The development of HS2 was exemplary
01 Mar, 2024 By William Barter
As a one-time railway operator, I’ve sometimes pondered on which sort of engineer is the operator’s best friend. Probably it depends on what sort of railway you are operating.
On a rural or freight railway, it’s the permanent way engineer, as you cover up each other’s mistakes. On a suburban railway, it’s the signal engineer who provides capacity, keeping trains moving when all is well, not just stopping them when it isn’t. On an InterCity railway, it’s the rolling stock engineer, who puts into service each morning trains that will earn hundreds of thousands of pounds during the day.
How about a high-speed railway like High Speed 2 (HS2)? You all matter! It’s a system, and every part is critical to delivering the whole.
Even sorts of engineer I’d never heard of matter – who would think that the tunnel ventilation engineer is critical to keeping headway down and thus capacity up through the tunnels approaching Old Oak Common? But dissipating waste heat from trains braking matters just as much keeping speed up over turnouts or maintaining a flow of trains through the platforms.
So, development of a major rail project, especially high speed, is a constant process of iteration and compromise, not just with the engineering disciplines, but also with the economists building the business case and forecasting demand impacts of each compromise.
Now that HS2 has become everyone’s whipping boy, perhaps I can set down that development of HS2 was exemplary in the iteration between the train service specification, the timetable planning and the engineering.
In fact, it is the best I have ever known in a 50-year career.
The operational plan – essentially the timetable – links the engineering and the demand, but considering how many specialists are employed on those, it is ironic that for several years the emerging timetable for HS2 train services was in the hands of one man and a dog (I am not joking – every time I hit a problem I took Quintus for a walk and the answer would hit me half way round).
Back in 2012, a train service specification was very clearly set out for the 10 trains per hour of Phase 1.
Parts of it look odd now, such as a combined Liverpool and Birmingham train splitting at Birmingham Interchange. Timetabling quickly showed that having one Birmingham train out of three doing something so off-pattern would be highly disruptive to platforming at the termini (our current rail minister Huw Merriman might ponder this when dreaming of Liverpool and Manchester portions splitting at Crewe) and the idea vanished very quickly.
There were odd gaps in the specification, such as absence of calls at Lancaster, Carlisle and Stoke-on-Trent.
The first of these was solved when timetabling showed that Phase 2A journey times would allow what Phase 1 would not, namely extension of the proposed Preston terminating train to Lancaster, whilst a ministerial decision dealt with the latter two issues in the context of Phase 2A.
For Carlisle, work by Network Rail showed that there was capacity to run the Phase 2B Glasgow and Edinburgh portions separately from Carlisle instead of being forced to run combined to Carstairs, implying a stop at Carlisle that was then reverse engineered into the Phase 2A specification.
For Stoke, a service to Euston from Macclesfield, serving Stoke and Stafford before joining the high-speed line was built into the Phase 2A specification, using a path freed by running a Liverpool and Lancaster train combined to Crewe.
Ironically, the big winner from this was Liverpool, whose two trains per hour could then both run direct via Phase 2A, instead of one having to run via Stafford and thus present an uneven service interval at one end or the other.
As to the relationship with engineering, an effective track layout for Euston was developed simply by two people talking to each other. The lack of options, sifts and appraisals might horrify some, but it worked.
At Old Oak Common, similar common sense saw the layout specified to keep the highest possible speed for trains into those platforms most likely to be used for Euston trains, thus keeping down the headway peaks that arose from trains slowing for the stop. This, amongst other reasons, is why Old Oak does not work well for the terminating trains that it was not intended for. Resilience was built in, to the extent that any one turnout could fail either Normal or Reverse and a normal train service still be operated.
A similar approach to turnout speeds and configuration at Manchester Airport even led to the operationally ideal solution being the cheapest, which is almost unheard of, whilst the delightfully flexible layout for Curzon Street was developed only a little more formally.
Sometimes, though, it seemed as if the more formal the process, the worse the outcome!
An early fixation on connecting HS2 into the slow lines at Crewe stemmed from an appraisal process seemingly designed to get the wrong answer for the right reasons, combined with an over-literal interpretation of requirements that were simply intended to ensure that HS2 trains could access a station platform.
But as a system, the combination of Phase 1 and Phase 2A would have worked very well as a railway, for instance with turnround times that would have been adequate without being excessive, thus using the fleet economically, and ‘parallel moves’ falling at critical junctions such as Crewe North.
Phase 1 by itself (in other words what we have now reverted to) really didn’t work well. This is why we invented Phase 2A, and the Public Accounts Committee quite rightly says that the government has no idea how the truncated system will work operationally (they probably didn’t even realise it was an issue).
And of course, if you spend a decade developing a scheme then change it overnight, the change is not likely to be for the better. All the weaknesses I see in the HS2 system were introduced during the petitioning process.
Green tunnels, assumed to form a single block section so as to respect a ‘one train at a time’ rule, extend headways, but maybe some equivalent to Southern Region tunnel controls might be considered, giving a second train a movement authority into the tunnel so long as the first has a movement authority to leave it.
Extending the Chilterns tunnel in response to petitions introduced new headway peaks due to an extended ‘one train’ section combined with a long steep gradient; it would probably have been better to go a little further so as to reduce the gradient and to justify another proper ventilation shaft.
The worst outcomes of all though can be expected if you let think-tanks, Special Advisers and property developers specify and design your railway. But that is inconceivable – isn’t it?
William Barter is an independent rail consultant who consulted with HS2 Ltd on timetabling, capacity and operations costing