Whitfield Consulting Services was pleased to be invited to complete detailed civil engineering design and other services as part of a major upgrade to the Piccadilly Line, for London Underground Limited and UK Power Networks Services (UKPNS). This exciting scope of work includes substantial upgrades to Manor House and Cobourg Street substations, plus new and upgraded 11kV and 22kV HV cable routes connecting those substations and continuing from Manor House to Wood Green – a route of approximately 10km in total.
The overall project to modernise the Piccadilly Line, which is planned to run until at least June 2025, will see design and construction works to upgrade several electrical substations, as well as the installation of new electrical infrastructure, electrical control systems, and cables along key parts of the line. The increased capacity will permit a new fleet of 94 modern trains, replacing the current 1973 stock. The new stock will improve reliability and accessibility for users of the system, as well as seeing a 23% increase in peak capacity, with trains running every 135 seconds at the busiest times. The overall work has been split into a number of parts, with Batches A & B awarded thus far, with UKPNS and WCS currently working on Batch B.
As well as an upgrade to capacity, the new trains will offer Piccadilly Line travellers air conditioning for the first time – a welcome modernisation.
Many challenges accompany any project within the Victorian architecture of the London Underground system. The old tunnels are only 3.56 metres wide, and already congested with significant accumulated infrastructure. For comparison, Elizabeth Line tunnels have been built with a diameter of 6.2 metres.
WCS was asked by UKPNS to perform all detailed civil engineering design. In addition, Nick Lowe, Associate and Contractors Responsible Engineer (CRE) at WCS, was named as Lead Civil Engineer for the project. This key role, approved by London Underground, involves liaising with lead engineering staff from UKPNS and London Underground throughout the project.
Work at Cobourg Street will include removal of walls, installation of new walls and creation of a new room, plus installation of new switchgear and other equipment.
At Manor House, space restrictions necessitate demolition of a telephone exchange building to make way for excavation and construction of three exterior coupling transformer pens. A replacement telecoms room will be installed on an upper floor with an external stairway constructed. Additional new equipment will also be installed, with floor strengthening required. Standard works such as creation of cable ducts and apertures are also needed in both substations.
The route between the two substations will see the addition of three new 22kV feeder cables, two new fibre optic control cables, plus decommission and removal of six existing 11kV cables. The continuing route from Manor House to Wood Green substation will require four 11kV feeder cables to be removed and replaced.
As well as completed tender support, work includes gauge assessments along the cable routes, to ensure all equipment will lie outside of the train envelope, various ground investigation and structural surveys, and dilapidation surveys at the two substations involved, to confirm that the works will not impact their overall structural integrity.
“The various assessments we have had to do are due in part to the ambition and complexity of the work”, comments Lead Civil Engineer Nick Lowe, “with 13 stages to the process at Cobourg Street. I’ve been involved with works at that substation for 15 years, and have worked on previous upgrades at Manor House over the years also, but this is an especially challenging project, and of course all being completed in a live environment, with the Piccadilly Line in use throughout. We are really excited to be a part of this project and grateful that our wealth of experience will doubtless prepare us for the challenge.”
The Piccadilly Line upgrade is the first element of the wider New Tube for London (NTfL) project, which may eventually see upgrades across the deep-level network, with obvious potential for new contracts awarded to partners who have worked successfully on the current phase of New Tube for London.