K-series trains
The K series is a train service speed level by China Railway. K stands for "kuaisu". However, they were used to likely to be the most commonly seen trains in China. Those trains make less stops than the number-only trains, but run at the same speed as them with a maximum speed of 120 km/h. For this, the K-series are sometimes mentioned as "Keng" by Chinese Railfans. Train numbers are written in the form of K*** or K****, but the letter K reads as "kuai " in station announcements and radio contacts.
History
1997–2004
The K-series trains first appeared in the first railway speed-up campaign as a service speed level, lower than the T-series but faster than the number-only series. The letter K was used in a train number for the first time in China. All the train numbers in the level were K***.2004–2009
With more and more short-distance K-series trains are made, the idea of N-series level was brought up in the fifth railway speed-up campaign. The train numbers were in the N*** form.2009–
The N-series was combined into the K-series again, for the appearance of K7*** series.Rolling stock
Most K-series trains run using air-conditioned China Railways 25G rolling stock for carriages.A few K-series trains use China Railways 25B, 25 or 22 rolling stocks, which are usually not air-conditioned and even coal-heated in winter. The 22 rolling stocks for K-series are most commonly seen in the northeastern part of China, where some railway lines cannot support 25G carriages to run on.
The 25T rolling stocks on K-series trains are really rare to be found. They are usually on the temporary trains, such as K5031/2 Dalian–Changchun service, which is only available on national holidays.
Train numbers
Trains are arranged into pairs, one for a direction for trains getting closer to Beijing or from branches to mainlines, and downward, divided in a slash. For example, the Beijing-Moscow train via Ulaanbaatar is numbered K3, while the returning one numbered K4, so the pair is K3/4. Some pairs of trains have more than two train numbers, for an upward trains may become a downward train for they pass through Beijing or certain points.In 2009, all the K-series trains are fixed to certain numbers arranged in a set of rules.
K-series trains numbered K1 to K3998 represents inter-bureau trains, which runs longer distances than others. Including international trains.
Train numbers K4001 to K4998 represents inter-bureau temporary trains, or former L-series.
Train numbers K5001 to K6998 represents inner-bureau temporary trains, also former L-series.
Train numbers K7001 to K9998 represents inner-bureau trains. Most of them run on regional routes, however some of them also run a longer distance, for the larger bureau responsibility areas.