Core Points - The Beijing Municipal Public Resources Trading Service Platform has announced the public bidding for the planning and research project of the northern extension of the R4 line, indicating that the planning work for this extension is set to begin [1] - The R4 line's first phase northern section has passed environmental assessments and is expected to officially commence construction within the year, with completion anticipated by the end of 2029 [1][2] - The R4 line will enhance transportation services in areas such as northeastern Chaoyang District, the Capital Airport Economic Demonstration Zone, and Shunyi New Town, facilitating better connectivity for residents [1] Project Details - The R4 line's first phase northern section will span approximately 21.3 kilometers, with 13.6 kilometers underground and 7.7 kilometers above ground, featuring a maximum speed of 120 km/h [4] - The project will include five stations, with four underground and one elevated, and will allow for transfers to other lines, including Line 3 and the existing Capital Airport Line [4][6] - Passenger flow forecasts indicate an average daily ridership of 151,000 by 2032, increasing to 303,000 by 2039, and reaching 726,000 by 2054 [5] Extension Planning - The current bidding aims to hire a third-party company to assess the necessity of extending the R4 line, with potential connectivity to Line 15, which is located approximately 1.5 kilometers north of the current endpoint [6][7] - The research will cover various aspects, including spatial development in Shunyi, feasibility analysis of station locations, and cost-benefit analysis of the extension [6] - The planning aligns with Shunyi's regional development strategy, which emphasizes connectivity and accessibility within the area [6][7]