Pleasant Street Incline

I've done some light research on the abandoned tunnel between Boylston Station and the Pleasant Street Incline. I understand this section was for the trolleys to enter the subway system but wasn't used by the subway system itself. Was the lack of ridership because people had to transfer at Boylston or was it really the automobile that did it in? Why didn't the MTA ever consider expanding the subway system down to Egleston and City Point, or at least have the trolley's run further inbound to Scollay Square or something to create a better one stop ride without a Boylston transfer? Also, I assume there was an underground loop near Boylston for the trolleys to turn around?

From 1898 to 1901 and 1908 to 1961, service using the Pleasant Street Incline did run into the subway. It was initially a dozen or more services using the portal, which was quickly whittled down as outlying streetcar lines were rerouted to El stations. (From 1901 to 1908, only the El used Pleasant Street Incline; all streetcar lines entered at Public Garden Portal and looped at Park Street.) Because the Pleasant Street Incline used the outer tracks in the subway, services mostly ran through to North Station or Lechmere rather than looping at Park Street.

After 1938, the only services still using the portal were the City Point line (now the #9 bus) and the Egleston line (now the #43); both used the surface loop at North Station (Canal Street Terminal). The City Point line was replaced by buses in 1953, and the Egleston line was cut back to Lenox Street in 1956.

On November 19, 1961, buses replaced streetcars on the surface section of the #43. Streetcar shuttle service ran between Pleasant Street and Boylston; this was likely what you were thinking of. It was operated with two double-ended PCC cars - one on each track. This operation was the only time that service using the incline did not run through the rest of the subway. It was a short-lived operation that ended on April 5, 1962.

Was the EL only meant to be temporary until the Washington St. Portal opened?

It's not quite clear whether BERy planned to keep the El in the Tremont Street Subway, or to eventually move it to a new subway, at the time that it was converted in 1901. Almost immediately it became clear that the streetcar subway was not ideal for the El trains and public opinion favored a new tunnel. The legislature passed a bill in mid-1902, and Washington Street soon became the favored route.