of these services run more as commuter trains to/from satellite cities surrounding major urban centres or from downtown to the airport, as at Lanzhou. Conventional rail Z ("Zhida", 直达; Non-Stop Express) 'Z' trains, though their name in Chinese () technically implies a "non-stop" overnight train, some of these trains have several stops between the two stations. The majority have both soft sleepers and hard sleepers, while some Z trains have only soft sleepers. The top speed is 160 km/h. It uses the numbers Z1-Z9998 without regard to the number of railway bureaus entered. This series became available after the fifth rise in speed of the railway on April 18, 2004. Early on (2004–2006), all but one of the Z-series trains had either Beijing or Beijing West station as their destination or origin. As of 2009, Z-series trains also operated along the Yangtze Valley as well, providing overnight service from Wuhan to Shanghai, Hangzhou, Ningbo and Shenzhen. T ("Tekuai", 特快; Express) This series of trains have a limited number of stops along their routes, only in major cities, or in some instances stops for switching the driver or locomotive. The top speed is 140 km/h. T1–T4998 for the trains running through two or more railway bureaus, T5001–T9998 for the trains running within one railway bureau. The standard pronunciation on the railway system is "Te"() in Chinese. K ("Kuaisu", 快速; Fast) This series of trains stop at more stations than T-series. The top speed is 120 km/h. The standard pronunciation on the railway system is "Kuai"() in Chinese. K1–K6998 are used for the trains that run in more than one railway bureau, while K7001 to K9998 will be used for the trains that run in only one railway bureau. After April 18, 2004, N-series trains, which represent fast trains travelling exclusively within one railway bureau, were derived from K-series. Then all K-series trains travel on lines operated by more than one railway bureau. After April 1, 2009, N-series was re-merged to K-series after April 1, 2009. General Fast Train General fast trains (, which can be shortened to , ) are slower passenger trains that stop at around half of the stations along the way, resulting in a longer travel time than the fast trains. The top speed is 120 km/h. Route numbers are always four numeric digits—a numeric prefix from 1-5 followed by a 3-digit route number. Numbers 1001–1998 for the