Recently, Thales SEC Transport (TST) has successfully won the bid for the Shanghai rail transit communication system renewal and upgrading project in 2023 – the dedicated radio communication (Voice Trunking) system integration project for Line 7. TST has signed the contract and successfully conducted its initial design liaison meeting.

Construction of Shanghai Metro Line 7 began in late 2005, with the Phase-I project (Shanghai University Station to Huamu Road Station) becoming operational in December 2009,  the northern extension section (Meilanhu Station to Shanghai University Station) in 2010, Panguang Road Station and Liuhang Station in 2011, and Qihua Road Station in 2014.

Shanghai Metro Line 7, as the north-south main line, serves such central urban areas as Putuo District, Jing’an District and Xuhui District. With a total length of 44.35 kilometers, the line comprises 2.6 kilometers of elevated lines and 41.75 kilometers of underground lines, covering 33 stations (including 2 elevated stations and 31 underground stations). The line is equipped with the Chentai Road automated depot and Longyang Road parking lot, and operates 79 6-car A-type trains in total. 

Shanghai Line 7 Shanghai Line 7 has been in operation for 14 years, exemplifying combined operation involving both new and old vehicles due to substantial variations in the opening years of different sections and in the procurement timeline of vehicles across phases 1, 2, and 3. At present, the communication and other weak power system equipment has gradually entered the cycle of renewal and upgrading, among which, with the increase of the operation time, the dedicated radio subsystem of communication system has showed varying levels of aging damage and increased fault rate. As regular maintenance efforts have proven insufficient in mitigating existing security risks, it is imperative to enhance the system’s overall reliability and functional integrity through renewal and upgrading. 

Considering that the LTE integrated carrying system can be set up synchronously during the future signaling system overhaul to avoid redundant construction and wastage, TST has proposed an innovative plan tailored to the characteristics of Shanghai Metro Line 7. The plan involves retaining the original WLAN frequency hopping spread spectrum (FHSS) system at one end of the train while upgrading to the LTE system at the other end. Upon completion of the renewal project, two networks will be formed: Network A, where LTE carries CBTC and dedicated radio communication; Network B, where WLAN carries CBTC. This solution has provided a proactive technical path for the renewal and upgrading of communication system with the advantages of optimal cost, minimal changes and fastest upgrades, effectively addressing the limitations of the original Tetra narrowband technology, including limited radio communication bandwidth, single functionality and a shrinking industrial chain, while achieving the goal of prolonging the signaling system life by upgrading WLAN to LTE at a single end.

Leverage its system technology advantages, TST will remain committed to overcoming the renewal challenges posed by the mixed operation of different standard communication systems, including significant delays and packet loss rate and the need for on-board and trackside systems to simultaneously adapt to WLAN+LTE, thus ensuring seamless daily operation of the signaling system and complete the renewal process with “zero” interference through renewing the vehicle-ground communication network step by step.