May 2012 in London Underground
If the SPTs are removed Train Operators will be solely reliant on the train radio for communication which the reporter states is only 95% effective. This could lead to a breakdown in communications in an emergency situation and is of particular concern in deep tunnels.
Could London Underground:
Response from London Underground
London Underground would like to thank the reporter for raising their concerns.
On 1 January 2012 Signal Post Telephones (SPTs) used to contact London Underground Signalling Staff were taken out of operational use on the District, Metropolitan, Circle and Hammersmith, Bakerloo and Victoria Lines. The operational use of SPTs on the Central Line will stop at the beginning of February 2012.
After the above dates all staff should only use radio, or if appropriate auto phones, to contact Signalling Staff. All SPTs will be decommissioned in a rolling programme commencing on 2 January 2012. Once a SPT has been decommissioned it will be bagged and clipped and the sign adjacent will be displayed.
In response to the concerns raised by the reporter it should be noted that the radio system is far more reliable than indicated. The system is cellular in nature and should a single cell fail the adjoining cells provide extended coverage to all trains in that area, thus recovering any loss of radio signal. In addition all radio equipment on the trains is fully tested before a train enters service. At present the system has a reliability score of 99.9995% which represents a score of 0.0005% of lost time, less than 3 minutes downtime for service affecting radio faults, during running hours over 12 months.
In addition it should be noted that all Train Operators have been issued with a hand portable radio, which can be used as a backup should the train borne radio equipment become faulty, as perLondon Underground Operations Rule Book 6.