The MBTA’s real-time broadcasts of bus crowding data have been expanded to 23 bus routes, including the 111 to Chelsea.

Crowding information is now available for buses running on routes 1, 8, 10, 15, 16, 17, 21, 22, 23, 31, 32, 44, 66, 70, 71, 73, 77, 86, 104, 108, 109, 110 and 111.

The crowding data come from automated passenger counters (APCs), sensors installed at the front and rear doors that detect when someone boards or exits from the bus. Crowding levels are described as “Crowded,” “Some Crowding,” and “Not Crowded,” with standards based on lower crowding thresholds that allow for greater physical distancing on buses.

The information is included on the MTBA website and on the Transit app alongside real-time bus arrival and departure information, making it possible for riders to see, if one bus is too crowded, how long they may need to wait for less crowded buses to arrive.

The MBTA started broadcasting crowding information on nine initial routes last month. The 111, a route that essential workers rely on to cross the Mystic River into Boston, was initially omitted, has attracted widespread media attention this spring. Additional routes are being added as members of the MBTA’s Customer Technology Team verifies the accuracy of APC data in the field.