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INFORMED SOURCES June 2006

Virgin bids for higher speed

Sir Richard may aspire, but HMRI will decide

When Virgin announced that it had asked Network Rail to look at the costs and benefits of running Pendolino's at 135mile/h on the West Coast Main Line my immediate reaction was to ask whether they had spoken to HMRI. That they hadn't struck me as distinctly odd.

In the press release which formally launched the initiative Virgin claimed ‘while speeds of 140 mile/h and above will require new trackside signalling linked to in-cab signalling equipment on the trains, trains can operate at 135 mile/h using existing signalling'. To which the answer is, ‘not according to HMRI'.

Just to make sure, I asked HMRI, now part of the Office of Rail Regulation for their current view on speeds above 125mile/h on existing lines. As of 25 April ‘ our position is that human factor considerations indicate that optical sighting of signals cannot be relied upon at speeds over 125m/h'.

Which was as I thought, because we went through all this back in the 1980s when InterCity specified the East Coast Main line electrification for 140 mile/h. The overhead line support masts were configured to allow the future addition of a compound catenary and the traction and rolling stock was deigned for the same speed.

British Rail also proposed using flashing green signals to provide a fifth aspect a technique, known as ‘preannonce' (acute accent over e) by French Railways when the Capitole pioneered 125mile/h running on classic lines in the 1960s. A flashing green aspect would indicate that a train could run enhanced line-speed, 140mile/h on the ECML, to the next signal. A steady green aspect would require the driver to brake to line speed.

While 22 miles of the ECML between Helpston and Stoke was fitted with flashing green aspects, its use was limited to high speed testing for IC225. And that was that. Testing apart, HMRI decreed that above 125 mile/h cab signalling was mandatory.

Back to the present day, and Virgin is arguing for 125 mile/h on the basis that in France TGV run at 220km/h (136.6 mile/h) on classic routes. But there is one big difference between France and Britain . In addition to preannonce, the French network has Automatic Train Protection (ATP) in the form of KVB.

So the key issue is the reliability of signal sighting as speed increases. According to Informed Sources, since privatisation, a joint study by Network Rail and First Great Western confirmed that signals and lineside signage become progressively less recognisable at speeds above 115 mile/h.

Technical

Now, I could delight readers of an operational or technical frame of mind with an analysis of signal spacings and braking distances at higher speeds, and probably will if Virgin's aspiration achieves a positive rate of climb. But for the present it is sufficient to say that there are no technical reasons why trains could not run at 135 mile/h on the West Coast or even 140mile/h on the East Coast. And technology has advanced since the 1980s.

For a start brakes are much better. Current practice is for drivers to use ‘Notch 2' or 6% g, as the everyday maximum.

This compares with the 9%g, which enabled disc-braked IC125 to run at 125mile/h within signal spacings established for 100 mile/h tread braked stock. The Train Protection & Warning System (TPWS) is based on an enhanced brake application generating 12%g.

If maximum braking is needed only in the event that the driver misreads a signal at enhanced speed, then SPAD studies suggest that this will be a relatively rare occurrence. In which case magnetic track brakes, which clamp a bogie-mounted steel skid onto the rail head, will provide even fiercer deceleration.

TPWS is the second technological advance. With the safety lobby vociferous, it has been fashionable to pooh-pooh TPWS as good for only 75mile/h and thus a wholly inferior cheap substitute for ‘proper' ATP. But the principle can handle any speed you care to nominate.

TPWS+ has been installed for 100mile/h operation at critical locations. If needed TPWS++ could extend coverage up to 125mile/h and, theoretically TPW+++ could be used with five aspect signalling to monitor speed after a steady green. After all, the risk addressed in the HMRI's limit of 125mile/h is that a driver travelling at the enhanced line speed misses a cautionary steady green signal aspect.

Then there is the Tilt Authorisation and Speed Supervision (TASS) used by Pendolino – which is essentially a special purpose version of ATP using ETCS technology. Balises (radio beacons0 on the track authorises the enhanced speed through curves and the system intervenes if this speed is exceeded.

Driven

So there is no shortage of ways for trains to run at above 125 mile/h on existing tracks. The only question is why Virgin did not start by asking HMRI, privately, for its current stance on enhanced speeds and then work out some technical strategies.

I suppose the answer to this is that the 135mile/h aspiration is driven by Sir Richard Branson and such masters of the universe don't do boring reality, demanding instant gratification. Unfortunately transport systems involving four hundred tonnes of train full of squashy bodies and unimaginable quantities of kinetic energy don't do ‘instant'.

That said, it is absolutely the right time to make the challenge. The Office of Rail Regulation has just taken over responsibility for the HMRI. One reason for the transfer was the hope that combining economic and safety regulation would lead to more rigorous cost benefit analyses of safety expenditure, where HSE, the previous safety regulator, was seen as arguing for safety at any price.

That assumption looked to achieve ‘less bad' outcomes, but in the case of enhanced running speeds, the effect would be positive. ORR would have to consider the commercial benefits from faster running and trade them off against the risks.

Not an easy case to make, and not a ‘single bound' process, but worth pursuing. And Informed Sources suggest that HMRI internally might be more flexible than the formal response to my blunt question suggests.

Savings

Virgin reckon that ‘Trent Valley 135' would save ‘in the region of three to four minutes' – although even my most optimistic calculations can't get above 1.8min. But with a journey time elasticity of 0.85 a 4min saving on current timings from 135mile/h running would equate to a 2.5% increase in ridership on the key London-Manchester route.

There is also a broader philosophical issue. Historically, in transport, commercial victory has been to the swiftest – at least until the laws of physics combine to make the costs of going faster exceed the commercial benefits.

When I joined the railway industry, sections of the ECML had just been upgraded to 100mile/h, with the unprecedented performance of the Deltics giving a London-Edinburgh headline time of 6 hours. With Eastern Region's engineers dedicated to continuous improvement long before keizen, London-Edinburgh was down to 5hr when IC125 arrived and lopped another 30min off. Electrification and IC225 posted a sub 4h timing (by 1 min) which has now eased back to 4.08.

Since privatisation, of the inter-city operators, only Virgin on the West Coast has gone faster. And in terms of the ‘vitesse commerciale', all that has achieved is near parity with the East Coast.

Otherwise, a consensus appears to have emerged that journey times are less important than reliability. With the PPM, operators are incentivised to remain well within their comfort zone.

So can I leave readers with a question? Is the need for speed an old railway habit which the disciplines of privatisation have, thankfully, discarded, or is it the eternal commercial imperative which the industry abandons at its future peril?

This, of course, goes far beyond the WCML. For example, when will Route Utilisation Studies look at journey times as well as capacity. Our Forum columns await.

Continues.........