The line between Shepherd's Bush and Bank was formally opened on 30 June 1900, public services beginning on 30 July. With a uniform fare of 2d the railway became known as the "Twopenny Tube". It was initially operated by electric locomotives hauling carriages, but the locomotive's considerable unsprung weight caused much vibration in the buildings above the line, and the railway rebuilt the locomotives to incorporate geared drives. This allowed higher-speed and lighter motors to be used, which reduced the overall weight of the locomotive as well as the unsprung weight. The railway also tried an alternative approach: it converted four coaches to accommodate motors and control gear. Two of these experimental motor coaches were used in a 6-coach train, the control gear being operated by the system used on the Waterloo and City Railway. The modified locomotives were a considerable improvement, but the motor coaches of an even lower weight were much better still. The CLR ordered 64 new motor cars designed to use Sprague's recently developed traction control system. The CLR was exclusively using the resulting electric multiple units by 1903.