of railroad improvements undertaken by the City of Philadelphia and the Pennsylvania Railroad, a new section of tunnel from 22nd Street to 46th Street was started in 1930, which would allow for removal of the elevated structure east of 46th Street and the old Schuylkill River Bridge. Coinciding with this project, a new bridge was also to be built across the river for automobile traffic; this raised the level of the street to permit the roadway to pass over the underground tracks of the Pennsylvania Railroad near their new 30th Street Station. This resulted in a reduction of vertical clearance under the old elevated structure from to only , which was expected to be only a temporary problem until the new subway tunnel was complete. Funding ran out before the subway extension could be finished. Although streetcar tracks were installed in the new Market Street Bridge, there was insufficient clearance to pass any cars under the elevated, and no service would ever be provided over the new tracks. Subway construction resumed in 1947, and the current configuration opened on November 6, 1955. The old elevated structure was removed by June 20, 1956. While the track was redirected into the new subway, a short stub of the old elevated structure remained at 45th Street until the reconstruction of the Market Street Elevated in 2008. In addition to extending the Market Street subway tunnel west to 46th Street, with new stations at 30th, 34th and 40th streets, a new trolley tunnel was built under Market, Ludlow and 36th streets and the former Woodland Avenue, leading to a new western portal at 40th Street for routes 11, 13, 34 and 36 (route 10 trolleys use a separate portal at 36th and Ludlow). New stations for the trolleys were constructed at 22nd, 30th, 33rd (between Market and Ludlow), 36th (at Sansom), and 37th (at Spruce) streets. The 24th Street trolley station and tunnel portal was abandoned. The tunnel mouth was visible from Market Street until the Philadelphia Electric Company (now PECO) built the PECO Building on the site in 1969. Skip-stop operation began on January 30, 1956. In the original skip-stop configuration, in addition to the A and B stops shown on the map above, 2nd and 34th Street were "A" stations, and Fairmount (replaced by Spring Garden) was a "B" station; the A and B designations at these stations were changed to "All-Stop"