Return to Archive -by date - by topic.
Interfaces do not look after themselves – especially between track and train.
Early in March, the railway engineers struck back. In a joint letter to the Strategic Rail Authority and the Department for Transport's nascent Rail Directorate, the Chairmen of the six System Interface Committees (SIC), warned that the technical specification for the InterCity 125 replacement (HST2) must be established, in detail, before tenders are invited.
Ordering trains is addictive and my Austrian cousin Sigmund thinks that he can already detect symptoms of Old Railway Procurement Disorder in DfT Rail. Civil servants have caught the bug and there is talk of going out to tender for HST2 later this year.
So, over to the SIC Chairmen. They warned SRA/DfT that if they don't allow time for HST2 and its interfaces to be analysed and optimised, it will be a case of tender in haste – repent at leisure. If tendering is rushed, capital and whole life maintenance costs of HST2 could be up to 10% above those for an optimised design.
This is, of course, not what privatised traction and rolling stock procurement was supposed to be about. Manufacturers would supply standard trains, incorporating standard Euro-kit almost off-the-shelf. This is roughly what happened in the first round of procurement, with mixed results at the interfaces.
For example, some of the new generation EMUs are lardbutts which is bad news for the track and power supplies. Some manufacturers have used Eurobogies which require stiffer suspensions and are more prone to generating rolling contact fatigue. Somewhere along the line the interfaces between train and power supply was forgotten. And so on.
In the case of the Class 390 Pendolinos, the specifications for some interface were still being defined when manufacture was underway. And when it came to structure gauge the universal tendency was to err on the side of caution to maximise route availability and residual value rather than interior space.
This was the opposite of the policy applied to the original HST. For example, the (then) innovative disc brakes were employed to align the stopping distance from 125mile/h with existing sighting distances for 100mile/h trains. Despite the compliant suspension, giving that still unsurpassed ride, every effort was made to maximise the interior width – as the chamfered ends reveal.
An optimised train is best for the operator, the maintainer, the infrastructure owner and maintainer. And, as HST still shows, the passenger.
As readers of my Safety Report will know, after the Hatfield derailment, the Wheel Rail Interface System Authority (WRISA) was formed to bring together both sides of the contact patch in the battle against rolling contact fatigue. However, when professional indemnity insurance for the Authority's members proved to be unaffordable, WRISA and its sister TPWS System Authority were, scandalously, wound up.
But not all was lost. In place of Authorities there are now System Interface Committees. While they lack ‘authority', they are certainly not short of influence. According to Informed Sources, the letter about HST2 came as quite a shock to DFT/SRA.
Table 1 lists interfaces committees. It also shows some heavyweight engineering experience among the Chairmen.
SIC Abbreviation Chairman
Vehicle/track V/T Andrew Doherty. Director of Railway systems & Vehicle Engineering, Network Rail.
Vehicle/train control V/TC Clive Burrows. Director of Engineering, Rail, First Group
Vehicle/Communications V/Comm Allen Johnson Chief Operating Office EWS
Vehicle/structures V/S Andrew McNaughton Chief Engineer, Network Rail
Vehicle/Vehicle V/V Rebekah Sellick Director, Engineering, ATOC
Vehicle/Traction Supply V/TS Anthony Mercado. General Manager, Service Delivery WCML Alstom Transport.
How you manage the technical interfaces is commercially, as well as technically, important. For example, increasing vehicle length within the structure gauge offers the possibility of reducing construction cost and train weight.
When IC225 was being tendered by British Rail in the 1980s, one option proposed was to increase the length of the vehicles from the 23m of the Mk 3 IC125 coach to 26 metres. This would have meant fewer vehicles for the same capacity.
Alternatively, there is the option of articulation, TGV-style, which has its proponents. This, too, reduces train weight because of fewer bogies and can allow a wider vehicle. And when a Eurostar swishes through my local station it sounds a lot more track friendly than an IC225.
How long would it take to optimise HST2? Informed Sources reckon a year to 15 months. This would be no bad thing, since it would allow more time to thrash, sorry, evaluate potential diesel engines.
Given the real world experience represented by the chairmen and their committees, you might have expected SRA to welcome this thoughtful intervention. But no.
According to Informed Sources, the Chairmen were told that, with HST2 procurement already at an advanced stage, revisiting the technical specification would introduce unnecessary delay. Nor was there any response to the concerns expressed in the original letter. The SIC chairmen were simply urged to get behind the SRA procurement initiative.
This is both surprising and not unexpected. Announcing the pre-qualifiers for the Greater Western Franchise SRA said ‘t he SRA and the Government are currently in close discussion with operating companies, Network Rail, manufacturers and others to establish a collaborative project aimed at procuring the next generation of High Speed Trains. We think this is best done as a single industry project. For this reason we will not be inviting or accepting any separate proposals for HST replacement from the bidders for the Greater Western Franchise'.
Clearly HST2 has ministerial momentum, not many civil servants would be brave enough to delay it for technical reasons. But equally, the 400lb gorilla that is Network Rail is not going to let kit onto its infrastructure that does nasty things across the interfaces.
Mention has already been made in this column about the direct current power supply issues around the CTRL Domestic Stock, where Hitachi is the preferred bidder. My chums at SRA say all will become clear shortly, when I will see the error of my ways.
Hmm. The SRA's power modeling specification issued in January certainly assumed 3,400A for a six car unit, compared with the standard 4,500A for 12 car Electrostars, the performance of which the new trains has to match. Hitachi reckon their heavier train can equal a Class 375's performance drawing about 4,600A, but the power supply modeling computers are not so sure.
More apposite to the SIC Chairmen's letter is the issue of bogie stiffness, which clearly affects the track. Two of the SIC Chairmen, Messrs Doherty and Burrows, have been doing a lot of work on this for the Siemens Class 185 diesel multiple units. Work was certainly needed because the Desiro electric multiple units are noted track crunchers and munchers.
Not surprisingly, meeting these same desiderata has caused some headaches for Hitachi because of the wide speed range of the Domestic Stock. The problem is what dynamicists call yaw/stability conflict.
For a bogie to remain stable when running at high speed, it needs to be stiff in the yaw axis. But for good curving bogies have to move easily in yaw so that they can adopt a radial attitude on curves.
Thus, blitzing down CTRL you need a bogie that is stiff in yaw, bimbling round Kent it needs to be soft. This is not, of course, a new problem.
When HST started running over 30 years ago, the power car bogies had a tendency to hunt at speed. The Chief Mechanical & Electrical Engineer took the problem to BR Research at Derby, then was at the cutting edge of dynamics, which and came up with the solution – the yaw relaxation damper.
This involved controlling the bogie with a damper which was stiff at high frequency – that is at high speed, but soft at low frequencies, for example when entering a curve. Problem solved.
Thirty years on and Hitachi face the same problem, but with bogie stiffness parameters influenced by the post Hatfield awareness of rolling contact fatigue. According to Informed Sources, the SRA team handling CTRL-DS procurement were inclined to take a sympathetic line on meeting the bogie stiffness spec', until Network Rail pointed out that if you wanted to run on their infrastructure compliance was mandatory not optional.
So when the election is over, and ministerial egos have moved on, and Dr Mike Mitchell is in charge of DfT Rail, look for some more chest beating from the Melton Street gorilla and the six horsemen of the interfaces.
Return to Archive -by date - by topic.