Development of an optimised energy efficient traction power system upgrade for London Underground's Northern Line

Introducing a Transmission Based Train Control signalling system on London Underground's Northern Line facilitates an appreciable increase in train service frequencies, impacting the existing 630V DC ‘four rail’ traction power system. Extensive operational and traction power simulation modelling was undertaken to investigate train voltage regulation especially under electrical outage and perturbed operating conditions. Traction power system upgrade options were developed comprising ‘low loss’ Composite Conductor Rail (CCR), increasing system voltage to 750V, and parallel cabling. The upgrade options were evaluated in terms of equipment quantities, costs, installation programmes, and energy losses (including tunnel environmental impacts), and a single option taken forward for implementation.