the opening of Frankston and Sandringham lines. In 1885, a number of level crossing removal works occurred between Flinders Street station and South Yarra due to an increase in freight and passenger operations. These crossings were removed through a combination of lowering and raising the corridor. 20th century In 1915, the line between South Yarra and Caulfield was quadrupled, as part of level crossing removal works. This section of the line was lowered into a cutting to eliminate numerous level crossings. Power signalling was provided between Richmond and Hawksburn at the same time, then on to Caulfield in 1921. Electrification of the line to Dandenong occurred in two stages during 1922. In May 1922, the section from South Yarra to Oakleigh station was electrified, with the section to Dandenong being electrified later in December 1922. The electrification of the line allowed for the introduction of Swing Door electric multiple unit trains for the first time. Power signalling was extended to Carnegie in 1933, Oakleigh in 1940, and to Dandenong in stages between 1970 and 1972. The line between Dandenong, Pakenham and Traralgon was electrified in 1954. Initially single track, duplication of the line between Dandenong, Pakenham and Nar Nar Goon was completed in 1955 and 1956. Suburban services were extended beyond Dandenong to Pakenham in January 1975. Previously, the stations between Dandenong and Pakenham were only served by regional passenger trains connecting Gippsland to Melbourne. In 1981, Pakenham line services commenced operations through the City Loop, after previously terminating at Flinders or Spencer Street stations. The commencement of operations involved the service stopping at three new stations—Parliament, Melbourne Central (formally Museum), and Flagstaff. The Loop follows La Trobe and Spring Streets along the northern and eastern edges of the Hoddle Grid. The Loop connects with Melbourne's two busiest stations, Flinders Street and Southern Cross, via the elevated Flinders Street Viaduct. From 2025, the Pakenham line will no longer operate through the City Loop, instead operating via the north-south Metro Tunnel corridor. 21st century In 2002, after the closure of the nearby General Motors factory in 1991, General Motors station closed permanently after 46 years of operation. A 2007 restructure of train ticketing in Melbourne involved the removal of Zone 3, with Zone 3 stations being re-classified to Zone 2. This brought the cost of train fares down, improving system accessibility to the public. The Pakenham line received heavy investment during