Private fears in public places, part 2

(… continued from Private fears in public places, part 1, posted on 8 Jun 2017).

When, in 2002, Virgin Trains introduced the Class 390 “Pendolino” trains into service on the West Coast Main Line (WCML), the tilting technology allowed the general speed limit to be increased from 110mph to 125mph, thereby reducing journey times. In his Modern Railways article HS2’s Conventional Compatible Conundrum the magazine’s Industry and Technology Editor, Roger Ford, observes that at the completion of Phase 2a 70 per cent of HS2 services from Euston will still employ the legacy network “to reach Stafford, Liverpool, Manchester, Preston, Glasgow and other destinations”. If current thinking prevails, and HS2 conventional compatible very high speed trains (“CCVHSTs”) do not employ tilting technology, then sectors of HS2 journeys on the legacy network will be subject to the 110mph maximum and take longer than they do now, thereby offsetting some of the gains made from the sectors run on the new high-speed tracks. Mr Ford recalls that “back in 2012” it had been estimated by HS2 Ltd that “the absence of tilt would cost 11 minutes on London-Glasgow timings”.

However, as is true for many choices that we have to make in life, it is not quite that simple. The ability to tilt when negotiating curves adds weight and complexity to rolling stock, and HS2 Ltd has assumed that a CCVHST incorporating tilt technology would be limited to a maximum speed on the high-speed track of 300km/h rather than 360km/h expected if the capacity to tilt is not accommodated. So journeys on the high-speed sector would, in fact, take longer for tilting trains, offsetting gains to be made on the legacy network. To add to this there is a problem foreseen when, and if, captive high-speed trains are introduced onto HS2, in that running trains with different maximum speed capabilities on the same track can reduce capacity. This is because a faster train following a slower one will need to maintain the safe operating distance throughout its time on the high-speed track, necessitating either increasing the spacing between train paths, or leaving unused train paths to act as buffers; either way capacity is reduced.

HS2 Ltd has also advised that it is envisaged that a number of (unidentified) minor linespeed improvements will be made to the northern WCML, allowing non-tilting train journey times to be reduced; these improvements are not regarded by HS2 Ltd as bringing any journey time improvements for tilting trains. It also appears that no account has been taken of the possibility, through implementing in-cab signalling, of increasing the maximum linespeed for tilting trains to 140mph; an improvement that Virgin Trains has been lobbying for.

These appear to show that, on journeys north from Euston, there would be no overall journey time gains from employing tilting technology. It is clear that Mr Ford is sceptical about this evidence (see footnote 1), although he is not very expansive in explaining his reasons why.

With the travel time information that the Government has provided for a tilting train running at 300km/h on the HS2 track in mind, Mr Ford extends his analysis into a consideration of the advantages that might be gained by reducing the maximum operating speed for HS2 from 360km/h to 320km/h. He notes that when Phase 2a is operational the journey time estimate from Euston to Crewe is six minutes less at 360km/h (non-tilt) than 300km/h (tilt), and estimates that this difference would be about five minutes on that one-hour journey with a maximum operating speed of 320km/h.

Mr Ford gives the following examples from around the world where, despite having the capability to operate at 350km/h, railway administrations have chosen to run at 320km/h or lower speeds:

  • French Railways’ LGV Sud Europe Atlantique has a design speed of 350km/h, but trains will run at a maximum 320km/h
  • Despite trials demonstrating that it is technically feasible to operate the Hitachi ETR400 trains supplied for the Italian high-speed railway at up to 350km/h the services will be limited to a ceiling of 320km/h in service
  • Whilst trains on the Wuhan-Guangzhou route in China ran up to 350km/h when the service began, the maximum speed has subsequently been reduced to around 310km/h

Mr Ford quotes that France’s SNCF made their decision because operating at the higher speed “would raise fares sharply for a marginal gain in time, everything from maintenance to energy costs would have risen exponentially, which simply wasn’t worth it”.

(To be concluded …)

Footnote: He precedes this section of his article with the digression on Professor Frankfurt’s paper On Bullshit that I refer to in part 1, in order “to put what follows in context”.

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