Engineering HS2

We make no apologies for returning to the subject of HS2 which was cut back as it “no longer reflected post-lockdown changes in travel”. Yet, as Matt Atkins describes, recent ORR figures show a trend of increasing rail passenger numbers. The last quarter’s 21% increase brings journeys up to 90% of the pre-lockdown levels. Cancelling HS2 phase 2 is apparently not a problem as the Network North proposal claims to double West Coast Main Line capacity to 250,000 seats a day, yet the reality is that it now offers little benefit north of Birmingham.

It is not unreasonable to expect that the basis for figures used to justify major policy announcements should be made public, yet the Department for Transport (DfT) refuses to divulge how this HS2 capacity figure was derived. Readers can draw their own conclusions as to why this should be the case.

HS2’s former chief engineer, Andrew McNaughton once described HS2 as the work of generations. He was right to do so, though it will be more generations than he first thought. The problems that HS2 was to resolve have not gone away. Years of work developing HS2 produced a solution that is unlikely to be much different from that developed by others trying to solve the same problem. Though it will take decades, it is quite possible that the full HS2 Y network will eventually be built.

In the meantime, a huge amount of work is being done to construct HS2 phase 1. There are many reasons why this is an expensive railway. One is overheads and procurement arrangements from which lessons must be learnt. Parliament has also willed expensive environmental mitigation such as green tunnels which cost three times more than cuttings. HS2’s route requires costly engineering. Its 47km leaving London and 15km into Birmingham is almost all in tunnels or on viaducts, while its complex Delta Junction has 13 viaducts. High levels of construction inflation have also added £10 billion to HS2’s 2019 estimate.

In this issue we focus on the project’s impressive engineering and describe how innovative techniques are delivering cost reductions. This includes reusing millions of cubic metres of sometimes contaminated earthworks on site. We explain the bio-remediation of spoil from the derelict Washwood Heath site and how CL:AIRE and DIGGER enabled 26 million tonnes of spoil to be reused, avoiding the need for large numbers of HGV movements.

The caterpillar shape of the Victoria Road crossover box also reduced the excavations required. There were also cost savings from constructing viaducts with all major components manufactured off site for HS2 which is a UK first. Another first for HS2 is the double composite design of some of its viaducts whose benefits we describe. HS2’s 104km of tunnelling is a logistical exercise of feeding tunnel boring machines (TBMs) with concrete segments and removing their spoil. We describe the deployment of these machines to explain why the Northolt tunnels need four TBMs and how TBM Dorothy’s cutterhead is boring three tunnels.

HS2’s website has a legacy section with 200 papers describing the project’s innovations. A significant HS2 legacy is building a diverse, skilled, and talented workforce across its supply chain, of whom 4% are apprentices. Some of these engineers feature in website video clips where they, quite rightly, proudly explain the engineering for which they are responsible. Despite HS2’s curtailment, hopefully such engineers will be able to support the rail industry for years to come.

Inspiring future engineers is one of the aims of the National Railway Museum’s masterplan to increase visitor numbers. As we describe, the museum’s new Wonderlab and planned Railway Futures Gallery should encourage young people to engage and get excited by railway engineering.

Developing rail engineers by giving them a safe, practical on track experience is the aim of the Permanent Way Institution’s practical track challenge. As we report, this year 38 participants benefited from this worthwhile initiative which was held at the Bo’ness Heritage Railway in Scotland. The support of all the companies involved has to be acknowledged without whom this event would not have been possible.

Lessons from the collapsed wing wall at Yarnton are described by Mark Phillips who highlights key issues from the Rail Accident Investigation Branch’s report into this incident. These include the need to accurately measure bulges over time and improve structural defect risk scoring. Also at risk of collapse was an abandoned hotel which is closing the railway at Ayr for eight months. We describe why and suggest that there are lessons to be learnt to avoid this situation reoccurring elsewhere.

Birmingham New Street’s 1960s signalling equipment was becoming increasingly difficult to maintain and did not have the flexibility needed to reliably run 1,200 trains a day through its constrained infrastructure. Resignalling the station was done in seven phases over many years. In a comprehensive feature, Paul Darlington explains how the final seventh phase of this project was delivered and the benefits of its various innovations.

The innovations being developed to improve level crossing safety are explained in another feature. Although Britain’s level crossings are among the safest in Europe, there are many near misses and, sadly, occasional fatalities, particularly at footpath crossings. We explain how Network Rail’s report ‘Enhancing Level Crossing Safety 2019 to 29’ has a strategy to reduce this risk.

With ever greater connectivity, cyber threats present an increasing risk to railway systems. For example, trains were stopped in Poland after hackers accessed an open channel VHF radio. Clive Kessell’s feature shows that this is a complex topic. Yet its key messages are to maintain awareness of this threat and ensure basic precautions are taken.

Rail Engineer was present at the Siemens Mobility press conference in Chippenham when it announced a £100 million investment in new premises which are expected to open in 2026. This will ensure that the company’s skilled local workforce of 800 people will continue to serve the UK signalling market. At this event, Chancellor of the Exchequer Jeremy Hunt advised that the Government will back this plan as part of the UK’s manufacturing revival which will be encouraged by tax reliefs of up to 25%. Unfortunately, tax reliefs were not enough to save the thousands of jobs at Alstom’s Derby plant and its associated supply chain.

The risk to such plants was highlighted in a 2023 Railway Industry Association’s report which warned of the consequences of the hiatus of rolling stock orders. It also called for a long-term industry strategy to create a smoother train order profile. Yet, it is now almost three years since the Williams Shapps report committed to the production of such a strategy. Sadly, the Derby closure is an example of the consequences of the lack of a plan for Britain’s railways.

Lead image credit: HS2