sentences:  The Blue Line is one of three heavy-rail subway lines in the Kanto region to use standard gauge track and a third rail electrification system (the others being the Ginza and Marunouchi lines of Tokyo Metro).As of 2018, this is the most recent subway line with third rail electrification to be constructed in Japan.Beginning in 1972, some private railroads in Tokyo began operating automatic ticket gates (those gates were introduced in 12 stations of the Musashino Line in 1973; six years later, the Hokusō Line began testing them).