Beijing Subway Line 1, as the earliest subway line in Beijing, lies under Chang'an Avenue in a linear shape, passes through the most prosperous downtown area, and exchanges with many lines for passenger flow. It is one of the lines with highest operational density, whose average passenger capacity exceeds one million per day.
The construction of western section (Pingguoyuan Station– Fuxingmen Station) of Beijing Subway Line 1 started in 1965 and entered into service in 1974. It adopted relay-based interlocking and frequency shift track circuit with all the signaling equipment localized. In the 1990s, it went through the technical renovation by introducing the jointless track circuit from Westinghouse, a British company. In order to unify the signaling equipment modes, the extension line (Fuxingmen Station–Sihui Station) of Line 1, continued to introduce jointless track circuits from Westinghouse, and meanwhile adopted localized relay-based interlocking equipment. The extension line was put into operation in 1999. As the signaling system of Line 1 was put into use long ago, the aging of the equipment reduced the system availability and greatly affected the improvement of transport capacity. As the city size of Beijing has been expanded and migrant populations has swarmed in constantly, greater transport capacity of urban rail transit and improved system safety and reliability are demanded.
Therefore, Beijing Subway initiated the renovation of signaling system for the Subway Line 1 in 2012 and adopted CASCO’s Urbalis 888 CBTC networked signaling system, so as to meet the operation requirements for highly dense operation and less operation interval, greater reliability, safety and comfort.
As one of the busiest lines in the city, Beijing Line 1 cannot stop normal operation during signaling system renovation. So the construction and testing of signaling system were all conducted at night after operation, leaving the time for effective construction less than three hours. The renovation also involves maintenance of existing equipment, and interdisciplinary cross construction, making it more difficult with greater challenges.
Beijing Subway Line 1 is about 34km long, with 25 stations, 2 depots (respectively in Gucheng and Sihui), 1 testing line (at Sihui Depot) and 1 control center, as well as 70 6-car marshaled trains.
In order to ensure the continuous operation of the existing signaling system, it is essential to control time for system switch, make detailed testing plan, design a prototype section to conduct system testing in advance, and conduct the multi-train tracking test on the operating line at night, including single-train function test, two-train tracking test, five-train tracking test, and multi-train tracking test of 20 trains, 30 trains and 60 trains. The multi-train test is an important step to check the functions, performance and stability of the new signaling system, laying a foundation for the operation of the new system.
On December 7, 2015, Beijing Subway Line 1 officially started using the new system, CASCO’s Urbalis 888, for passenger-carrying trial operation.
Escorted by the new signaling system, the mainline tracking interval can be as short as 90s, turn-back performance up to within 120s, minimum departure interval cut from 2.05min to 2min, and operational efficiency up by 4.2%. The system has been running stably so far.