MBTA key bus routes

Key bus routes of the Massachusetts Bay Transportation Authority (MBTA) system are 15 routes that have high ridership and higher frequency standards than other bus lines, according to the 2004 MBTA Service Policy.^[1] Together, they account for roughly 40% of the MBTA's total bus ridership.^[2] These key bus routes ensure basic geographic coverage with frequent service in the densest areas of Boston, and connect to other MBTA services to give access to other areas throughout the region.^[3][4]

In recognition of their function as part of the backbone MBTA service, the key bus routes have been added to newer basic route maps installed in subway stations and other public locations. These schematic route maps show the rail rapid transit routes, bus rapid transit routes, commuter rail services, and key bus routes. The key routes have been treated as a distinct category for the purpose of service improvement, such as trial runs of late-night service, and due to the high volume of passenger traffic they carry, both individual routes and the category as a whole have been the subjects of urban planning and transportation engineering studies.