Toolbox of solutions required to electrify UK rail

Speaking at the NCE's Future of Rail conference, Network Rail head of engineering and asset management Dave Hewings told delegates that a raft of solutions were needed to overcome the unique challenges facing UK electrification.

The UK has some of the smallest structure and railway gauges in existence, with Victorian assets in the Historical Railways Estate in danger of practices including infilling. Adjusting and reconstruction can put major delays into a project, although Hewings said that Network Rail was working on innovative new solutions to increase clearances and avoiding changing structures. The civil engineering world has been in uproar at changes to Great Musgrave bridge and potential threats to the 162-year-old Brunel bridge in Cornwall.

Toolbox of solutions

Hewings proposed a 'toolbox of solutions' including controlling voltages, the use of sewage arresters and using new coatings for better insulation solutions. He acknowledged that the issues required innovative solutions to try and 'take some of the pain out'.

Another potential solution is the use of bridge lifting technology to assist the electrification roll-out across the UK. The use of technological solutions has long been proposed in response to plans to infill or demolish parts of the Victorian railway heritage. In 2018, civil engineers intervened in the proposed demolition of a grade II listed masonry arch bridge which was causing problems for Great Western Main Line electrification.

Network Rail lost their application to demolish the Steventon bridge, while ElevArch, a subsidiary of French engineer Freyssinet in collaboration with Bill Harvey Associates carried out a successful trial to elevate a 160 year-old single span, 220t masonry arch bridge by 900mm using a series of 50t jacks.

A sustainable future

While Network Rail wrestles with the railway's historic legacy, HS2 is driving on with a series of innovations to build the infrastructure of the future.

The new Wendover Dean Viaduct in Buckinghamshire will be the first to feature the double composite approach. This involves sandwiching two steel girders between two layers of reinforced concrete to create a tough and lightweight span. The viaduct, which was recently granted planning permission by Buckinghamshire Council, will be the first of a series of proposed viaducts along the route to use this innovative construction method.

Designed by the main work's contractor, a team composed of Eiffage, Kier, Ferrovial and BAM Nuttall with design partner ASC and Moxon, this is one of 50 bridges proposed for phase one of HS2 between the West Midlands and London.

The slender design of the new viaduct will reduce its visual impact, while reducing the use of steel and cement cuts its environmental footprint. The nine evenly spaced pillars of the viaduct will also reflect the symmetry of the surrounding landscape.

The appearance of the thin concrete band against the rust coloured weathered steel beams will give the entire structure a lighter look and improved aesthetic appeal.

Reconstructing nature

Once the project is completed, the historic hedgerows will be replanted so residents and farmers retain maximum access to the countryside. Trees and shrubs native to the Chiltern chalk hills including Oak, Wild Cherry, Hazel and Beech will recreate the original woodland.

Inspired by an innovative design in France, EKFB has refined and improved the original in the context of the Chilterns. Technical director Janice McKenna said the design was always created with people and legacy in mind, and the carbon savings make it a project to be proud of.