2016, the platform screen doors was installed at Yong'anli station. By the end of 2017, all stations except were retrofitted with half-height platform screen doors, and all the screen doors were put into operation for the first time. Through operations with the Batong line In 2010, a CPPCC member Chen Dingwang, proposed that services on Line 1 and the Batong line should directly link, with through operations, reducing travel times and removing the unnecessary forced transfers at or . However, the Beijing Subway responded that Line 1's and Batong's signal systems are completely different, so through-operation will be more difficult to achieve, from an engineering standpoint. As of 2016, preliminary design and feasibility studies are underway to allow for through operations between Line 1 and Batong. On June 12, 2020, the project of the through operation of Line 1 and Batong line was approved by Beijing Development and Reform Commission. Through operation with the Batong line started on 29 August 2021. Other facilities Rolling stock for Line 1 is maintained at and . Restricted stations Beyond , Line 1 extends further northwest where it has several other stations: Gaojing () and Fushouling (). Gaojing station is in the military region. Fushouling station is actually outside the military region. These stations are not open for public use. Fushouling station will open to public in 2023. A proposal to open the Gaojing station to public is mentioned within 2022 and 2023 working plan of the Shijingshan District. Future Development Increasing capacity Due to Line 1's severe overcapacity problem, there are plans to introduce 7-car or longer trains. In order for this plan to proceed the oldest section of Line 1 between and , which only has platforms long enough to accommodate 6-car trains, will need to be lengthened. The newer section between and , formerly known as "Fuba line" during construction, has platforms long enough for 8-car trains. According to an interview to the director of Beijing Municipal Transport Commission in December 2022, they will introduce 7-car trains in the eastern section of Line 1 and the Batong line in future. Branch to Qinglong Lake East In 8 July 2022, an EIA document regarding Phase III construction of Beijing rail transport system (2022–2027) mentions a proposal about the branch line of Line 1. The branch line is a southwest-to-northeast line starts from Qinglong Lake East to Bajiao Amusement Park. It will be