In 1988, on the K264 train of the Beijing-Baotou Railway, passengers without seats rested at the junction of the cars. In the 1970s and '80s, insufficient transport capacity resulted in overcrowding in the train. YUAN RUILUN/For China Daily Railway is a nation's important infrastructure, and also the big artery of national economy and the backbone of the transportation system. But the driving factor, most economists agree, has been technological change and upgrade. The development of railways in different periods contains distinct feature of the time and has become a symbol of national progress.