Electrification of the Great Western Main Line is the biggest upgrade to the line since it was built over 175 years ago. Running from London Paddington to the South West of England and South Wales, this line modernisation programme is providing more frequent services, thousands more passenger seats, and quicker journeys. Achieving these improvements has required comprehensive renewal of associated infrastructure as well as electrification of the line itself.

Arup’s contribution to the Great Western Main Line electrification programme has been significant, including the design of the overhead line, foundations and major enabling works for several sections of the route. Alongside the electrification works, the UK Department for Transport commissioned rail consortium Agility Trains to develop the Intercity Express Programme to replace an ageing fleet of inter-city trains. 

New bi-mode electric and diesel trains now run on the improved line, served by three new train care depots. Our planners, engineers and specialists delivered the design of these maintenance and repair facilities, which keep the new fleet of Class 800 Intercity Express trains manufactured by Hitachi Rail Europe in good running order. The depots were constructed by VolkerFitzpatrick with Arup as lead designer. 

Strategic upgrades to train care facilities

The Great Western Main Line’s new train care facilities have been built on brownfield and former rail sites at Acton in West London, Stoke Gifford near Bristol, and in Swansea. In all cases, the chosen sites posed a series of design challenges, including complex rail connections, limited highway access, geotechnical and geo-environmental assessment for major earth works and management of potential ground contamination, together with a range of flood risks. 

The Stoke Gifford facility near Bristol in South West England had previously been used as a waste landfill and waste reprocessing facility and required significant remediation. It is positioned within the existing Filton Triangle rail junction. Arup’s work on this depot included site-wide civil engineering as well as permanent way and line-side civil engineering, design of overhead line electrification and signalling. Our team led geotechnical investigations, provision of planning services and completion of a CEEQUAL sustainability assessment, resulting in an Excellent award. 

A similar range of services was provided for the Acton project in West London, where a new facility was created on the site of a former Eurostar train depot. Despite its previous rail use, the site required substantial refurbishment and reconfiguration. In Swansea, our scope of services was more extensive, including architecture and multidisciplinary building engineering for an entirely new facility located on the site of the former Maliphant rail sidings.

Design integration across a diverse supply chain

Successful completion of these complex rail depot projects demanded sustained collaboration across the project team, ensuring that design and construction issues were discussed and agreed prior to work starting on site. Our lead engineer role involved not only the production of civil and rail engineering solutions, but a detailed understanding of the specialist equipment and facilities that make up a state-of-the-art train care facility. One example of this complexity is the design of train servicing spines - approximately 250m lengths of concrete track slab, complete with effluent, water and fuel pumping facilities as well as electrical ‘shore supplies’, automatic sand transportation and delivery, lighting and drainage. These spines also incorporate pollution prevention systems and significant noise attenuation barriers. 

To complete integrated designs for each site, Arup had to meet the needs of a complex supply chain of specialist equipment providers. All three sites also have intricate track, OLE and signalling connections to the network, which are critical to the facilities’ operations. To manage these challenges, we employed our knowledge and ability to work within an operational railway. In addition, we applied and developed the latest technological advances in building information modelling (BIM), to the point where now we conduct fully immersive design reviews in virtual reality.

The team that Arup deployed on the Great Western trio of projects provided us with a first-class level of service.  We are now in a BS 11000 Collaborative Business Relationship with Arup, enabling us to work together to deliver better outcomes for us and our clients.

Paul Rayner

Project Director, VolkerFitzpatrick

Reuse of assets to reduce costs

The Eurostar North Pole depot in Acton was closed when Eurostar relocated to Temple Mills in 2007. Since then its use had been limited by insufficient train care facilities and a lack of direct connection to the Great Western Main Line. With a brief to reuse and adapt existing infrastructure wherever possible, we created a new connection from the depot to the mainline. We were able to produce a design that made almost complete reuse of track, overhead electrification and the site’s existing buildings,  reducing construction costs and completing to a tight delivery programme, enabling early train testing to commence in 2015.

Complex enabling works

Train care facilities are usually built in long thin strips to reduce the number of ‘shunting’ moves required as trains enter, exit and move around the facility. Unfortunately, the Stoke Gifford facility had to be created from a triangular site.

Despite the difficulties of the Stoke Gifford site, which had restricted access and had previously been used as a tip, the brief - to create a modern, high-specification, fully-equipped train maintenance and service facility, capable of meeting the rigorous operational demands of the Intercity Express Programme - has been met in full. Arup has worked collaboratively and proactively with client, operator and end-user teams to optimise the facility and meet all parties’ requirements.

Martin Garrett

Chief Executive Officer, Agility Trains West Ltd

Developing a design that would work for the fleet involved significant enabling works to move eight-metre-high earth bunds and the replacement of a collapsed culvert ten metres beneath the site. All material was retained on site, which resulted in the creation of a series of landscaped bunds, while installation of a new culvert was achieved using in-situ sheet pile shuttering – an early proposal from Arup as a way of eliminating the need for full open-cut options. This approach significantly reduced the Stoke Gifford site programme and overall cost. The result is an effective new culvert that lies up to 25m below the finished site level, retaining flood water and significantly reducing flood risk to properties upstream.

Arup has played a key role in the modernisation of the Great Western Mail Line. Find out more about our work that continues to shape the future of rail around the world.