The LBSCR scheme, authorised in 1903, pioneered main-line rail electrification in the UK, and the first electric train ran on 1 December 1909. For the following three years, steam trains alternated with electrics, the latter operating every 15 minutes from 7.30am to midnight. Passenger numbers had fallen on introducing electric tramways in South London by 1.25 million in six months. In the first year of the rival line's electric operation passengers increased from 4 million to 7.5 million. The electrification used the overhead system at 6700 V AC, supplied by a power station at Deptford. After creation of the Big Four railway companies, the Southern Railway installed standard third-rail 660 V DC supply on 17 June 1928.