Guest writer: Caroline Bacher
Since 2007, Network Rail has steadily been replacing the overhead line equipment (OLE) on the Great Eastern line from London Liverpool Street, first to Chelmsford and then on to Southend Victoria. The old system had reached the end of its lifespan was increasingly becoming a reliability issue.
A key goal for the project team was to reuse as much of the existing infrastructure as possible.
Working with OLE specialist Furrer+Frey, Network Rail developed a new, auto-tensioned, modern 25kV AC system that retained a vast number of existing steelwork structures in order to save costs, reduce risks and minimise disruption and impact on service. It also aimed to address known reliability and performance issues, and in such was tailored to the region and its specific challenges.
Upon completion of the new system’s development, a rolling programme of electrification renewal was undertaken on this route and, after 10 years, is due to finish. Once some initial teething issues were ironed out on the first few sections, both design and installation went smoothly and without major drawbacks as the teams grew closer together and the supply chain worked well on all levels. Furrer+Frey and the Network Rail in-house installation team OCR were working hand-in-hand to deliver the renewals without major impact on the service.
Moving on to Thameside
With the Great Eastern largely complete, Network Rail has now started to plan the next phase of this programme, renewing the OLE on the Thameside route out of London Fenchurch Street, the line that was previously known as LTS (London – Tilbury – Southend).
Like the Great Eastern, the first sections of Thameside were initially electrified with DC equipment in the 1940s. This was further extended in the 1960s at 6.25kV, before finally being converted to the more common 25kV AC in the 1980s. As with Great Eastern, the initial DC sections were installed using fixed tension equipment, meaning that there are no balance weights or tensioning devices to keep overhead wires taught and instead wires are fixed at a specific tension. This means that, on hot days, wires can sag requiring speed restrictions to be put in place.
Since the Thameside system was mainly installed in the 1960s, reliability had fallen over time and service disruptions had become more common. The route has been installed primarily with Mk1 equipment, which is an early UK electrification system, thus the current project has become known as the Mk1 Renewals project. Due to the age of this Mk1 equipment and its inherent reliability issues, there is an increased maintenance cost associated with this life-expired equipment.
Once again, Network Rail decided to renew the electrification equipment but retain the structures wherever possible, to minimise costs and possession requirements.
At the end of 2018, Furrer+Frey won the contract to be the lead designer on this project. This move makes it possible to replicate the success of the Great Eastern project, continuing the successful and collaborative working relationship between Network Rail and Furrer+Frey and bringing all their relevant experience and expertise forward to the new project.
This consistency is also maintained on an individual level, as many staff members from the Great Eastern project teams have now moved across to the Mk1 Renewals project, both within Furrer+Frey and Network Rail, as well as Network Rail’s long-term partner CPMS, project manager for the works, and the in-house installation team OCR. Finally, Furrer+Frey is once again supported by OLE Ltd, another carry-over from the Great Eastern.
The collaborative spirit of the teams working together to deliver the project is ensured by a number of contractual elements to which all parties are committed. These include progressive design reviews, as an informal means to align and manage expectations, and a series of collaboration workshops to define behaviour and communication rules and address any issues outside the technical core of the project.
Caroline Bacher is head of UK projects with Furrer+Frey.
This article first appeared in Issue 177 of Rail Engineer, Aug/Sep 2019.
