In the late 1990s and early 2000s, the MTA began automating the subway by installing CBTC, which supplements rather than replaces the fixed-block signal system; it allows trains to operate more closely together with lower headways. The BMT Canarsie Line, on which the runs, was chosen for pilot testing because it is a self-contained line that does not operate in conjunction with other lines. CBTC became operational in February 2009. Due to an unexpected ridership increase, the MTA ordered additional cars, and increased service from 15 trains to 26 trains per hour, an achievement beyond the capability of the block system. The total cost of the project was $340 million.