Earthing and Bonding Techniques and Challenges Case Study – Crossrail

Crossrail is building a new railway for London and the South East. It will be known as the Elizabeth line when it opens through central London in December 2018. The complete railway will run from Reading and Heathrow in the west, through 42km of new tunnels under London to Shenfield and Abbey Wood in the east. The project is building 10 new stations and upgrading 30 more, while integrating new and existing infrastructure. New state-of-the-art trains will carry an estimated 200 million passengers per year.

Crossrail has a vast amount of railway, mechanical, electrical public heath (MEP), depot equipment, and rolling stock systems. These systems must contribute to an economic, safe and suitable Crossrail Earthing and Bonding Network (CEBN). The project has undertaken an array of construction such as tunnels, surface/subsurface stations, intermediate shafts, portals, cross passages and bridges. This has brought about a considerable number of construction techniques, programme alignments, stages, such as energisation and contract delivery types which all contribute to the project complexity. Therefore the CEBN challenge was not only delivering a safe CEBN for the recognised systems but also the large civil elements which make up the majority of the project. The CEBN had to cover all scope which was new and unique in the UK, i.e. an underground metro style 25kV high capacity service. Crossrail is a new railway, built on new and existing assets and areas in a much built up urban environment in London. This includes an already operational complex AC/DC railway network. Figure 1 presents systems and structures which the CEBN had to cover.