Reopening the Great Central isn’t an alternative to building High Speed 2
The abandonment of the Great Central Main Line meant destroying a nationally strategic piece of infrastructure, but that doesn’t mean reopening it will solve today’s railway challenges. GARETH DENNIS explains why.
A version of this article also appeared in Issue 898 (12 February 2020) of RAIL magazine.
Throughout the last ten years, as plans for High Speed 2 (the new dedicated passenger line connecting London, Leeds and Manchester via Birmingham) have become clearer and the route more refined, calls for its cancellation have become more frenetic.
I spend a lot of time tackling these demands and the barrage of misinformation that accompanies them. The suggestion that “reopening the Great Central Railway” is a viable alternative to HS2 is a common one, based on a variety of mistruths and misunderstandings.
The claim isn’t confined to railway forums or Twitter, either… Several publications have made the same assertion, most recently including the Spectator: Ross Clark penned his piece “There is a far better option than HS2” in August, and it makes all of the same false arguments.
There are two core misunderstandings that lead people to the conclusion that the Great Central Main Line provides any sort of solution. One of them is a lack of awareness of what HS2 achieves; the other is the idea that GCML has a “high-speed” alignment, which hasn’t been true for a long time.
Originally, the bit of railway we’re all talking about was called “the London Extension of the Manchester, Sheffield and Lincolnshire Railway” though it was quickly/thankfully renamed as the Great Central. It ran from Marylebone to Sheffield and was built between 1894 and 1899 at a time when 80mph was the fastest services ever really got.
Whether you think City of Truro reached the tonne in 1904 or Flying Scotsman did it 30 years later, these were exceptions to the rule and “high speed” in the 1890s meant travelling between 70–90mph. To enable these speeds, the extension was built with minimum radii of one mile (other than on station approaches) to allow the fastest running that could be foreseen at the time.
That’s 1609.344m in new money — whilst flat for the time, it’s pretty curvy for today’s railway.
In RAIL886 I looked at speeds, curvature and applied cant… As a permanent way engineer, these are the calculations I use day-to-day when designing new or modified railway alignments.
Without cant, the fastest a train can traverse a mile-radius curve on jointed track is 65mph (1). By lifting the outer rail above the inner rail through the curve, we apply cant and balance curving forces allowing speeds to increase. The maximum allowable cant for jointed track is 90mm, and the speed can therefore increase to 95mph (2).
Using modern track materials (e.g. continuous welded rails and pre-stressed concrete sleepers) allows an increase in the maximum allowable applied cant to 150mm but that doesn’t allow a huge leap in running speed — if you reinstated the GCML today you could squeeze no more than 115mph (3) out of it — hardly “high speed”!
To get 125mph with the maximum applied cant allowed for modern materials, a minimum radius of just over 1850m is required (4). Thus the GCML alignment is too tightly curved for 125mph running.
Modern high-speed lines require much more shallow curves than the GCML provides, even with the maximum applied cant (5). To achieve HS2’s 225mph top speed, the tightest curve you’ll see has a radius of 6250m (6)… Reduce the amount of applied cant (as is preferable for a new railway line) and the required radius increases even more.
But how do these calcs stack up against the actual operating speeds on the GCML?
I had a dig around for some timings… On the straight sections around Calvert the passenger expresses were often recorded at speeds of 80–90mph, and occasionally higher (all I can say is: crikey). It’s worth noting that this is the section of the GCML that HS2 will reuse anyway… And the steam expresses of the time made the most of the lack of curves!
90mph was nippy before the 1950s, but the Class 158 Express Sprinters are running around at that speed today and nobody can attempt to convince me those are high speed trains.
In any case, I feel like I can have reasonable confidence in my assertions on what speeds can be achieved on the GCML, as the last time anyone did any alignment design for construction on the route was to close the gap between the two Great Central heritage lines at Loughborough, and the person who did it was me!
The Great Central Main Line should never have closed… Its demolition was one of the worst single acts of state-sanctioned vandalism in the UK’s history and we will rue the day that we built stuff on the trackbed. But it was never a high speed railway.
Anyway — back to High Speed 2.
As I’ve described before (see RAIL858), HS2’s main benefit is actually not on HS2 at all — it is on the existing network where the new capacity will be felt, as more local, commuter, regional and freight services are able to operate once the non-stop trains are eliminated.
On opening, Phase 1 of the new line (from an expanded Euston to the new station at Curzon Street in Birmingham) will relieve the West Cost Main Line south of Birmingham. Phase 2A — which is looking increasingly like it will be incorporated into Phase 1’s delivery timeline — will further relieve the WCML northwards to Crewe.
Only when it is fully opened up to Manchester and Leeds will HS2’s full potential be unlocked, resulting in a huge freeing up space on all of the major north-south main lines and resulting in a doubling or even tripling of capacity along commuter routes such as Doncaster to Leeds or Stoke to Manchester.
If the GCML realignment was to be reinstated, not only would this fail to provide a station at Birmingham or Leeds, but the reduced speed of the curvy alignment would also mean that the “new” line would only relieve the Midland Main Line between London and Sheffield. You’d have to build other lines to relieve the West Coast Main Line, East Coast Main Line, Cross Country route amongst others, which would take more time, require more engineers (at a time when these are in increasingly short supply) and would be substantially more environmentally damaging.
If you don’t believe me that HS2 takes the optimal alignment between Britain’s major cities, trust the Stephensons, whose designed network in 1841 matched HS2’s proposals exactly. Seriously — look it up!
High Speed 2 is actually the quickest, cheapest and least disruptive way to provide a step-change in capacity on our railway network, enabling modal shift for people and things away from Britain’s roads, allowing us to greatly reduce our GHG emissions, and giving us a chance to avoid climate catastrophe.
It is likely that HS2 will finally get the nod from Number 10 in January [Edit: It took until mid-February in the end]. Let’s get on and build it once and for all.
