Owner
London Underground
Client
Arcadis
Cost
£150 million GBP
Timeframe
February 2017
— June 2017
Services performed
Feasibility study and conceptual design.
Description
Holborn is a LU station in central London. It is served by the Central and Piccadilly lines. Demand for both lines at Holborn is high. The principal design challenges are the close proximity of the proposed tunnels to existing operational tunnels, complex tunnel geometry and alignments, limited clearance to existing buildings, restricted work sites and strict settlement criteria. The lining system is a double shell lining with both linings considered part of the permanent load bearing structure.
Geology
The alignment of the tunnels mainly crossing limestone formations with laminated black shales of varying thickness and locally glacial till.
Location
London, UK
Highlights
- Close proximity to existing operational tunnels
- Complex tunnel geometry and alignments
- Approximately 725 linear meter of SCL tunnel
32 visualisation of existing Holborn underground station
Archive photo of heading of escalator tunnel (1931)