Because the line is the busiest on the system, there are significant problems that overstretch its capabilities. In particular is the station Vykhino, which was built with too small a capacity to handle the congestion, making it the busiest on the system. In 2004 a severe reconstruction increased the area of the platforms and gave the station a desirable facelift. Nonetheless, that was insufficient to solve the problem, and in 2013 the line was extended to the south-eastern districts of Moscow outside the Ring Road with the opening of Zhulebino and Lermontovsky Prospekt stations. By September 2015, the line has reached a neighboring city of Kotelniki with the construction of an eponymous metro station there. The Kotelniki station opened on 21 September 2015 and became the new terminus of the southeastern radius.