was sprung to reduce vibrations; for the second solution, two six-carriage trains were formed that had the two end carriages converted and provided with driver's cabs and their own motors so they could run as multiple units without a separate locomotive. The lighter locomotives did reduce the vibrations felt at the surface, but the multiple units removed it almost completely and the CLR chose to adopt that solution. The committee's report, published in 1902, also found that the CLR's choice of 100 lb/yard (49.60 kg/m) bridge rail for its tracks rather than a stiffer bullhead rail on cross sleepers contributed to the vibration. Following the report, the CLR purchased 64 driving motor carriages for use with the existing stock; together, these were formed into six- or seven-carriage trains. The change to multiple unit operation was completed by June 1903 and all but two of the locomotives were scrapped. Those two were retained for shunting use in the depot. Extensions Reversing loops, 1901 The CLR's ability to manage its high passenger numbers was constrained by the service interval that it could achieve between trains. This was directly related to the time taken to turn around trains at the termini. At the end of a journey, a locomotive had to be disconnected from the leading end of the train and run around to the rear, where it was reconnected before proceeding in the opposite direction; an exercise that took a minimum of 2½ minutes. Seeking to shorten this interval, the CLR published a bill in November 1900 for the 1901 parliamentary session. The bill requested permission to construct loops at each end of the line so that trains could be turned around without disconnecting the locomotive. The loop at the western end was planned to run anti-clockwise under the three sides of Shepherd's Bush Green. For the eastern loop the alternatives were a loop under Liverpool Street station or a larger loop running under Threadneedle Street, Old Broad Street, Liverpool Street, Bishopsgate and returning to Threadneedle Street. The estimated cost of the loops was £800,000 (approximately £ today), most of which was for the eastern loop with its costly wayleaves. The CLR bill was one of more than a dozen tube railway bills submitted to Parliament for the 1901 session, To review the bills on an equal basis, Parliament established a joint committee under Lord Windsor, but by the time the committee