The Massachusetts Bay Transportation Authority operates three specially designated crosstown bus routes in the Boston, Massachusetts, United States area, called CT1, CT2 and CT3, and intended as limited-stop buses connecting major points. These crosstown buses are designated differently from older de facto crosstown routes, such as the #1 (Harvard/Holyoke Gate - Dudley Station via Massachusetts Avenue) and the #66 (Harvard Square - Dudley Station via Allston & Brookline Village). The bus services are very similar in equipment and fare structure, except that the CT routes have more-limited stops. Both types of routes suffer from frequent delays, unreliable service, and bus bunching caused by congestion in heavy mixed traffic.
The CT crosstown buses were envisioned as a first phase in a gradual improvement of circumferential service connecting the radial "spokes" of the Metro Boston rapid transit system, planned to culminate in the Urban Ring. The CT routes run weekdays only; all buses in this service have bicycle racks and are based out of the Albany Street garage. The routes were first introduced in September 1994 and have been modified since.
With the suspension of the Urban Ring project (due to lack of funding), the crosstown bus routes remain as an interim service to meet demand for circumferential routes that bypass the crowded subway stations in the hub of downtown Boston. As a symbolic indication of future service upgrade plans, bus stops on the CT routes are sometimes designated as "stations".
The CT1 Central Square, Cambridge - B.U. Medical Center/Boston Medical Center via M.I.T. (internally coded 701) runs between Central Square in Cambridge and the B.U. Medical Center/Boston Medical Center, mostly along Massachusetts Avenue. The majority of its route is a limited-stop version of the 1. Transfers to the 1 are possible at most of the stops. CT1 service has not been substantially modified since its 1994 inception.