and the fact that other cities like San Francisco use the letter. A more likely theory suggests that it was originally planned for the last segment of Culver service to Manhattan, which was cut back to a shuttle permanently in 1959, right before the letters were introduced. S was still reserved for "Special" and SS began to be used for shuttles. Since the BMT was not amenable to the neat IND system, the TA had to make some compromises. They tried to follow the IND system of single-letter expresses and double-letter locals, but the system began to break down under the complex BMT routings. Where on the IND a local simply doubled the express letter (A Eighth Avenue Express, AA Eighth Avenue Local), some lines had multiple local services with different routings. For instance the two Brighton Local services, one via the Manhattan Bridge and the other via the Montague Street Tunnel, were designated QB and QT respectively. The TA had no specific lettering plan for the two Wall Street special rush-hour services, so it just designated these M (Nassau Street Express) temporarily, a letter reserved for use on the BMT Myrtle Avenue Line's Nassau Street service. During this period, the TA did not change sign rolls on BMT equipment (the D-types and R16s) that carried numbers, so that on the Brighton Line, the R27-operated locals were signed QB or QT but the D-type-operated expresses continued to carry the number 1. Chrystie Street Connection In anticipation of the 1967 opening of the Chrystie Street Connection, which combined two major BMT and IND services as single routes and resulted in numerous other changes (especially on the 14 and 15), the TA decided to adopt universal systems of signage and nomenclature. The rationale was that this would make the system more consistent and more understandable for newcomers to the city and tourists, who were presumed to be uninterested in or even confused by historic or community names, or might not be native English speakers. Branch line names would be eliminated from signage and maps; all services that had Manhattan mainlines would be identified by those names only. Services would be identified only by letters or numbers wherever possible, even when announcing reroutings. Terminals would be identified by street names rather than community names where that existed. This had actually begun with the introduction of R-type equipment, when destinations such as Woodlawn and