Railway signals to a railway are what eyes and brain are to a man. In early days, the kerosene lamp was used to send signals to trains.
Made of three pieces of glass of different colors, the lamp could show three colors by refraction of its light. That was how the old railway signal system worked.
Such signal lamps started to step down from the historical stage in 1965 as they could hardly meet demands of the increased numbers of trains and improvements in their operational speed.
They were replaced by light signals installed along the railway, which were part of China's first domestically-developed railway signal system.
Powered by electricity, the new system could automatically control the railway to switch to the selected line and give the correct signal to trains.
As China lifted the curtain on the high-speed railway era, the train numbers rose again with some of them capable of operating as fast as 350 kilometers per hour.
The railway signal system was due for another updating. The new system is based on computers and is installed on the trains.
On Dec 30, 2019, the Beijing-Zhangjiakou High-speed Railway opened for service. It was China's first smart high-speed railway to be equipped with both high-speed train signal facilities and the BeiDou Navigation Satellite System, freeing it from manual control during departure, travel and arrival.
Thousands of sensors are also installed on the train body to monitor its condition, which guarantees safe operation.
As a central state-owned enterprise with expertise in railway signal systems, China Railway Signal and Communication Corporation Limited (CRSC) has played a key role in development and upgrading of China's railway signal systems.
(Executive editor: Wang Ruoting)