Great Western Electrification Programme 2014-2019

Project value:
Project Commenced:
June 2014
Project completed:
December 2019
UK Power Networks (as part of AUC – a UKPN and ABB joint venture) & Network Rail

About the project

Enable Infrastructure (formerly BCM Construction) were contracted to deliver civils and electricals work over several years for the multi-billion-pound Great Western Electrification Programme (GWEP) and Great Western Route Modernisation (GWRM). 

The locations of our work extended more than 100 miles from Reading (Network Rail route section 2) to Cardiff (NR route section 9). Our work began with civils installation at Reading Auto Transformer Feeder Station (ATFS) in 2014 and then continued through the route sections into Wales.  

We provided Network Rail (NR) and UK Power Networks (UKPN) with design, full project management and implementation in both civils and electrical construction.  

One notable feature was our delivery of Network Rail’s – and the UK’s – longest HV independent feeder, extending from Royal Wootton Bassett in Wiltshire to Thingley Junction. This was a Detailed Design & Build, while we also delivered a Detailed Design (only) for the St Brides feeder, running from near Newport to Canton in Cardiff. In monetary terms, this was the biggest single part of the whole project, with a contract value of £8m. This scheme ran from September 2015 to April 2018.  

Another large element, at £2m, was the ‘HV Feeder and ATF (Auto Track Feeders) Cable/ Route Installation’ scheme, which covered multiple locations in England and Wales and ran from October 2018 to April 2019. 

Enable Infrastructure’s civils work to extend the existing Network Rail training school to create a new electrification training centre at Cocklebury Sidings in Swindon was one of the more unusual elements of our project, not least because we had to take care not to disrupt the training sessions that were going on there while we worked.  

Throughout the whole five-and-a-half years, Enable Infrastructure collaborated closely with NR and UKPN, thus ensuring continuity of work streams across this high-profile project. 

Another major factor in achieving this continuity was the involvement of colleagues from across the Enable Group, including not only the civils and Enable Power Systems teams from within Enable Infrastructure, but also the team from Enable Design (formerly Equate Design). This cross-group collaboration brings a unique contribution to the marketplace, which means Enable Infrastructure can tailor services to meet the client’s individual needs on every occasion.   

The challenge

Locations mostly a combination of brownfield sites (including old, disused rail sidings) and sites of special scientific interest (SSSI), with minimal site survey information at tender stage: both the ground and site conditions to a certain extent unknown. 

Enable Infrastructure sought to undertake detailed geotechnical surveys to provide the appropriate information to their design team for the works at each applicable site location. We also undertook meticulous superstructure surveys of several existing buildings that were due to be removed to accommodate the new substations; in doing so, we located some asbestos, which was removed through our supply chain. We engaged with Natural England and Natural Resources Wales when excavating/storing materials in a SSSI area.    

Logistical challenge presented by the long distances between sites (some of them more than 100 miles apart) that were constructed concurrently to a tight timescale. Also, access and egress restrictions on many sites.  

Enable Infrastructure devised a system of strategic geographical hubs to effectively manage logistics. These hubs also allowed for effective quality control of materials, with each delivery be inspected and then, on approval, allocated to an appropriate holding zone in readiness for future delivery to site. 

Third-party interface required with others on site, including, for example, National Grid and other contractors.  

Weekly interface meetings and dilapidation surveys were conducted to prevent congestion on site and reduce any stand-down time whilst carrying out construction or electrical tasks.


Haulage: issues, including training, regarding the cable train from Hoo Junction in Kent to Royal Wootton Bassett in Wiltshire. 

Continuous planning meetings and sign-off with IP Southern Route Access, along with migrating a plan in TVA and Western. Training commenced at least two weeks before the cable train and was compliant for this specific use. Collaborative working with NR on training and making sure attendance/approval of the quality received was signed off before any operation was granted a permit.  

Train operating companies (TOC) interface at Chippenham Station whilst carrying out the excavation of the buried route over 200m through the platform. 

Weekly meetings with Wiltshire Council, Great Western Railway and NR to agree a plan of working days and times. Complete exclusion zones around all excavated trenches and monitoring of any general public in the vicinity.  

Presence of at least five third-party contractors working along the main line on other elements of GWEP, such as overhead line equipment (OLE) stanchions, cables and piling.  Opportunities for securing full access under the rules of the route extremely limited. 

Collaborative working, including setting up base in the offices of third-party contractors/NR to enable access rights for cable management systems and associated cables throughout this route. 


Delay in the submission of approved for construction (AFC) drawings up to mobilisation date by the client. 

Close interface with the client’s engineering team and attendance at interdisciplinary review (IDR) meetings. Review of all A01s against the C01 drawings, alongside the client detailing any changes. 

Third-party contractor on site at Severn Tunnel Junction built their laydown area for the Welsh region overhead stanchions, affecting where the proposed route was to go. 

Re-programme tasks around third-party contractor works, hold weekly interface meetings, utilise other sites to commence works and bring forward.  


Existing Network Rail training school in service whilst extension works carried out. 

Traffic management plan put in place and watchmen on standby to mitigate any risk from overhead lifting. Interface meetings with NR held each morning to present the plan of works so that training sessions and visitors were not affected.   

The deliverables

  • Surveys, temporary designs, site set-up, vegetation works excavation and groundworks 
  • Concrete base installation, including large-scale formwork, driven piles and reinforcement retaining wall installation for the ATX/AEE/SMOS/Busbar Equipment; steel bottom piles for fencing 
  • Installation of troughing in and around substation compounds 
  • Under road and under track crossing installations (URX/UTX) 
  • Installation of temporary and permanent access road 
  • Access bridge installation 
  • Traffic management 
  • Security supply 
  • Palisade fencing/razor wire installation 
  • Installation of associated lighting columns 
  • Access steps/handrails 
  • Distribution Network Operator (DNO) route civils construction 
  • Earthing installation, including rods and mats 
  • Piling/crane mat design and installation 
  • National Grid substation excavation and ground material installation   
  • Cable pull/installation 
  • Jointing/sheath-testing/terminations/pressure-testing 
  • ITPs 
  • Handback documentation 

Locations: general 

  • Reading ATFS National Grid – civils and electrical 
  • Foxhall ATFS National Grid (Didcot) – civils and electrical 
  • Radley, Oxford, auto transformer station (ATS) – civils 
  • Royal Wootton Bassett ATFS – electrical  
  • Thingley Junction ATFS National Grid – electrical  
  • Hullavington ATS – civils  
  • Dr Day’s Junction, Bristol NR depot sectioning auto transformer site (SATS) – civils  
  • Westerleigh Junction mid-point auto transformer site (MPATS) – civils and electrical 
  • Filton, Bristol MPATS – civils  
  • St Brides ATFS (Newport) National Grid – civils and electrical  


  • Detailed Design Form 1/2/3 civils and electrical – Western and Welsh Feeder 
  • Trough-Tec Systems (TTS) trough/C19 concrete installation 20km 
  • Eight URX/UTX installations 
  • Station platform buried route installation 200m 
  • Raised glass-reinforced plastic (GRP) route 2000m, using ARCO/Castioni 
  • 630mm2 XLPE cable pull installation using IP Southern Cable Train/Road Rail Vehicles (RRVs)/ mechanical winches = 46km 
  • Neutral return cable installation = 11,000m  
  • Spider plates installation 
  • Sheath voltage limiters installation 
  • Inline jointing installation 
  • Shield break jointing installation
  • Sheath testing on cable 
  • Terminations 
  • Final pressure test 
  • ITPs 
  • O&M files and H&S File 
  • Handback formalities  

Locations: HV independent feeder design & installation 

  • Royal Wootton Bassett to Thingley Junction – Detailed Design and Build  
  • St Brides to Londyke and Canton – Detailed Design Only


  • Site mobilisation, welfare set-up, including clearance of sites 
  • Installation of TTS Polymer troughing/C19 concrete 
  • Installation of raised GRP Schneider trough route 
  • Transitions between stagnation and TTS and elevated GRP 
  • Construction installation of ten UTX/URXs 
  • 400m2 XLPE cable pull via RRV/mechanical winch off track/hand pull
  • OTX cable installation with MEWPS.
  • ARMCO barrier protection installation 
  • Cable jointing 
  • Sheath testing 
  • Terminations 
  • Pressure testing 
  • ITPs 
  • Handback documentation 

Locations: HV feeder and auto track feeders (ATF) cable / route installation 

  • Cocklebury Feeder 
  • Canton ATF 
  • Maindee ATF 
  • Pilning ATF 
  • Severn Tunnel Junction ATF 
  • St Brides ATF


  • Site clearance, including vegetation 
  • Installation of ARMCO barriers 
  • Excavation of foundation pit, prepare base in situ concrete pad stones, including formwork 
  • Reprofiling of berm 
  • Tarmac installation 
  • Cable trenches and connected cable installation 
  • Air conditioning unit foundations and installation 
  • Foul drainage 
  • Landing of Elliott’s cabins 
  • ITPs 
  • Handback documentation 

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