Rail Tunnels in DC Electrified areas present complex challenges associated with the segregation of track side equipment/structure earthing, Overhead Contact Line Zone (OCLZ), Electrolysis, and power supply installations located outside the tunnel.
In General, rail tunnels comprise of traction overhead structure and rails, low voltage power supply for lighting and power, CSR, tunnel structures, comm’s equipment, metallic pipelines for other services such as fire and drainage. Effective control measures are essential for structure and equipment within OCLZ to mitigate equipment damage and prevent touch voltage hazards during maintenance. Moreover, Interface coordination with structural design is required to ensure compliance with the electrolysis requirements in accordance with relevant standards.
This paper details the case study of rail tunnel in Melbourne, highlighting hazards such as equipment within OCLZ zone, electrolysis effects and segregation requirements between the separately earthed systems.