Upgrading the West Coast Mainline’s (WCML) power supply at Bushey, Hertfordshire, has presented a long-standing challenge. Access to the line, where local commuter services run on slow lines alongside a busy section of the mainline, has been the principal challenge.
In spring 2026 Octavius successfully delivered an ambitious solution to the stubborn challenge at Bushey – working to an almost unprecedentedly compressed planning and delivery schedule.
Octavius began work on the Bushey power supply upgrade (PSU) in autumn 2025, under an Early Contractor Involvement (ECI) contract with Network Rail, issued through the North West and Central CP7 Enhancements Framework. When reassessing previous attempts to deliver the upgrade, and evaluating and new way forward, the team identified a rare event on the WCML: the opportunity of six day’s uninterrupted work.
It was determined, in late December, that Easter blockades either side meant the Bushey section was out of service during the April holiday. This opportunity, which included the DC lines being out of service for 100 hours, was too good to miss. With the absence of a clear, uninterrupted worksite next to the DC lines proving a stumbling block for previous Bushey PSU projects, the prospect of safe working with all 6 tracks blocked to traffic was the catalyst for a blockade to enable the Bushey PSU. Typically, it takes around a year’s planning for a six-day blockade of the type required at Bushey. In this instance the team had around 12 weeks from concept to commencement. Due to the increased risk profile engendered by the highly compressed schedule, the project was let on an open book, cost reimbursable contract.
As part of a wider Department of Transport funded programme of overhead line works on the WCML, between Wembley and Bourne End, the Bushey PSU entailed removing a series of oil-filled transformers and updating with an Auto-Transformer System (+/- 25kv 50kv system), which reduces voltage drop, extends range, and minimises electro-magnetic interference. The work encompassed creating three new substations and refurbishing two existing units.
Delivery had to account for the unusual configuration at Bushey, where the AC overhead lines are positioned directly adjacent to the DC conductor rails on the slow lines. The WCML uses overhead AC (25kV) for express trains, while local services, particularly on the slow lines historically operated on DC third rail.
The project was completed within the compressed schedule: 12-weeks planning and six-day blockade, with three miles of track fully enabled and ready for commissioning.
Multiple overlapping factors enabled this significant achievement. Having tested the robustness of the unconventional proposal Octavius’ leadership demonstrated their conviction in the team’s ability to deliver by putting their weight behind the plan. This enabled the delivery team leadership to assemble a unique pool of subject matter experts from across Octavius to support the attainment of the aggressive schedule.
The ability to quickly mobilise the supply chain was a significant factor. This was achieved by using existing, proven companies, rather than going to the market. Value for money was ensured by benchmarking the proposed team against previous projects. Among the organisations entrusted with enabling the rapid mobilisation were Pod Trak, electrical designer Navitas, and Global Rail Infrastructure Group, which like Octavius is an RSK company. Along with known capabilities this approach meant existing interpersonal relationships could be tapped into – vital when speed is essential.
With the risk profile the schedule engendered, building strong and trust-based relationships with the customer was key. In part this was achieved by senior members of Octavius team co-locating with Network Rail’s Bushey team from autumn onwards.
The golden thread running through all of this was creating a culture of openness and trust across all of the people and organisations key to meeting the 12-week planning deadline. As challenges arose they were overcome by allowing common purpose to guide the solution. This was achieved with weekly check-ins by the project leaders with all areas of delivery with a ‘no-blame’ culture giving everyone the chance to share their insights. As a result blockade time was maximised in every single way – bringing certain elements forward whilst tackling site challenges uncovered in real time.
Successfully completing this tricky section of enabling works was a key item in the overall planning and commissioning of the full Bushey PSU in 2027/2028, by removing what had previously proved a stubborn obstacle. Octavius is able to look back at Bushey PSU as a successful and rewarding project, and look forward to the possibility of maintaining the continuity of proven teams and relationships established at Bushey for the delivery of the remaining Wembley to Bourne End programme.
