 The previously used "X" routes have been dropped in favor of "SIM," or Staten Island to Manhattan, routes.This was the result of the two-year Staten Island Bus Study conducted by MTA, launched in 2015, which analyzed trip performance data, ridership profiles and extensive customer input, to determine the most effective way to reconfigure the network.All routes are operated by New York City Transit, except for the SIM23 and SIM24, which are operated by Academy Bus.