration of 4.5%g, half the maximum <Ital>braking<ital> rate of IC125. Tests up Dainton bank at full throttle had Voyager running at the 60mile/h line speed where an IC125 would be at 45mile/h.

Overall, I am sure that familiarity will breed content – but reader's impressions will be welcome. I find it's not until I use a train routinely that the definitive view emerges.

Pendolino poser

At Old Dalby on 9 July (Alstom keep changing the name so let's stick with the pre-revolutionary title) Pendolino PS02 awaited. The plot was that guests were divided into blue and red parties and each party would have a test ride while the other enjoyed a champagne buffet. As a ‘blue' I was on the first demonstration.

For each trip PS02 ran back from Old Dalby site, through Grimstone Tunnel to Asfordby at the end of the track where the driver changed ends. For the test run proper we accelerated to 105mile/h past Old Dalby and held this speed through four curves before accelerating to 125mile/h briefly before braking.

Alstom has laid Old Dalby with track representing the gamut of the WCML experience, from jointed rails (!) to BR 113a and UIC 60 continuous welded rail with a range of fasteners on timber concrete sleepers and steel sleepers.

On Run 1 we had reached 60mile/h when ran onto the first length of UIC 60 rail. Pendolino was so smooth you wondered why people bother with mag-lev. Exiting Grimstone Tunnel at about 100mile/h on marginal track, the wheels had that ‘busy' sound already mentioned but the ride remained good.

Lateral jerks

At 105mile/h we hit the first curve and the lateral jerk was worse than an HST on the bump stops. In the next curve we 50 penced (threepenny bitted in old money) taking several bites at the transition. And there was another lurch into the curve after that.

These were big lateral g forces, but once past the transition the ride in the curve was excellent. Yet even allowing for the fact that the train was limited to 6degrees tilt angle (it will be 8 degrees in service) not a lot seemed to be happening in the tilt department.

Only once did I notice the characteristic effect of the horizon moving up and down the window. And what I saw could have been down to cant. Certainly, it wasn't as dramatic as the Advanced Passenger Train or Pendolino on home turf.

Discussing this first run with some Alstom chums they explained that there had not been a full scale track recording run which would probable indicate the need for some realignment of the transitions. And the track was also due to receive its final tamping, to the condition of the WCML in October 2002, later that week

Our Health ‘n' Safety briefing had emphasised that we must remain seated at all times. So on the return run I made a point of standing up as we curved to exaggerate the effect of tilt on the body by pivoting round the knees instead of the hips when seated.

‘Have to hold on in transition' I noted, adding ‘but I'm writing this'.

Try again

Hiding my blue badge I bluffed my way onto the second run, still trying to work out what had happened first time round. This time we were doing 80mile/h on the UIC section and I noted ‘Excellent ride, better than first time it GLIDES'.

At 90 we left the CWR. Subjectively the ride then seemed less busy than the first time. Tilting through the curves was a repeat of the first run, although I was ready for the lateral jerks.

Which all left me thoroughly puzzled, to the point that I began to develop a conspiracy theory on the way home. It went like this. Once into the curves, it didn't feel as though we were tilting to 6 deg; the movement of the horizon seemed the sort of thing you would see on canted track anyway; so had the tilt been switched on?

To turn this into a shock horror story I had to determine the cant of the test track curves. ‘They aren't canted because we want to maximise the tilt', Alstom told me. And it all fell into place.

Preview

In the beginning, the theory of tilting trains was that an accelerometer on the bogie bolster would measure the centrifugal force in the curve (lateral acceleration or lateral g in techie-speak). The control system would use this signal in a closed loop to tilt the train to the angle required to reduce the lateral acceleration to nil.

That worked fine in the curve, but to get there from straight track you had to negotiate the transition in which cant gradually builds up. And when a tilting train going molto presto hit a transition curve it took some time for the acceleration to reach the point where it registered An output. As a result, the tilt came on after the curve had started and passengers got a dose of centrifugal force.

Why not make the accelerometer more sensitive? Well, as APT demonstrated, when the train traversed turnouts at walking pace, the slight lateral acceleration would be detected and the tilt would come in.

So we got ‘preview'. This meant inter-connecting the tilt system on each coach in the train. When the accelerometer on the first coach detected a curve it sent a message down the train telling the other coaches to start tilting. It worked a treat, to the extent that if you weren't looking out of the window in APT you didn't know you were tilting. This caused tilt nausea, hence the move to partial compensation.

This still left the leading coach without any warning. Fiat came up with the deceptively simple solution of an inclinometer on the leading bogie at each end.

This instrument detects the transverse level of the track. On the straight, the track is level so the output is zero. But as the train enters the transition curve, the track starts to cant. This is detected by the inclinometer and this output causes the control system to apply a predetermined angle of tilt. Then the accelerometer kicks in and takes over as before.

Standing in the cab of a VT612 tilting diesel multiple unit in Germany a few years back, I could feel this two stage application of tilt as we entered curves.

So, at Old Dalby, with no cant for the inclinometer to work off, PS02 was running blind. I also suspect that without a canted transition curve, the accelerometers were having to deal with a much more brutal onset of lateral acceleration.

From which, my provisional view is that if the tilt is that good under such artificial, not to say extreme, track conditions it should be pretty convincing on the West Coast Main Line. Whether it will match that amazing inaugural run in APT, when tilting through the northern fells by moonlight was more like low level flying than train travel, remains to be seen.