Manhattanites can now rest easy knowing that any bus on the island is trackable by smartphone, web or text message, thanks to the MTA's rapidly expanding BusTime service.

The new trackable buses join 21 routes in the Bronx and 20 on Staten Island that connect to Manhattan, with the service expected to expand to all Manhattan-bound Queens and Brooklyn buses in the next six months, according to the MTA.

The feature was added today on the M1, M2, M3, M4, M5, M7, M8, M9, M10, M11, M14A, M14D, M15, M15 SBS, M20, M21, M22, M23, M31, M35, M42, M50, M57, M60, M66, M72, M79, M86, M101, M102, M103, M104, M106 and M116. Bus Time was already in place for the M34 and the M34A.

BusTime uses data from GPS devices mounted in the buses, which is then sent to the MTA server and integrated with location data and route info. Passengers can get bus info on the web or their smartphones by clicking, or by texting an intersection, street address or bus stop code to "511123" from any cell phone. Confused? It's cool. There's a video:

Mind you, Bus Time and bus clocks are not the same thing. Bus clocks are devices mounted in bus shelters themselves that alert passengers to arrival times—but those probably won't happen anytime soon, so don't hold your breath.