Tunnel Telephone
Project Description
London Underground operates a system for Emergency Traction Current Discharge (System) – ETCDS, or ‘Tunnel Telephone’ (TT).
The system is a pair of un-insulated ‘pinch-wires’ adjacent to each tunnel section and telephone handsets on stations, or the trackside, which allow train operators to discharge the electric current on the 3rd and 4th rails of the power supply network.
Work Streams
- Demands of new rolling stock
- Integration with existing systems
- Short working hours
- Working on safety critical infrastructure

Description of Works Carried Out
ADComms’ design elements included all engineering disciplines (communications, electrical, mechanical, civils and human factors), and Lead Designer for both Conceptual (equivalent to RIBA C/C & GRIP 4) and Detailed Design (equivalent to RIBA E/F and GRIP 5) stages.
The complete communications design involved both systems design and ‘component-level’ design of electronic and electro-mechanical relay circuits.
ADComms’ design function generated all assurance documentation for the build and commissioning phases, including comprehensive ‘Verification and Validation’ plans, detailed test schedules and documentation, and Inspection and Test Plans.
Case Studies
















