Exploring Arup’s role in London’s new suburban metro system

When Crossrail, now known as the Elizabeth line, commenced operation in May 2022, it represented the culmination of more than three decades of endeavour, collaboration and tenacity. Millions of passengers annually benefit from the new system, which connects areas to the west and east of the capital, expanding capacity on London’s busy rail network by 10%, with a fast and regular service.

Arup played a key role from the very start, working in joint venture with our partners on infrastructure, tunnelling, geotechnics, station technical design, fire engineering, acoustics and many other elements.

Every multi-decade rail project requires a compelling vision and Arup has been championing public transport schemes, such as Crossrail, from the early days. In the late 1980s we were asked by the UK government to evaluate transport options for East London. Presented in 1989, our advice recommended more investment in rail infrastructure would ultimately be needed to address the city’s capacity and connectivity issues.

The Elizabeth line offers many valuable lessons for other major metro projects around the world, from design choices to tunnelling techniques and environmental, economic and social opportunities. The project also supports our belief that rail is transformative for communities, cities and nations, connecting populations to new opportunities for work, education and leisure.

The case for rail

During development the scheme provided years of economic stimulus to areas like Thamesmead, Woolwich and Abbey Wood, and by offering radically faster access to the city it has connected. Thousands of new homes have also been built within one kilometre of Elizabeth line stations, with populations growing and employment opportunities increasing within 500 metres of Elizabeth line stations in some of the city’s most deprived areas.  

Tunnelling and engineering feats

We assembled a team of 200 engineers and specialists to undertake extensive settlement analysis and damage assessments, to evaluate the impact of ground movement under the central tunnelled section. This involved the assessment and mitigation of over 4,000 buildings, railway, major utilities, and other infrastructure adjacent to the route to establish how it would respond to the tunnelling and station excavation.

Arup–Atkins then designed the 42km, 7.1m external diameter bored tunnels that would run under central London. Our team had to navigate the tunnels through London’s congested subterranean world, weaving them around building foundations, London Underground tunnels and a host of other structures and utilities.

At Tottenham Court Road the team had to thread the tunnels over the Northern line and below the escalators for the London Underground station with only 700mm between the Elizabeth line and Northern line tunnels.

Find out more about our tunnelling work

Managing noise and vibration

A new underground rail system potentially presents serious acoustic implications for those adjacent to or above its route.

We used prediction models to identify which buildings may be affected when the 200m long trains pass underneath them. Using this data, the team optimised the design of the tracks inside the tunnels to reduce the amount of vibration transmitted into the ground and hence minimise the impact of ground-borne noise from the railway.

Under two highly sensitive parts of the route – Barbican Concert Hall and Soho, home of many of the UK’s top recording studios – the solution was to float the entire track structure on springs.

Arup structural engineers designed this special floating track slab system, to provide a high level of vibration reduction without compromising the safe operation of the railway.  

Stations and above ground developments

We worked on technical design at six of the ten new central stations on the Elizabeth line, and helped shaped over-site development for commercial developer partners.

A new or developed station offers considerable opportunities to meet local needs. From developing new acoustically isolated above-station residential homes and offices in Soho, to shaping an enhanced passenger experience at Tottenham Court Road station, we took a flexible, creative and pragmatic approach to station design and over-site rail development.

Find out more about our station design work

Getting ready for day one

After construction concludes, a new railway line must prepare for day-to-day operations. This is a complex and detailed task, involving training, scenario planning and trials involving employees and the public. We have developed our own methodology for this ‘operational readiness and transition’ (ORAT) phase, and have successfully used it on the launch of many major infrastructure and transport projects. Learn more about how we helped launch the Elizabeth Line.

Find out more about how our ORAT service supported Crossrail's big day

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