Line S1 (Chinese: S1线; pinyin: S Yī Xiàn) or Mentougou Line (Chinese: 门头沟线; pinyin: Méntóugōu Xiàn) formerly known as Datai Line (Chinese: 大台线; pinyin: Dàtái Xiàn), or Beijing Maglev Trains (Chinese: 北京低速磁悬浮; pinyin: Běijīng Dīsù Cíxuánfú) is a magnetic levitation train currently under construction. It will be operated by the Beijing Suburban Railway. Line S1 of BCR will start from the Dinghuiqiao North Number Five Road on the West Fourth Ring Road, and will go west towards Mentougou. Reports in July 2014 say the line will commence operation in November or December 2015. Once completed, it will be China's 2nd commercial maglev train in operation.
Trains will use the low and middle speed magnetic levitation technology which can give a top speed of 105 kilometers per hour.
The line is part of Beijing's attempts to tackle environmental problems caused by heavy car use, coal burning and fast urbanisation. Another reason is that many cities are reportedly upgrading their urban rail systems and introducing green technologies. The maglev train produces zero emissions unlike conventional trains that run on diesel or coal.
Six coach maglev trains will be built by the China CNR Corporation, making it the first domestically built Chinese maglev train.