Elizabeth Line tunnels under central London

Tunnel design

Tunnels provide the networks and connections that underpin much of our lives. From water, sewer, cables and utilities to high speed rail, metros, roads, mines, science projects and industry, they connect us with vital resources, services and each other.

Today, the underground environment we used to rely on to take congestion off our city streets is as busy and congested as life above ground. Arup designs complex tunnel schemes that navigate this underground world, aligning both climate and cost imperatives, and exploring ways to reduce the resources and materials used in construction.

Beyond the core tunnel disciplines of civil engineering, architecture, geotechnics, machinery and soil mechanics, our global team includes experts in ventilation, lighting, MEP, acoustics, fire, drainage, safety and public health. Our approach – ‘total tunnel design’ – integrates all the relevant disciplines leading to lower-risk and more efficient, effective and affordable designs. This approach makes projects more sustainable, reducing excavation and materials by effective space proofing and lining system optimisation and introducing innovations such as extracting heat from tunnel linings.

How we can help you

Ventilation

Controlling temperature, air quality and experience.

Ventilation

Ventilation systems can undermine the feasibility of tunnel projects.

Arup has provided tunnel ventilation in highly built-up areas such as New York’s Second Avenue Subway. We guide our clients to help solve highly complex technical challenges as well as using less intrusive equipment that can be used for multiple purposes.

We try to harness natural ventilation where possible, or – going beyond design codes – use sophisticated modelling to unlock efficient yet affordable designs.

Today’s ventilation systems need to be adaptable for a rapidly-changing transport environment. The mass use of electric vehicles is being mandated by many developed jurisdictions, leading to new considerations for tunnel ventilation and safety. Arup is helping clients prepare for the future.

Digital tools

Our team works with simpler 1D models or advanced Computational Fluid Dynamics 3D tools as well as our own agent-based modelling tool – Arup Mass Motion – to better understand both human behaviour and activity, as well as the physics of ventilation in tunnel environments during emergencies. These insights allow us to accurately plan for evacuation scenarios from a tunnel affected by fire smoke and identifying – for example - where people will be able to exit underneath smoke caused by fire.

Applying this data-driven, quantitative analysis of risk early on helps us establish a realistic, performance-based view of ventilation requirements even at concept design stage.

Influencing tunnelling standards

Tunnel vent design is rightly driven by safety standards that take account of both normal operations and rare eventualities such as fire. Simply following codes can impose the inclusion of huge systems, fans and vents that will rarely – if ever – be used. As co-authors on many of the global committees that publish tunnel ventilation standards, we understand the intent of these codes, and create lower-impact answers that deliver the required performance.