Market–Frankford Line

The original subway tunnel from City Hall to the portal at 23rd Street, as well as the bridge to carry the line across the Schuylkill River, just north of Market Street, were built from April 1903 to August 1905.[5] Construction on the Market Street Elevated west from this point began In April 1904, and the line opened on March 4, 1907, from 69th Street Terminal to a loop around City Hall at 15th Street.[6] The line was elevated west of the river and underground east of the river. The tunnel was also used by streetcar lines, now SEPTA's subway–surface lines, that entered the line just east of the river and turned around at the City Hall loop. Philadelphia was unusual in that the construction of its initial downtown subway was undertaken using PRT (Philadelphia Rapid Transit Co.) private capital only, with no contribution from public funds.[7]

Extensions took the subway east to 2nd Street on August 3, 1908,[6] and via a portal at 2nd street and several elevated curves it reached the Delaware River between Market Street and Chestnut Street on September 7, 1908.[6] The Delaware Avenue Elevated (also called the Ferry Line, because of the multiple ferries across the river) opened on October 4, 1908,[6] as a further extension south along the river to South Street. The only two stations on this extension were Market–Chestnut and South Street.[6]

The total cost ("road and equipment expenditures") of the Market Street subway and elevated was $23,072,114 (equivalent to about $751,467,300 in 2022).[8]

Frankford Terminal in 1918, before the construction of the Frankford Elevated

The "first operating section" of the Frankford Elevated was planned to extend from Arch Street (connection with PTC Market Street line) to Bridge Street, 6.4 miles (10.3 km). Construction, financed by the City of Philadelphia and managed by the Department of City Transit, was started in September 1915.[9] At that time, construction was anticipated to require about three years.[10] However, construction was slowed because of World War I. By February 1920, 65 percent of the construction work had been completed and 15 percent was under contract. Of the remainder, plans had been completed for ten percent, leaving approximately ten percent of construction "yet to be arranged for".[9] The superstructure had been completed between Dyre Street (south of Pratt Street) to a point just north of Arch Street. However, only two stations had been completed, and six had not been started.[11] Signals, substations and cars had "yet to be arranged for".[12] In 1919, the Public Service Commission of Pennsylvania approved a connection between the Frankford and Market Street lines in 1919, with signals and signal tower to be built by PRT.[9] But the Philadelphia City Solicitor determined that the connection could not be built until a contract for operation had been signed and approved by the PSC.[13] This did not take place until 1922. The line was dedicated on November 4, 1922, and opened for service on November 5.[14][15] Trains from 69th Street alternated between the Frankford and Ferry Line terminals.

Total expenditures by the city for the Frankford El "with its track, substations, equipment and certain rolling stock" was $15,604,000 to December 31, 1929.[16]

The planned — and authorized — second section of the Frankford El, Bridge Street to Rhawn Street with intermediate stations at Comly Street, Levick Street, Tyson Avenue, and Cottman Avenue, 3.0 miles (4.8 km)[11] was not built.

Following the opening of the Delaware River Bridge in 1926, traffic on the Delaware Ave branch declined sharply.[17] Evening, Sunday and holiday service was discontinued on January 24, 1937. Sunday and holiday service was restored from May 30 to September 13, 1937, and again from July 3 to September 12, 1938. The last day of service was May 6, 1939, with the last train departing South Street at 7:00 p.m.[18] Thereafter, the line was closed and dismantled. A replacement bus service was started in 1943 to serve wartime traffic, and continued in operation until 1953.[17] The old interlocking tower and stub remains of the junction with the Ferry Line survived until the realignment into the median of I-95 in 1977.

As part of a program 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,[19] 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 20 feet (6.1 m) to only 8 feet (2.4 m),[19] 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.[19] 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.[19] Subway construction resumed in 1947,[4] and the current configuration opened on November 6, 1955.[4] The old elevated structure was removed by June 20, 1956.[4] 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,[4] 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[19] until the Philadelphia Electric Company (now PECO) built the PECO Building on the site in 1969.

Skip-stop operation began on January 30, 1956.[4] 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" because of increased patronage in the 1990s. As I-95 was built through Center City Philadelphia in the late 1970s, part of the Frankford El was relocated to I-95's median, and the Fairmount station was replaced by Spring Garden, on May 16, 1977. Skip-stop operation, which was only available during rush hours on weekdays, was discontinued on February 21, 2020.[20]

Market–Frankford Line train at 11th Street station in 2019

Between 1988 and 2003, SEPTA undertook a $493.3 million[21] complete reconstruction of the Frankford side of the Market–Frankford Line between Frankford Transportation Center and the 2nd Street portal. The new Frankford Elevated was built with new stringers and deck installed on the original columns, thus giving not only a reduction in cost, but also reducing the street-level impact on adjoining neighborhoods. The old ballasted trackage was replaced with a direct fixation system. In addition to the new Elevated structure, all of the stations were replaced with new stations with higher boarding platforms and elevators, allowing customers with disabilities to easily board and depart from Market-Frankford trains. The reconstruction of the Frankford Elevated structure was mostly complete by 2000, with the exception of the elevated section from Dyre Street (just to the south of the Bridge-Pratt terminal) to the Frankford Yard entrance. The basic design of the bearings of the reconstructed Frankford Elevated, however, was not appropriate for the repetitive loading from the train traffic. The bearing design did not take into consideration the interaction of the concrete haunches with the steel stringers when loaded by the passing train;[22] and the concrete has started to fracture and drop onto the street below. The problem was first discovered in 1997, but at that time was simply attributed to faulty construction, without evaluation of the root cause. As a temporary fix, SEPTA has installed 10,000 metal mesh belts on the underside of the structure. Estimates for a permanent fix placed the cost at about $20 million, and SEPTA has filed suit against the engineering companies that contributed to the design flaw to recover part of the repair cost.[23][24] Work on the permanent fix is currently underway.

SEPTA then undertook a $567 million complete reconstruction of the Market Street Elevated between 69th Street Transportation Center and the 44th Street portal between 1999 and 2009.[25] The New Market Street Elevated was an entirely new structure, utilizing single-pillar supports in place of the old-style dual pillar design, allowing the Pennsylvania Department of Transportation (PennDOT) to undertake a planned widening project on Market Street to four lanes between 63rd Street and 44th Street. In addition to the new Elevated structure, all of the stations (including Millbourne) were again replaced with new stations having higher boarding platforms and elevators, allowing customers with disabilities to easily board and depart from trains. The reconstruction of the Market St. Elevated superstructure was completed in 2008, and the last station, 63rd Street, was completed and reopened on May 4, 2009.[26] The Market St. Elevated is not of the same design as the Frankford Elevated, so it does not share any of the Frankford design flaws.

In 2003, the Bridge-Pratt terminal was closed and replaced with the new Frankford Transportation Center.[27] After Bridge-Pratt closed, the station platforms and the remaining unrebuilt elevated structure above Frankford Avenue and Bridge Street were demolished. The new $160 million Frankford terminal facility was built on a tract of land off Frankford Avenue formerly part of the adjacent bus and trackless trolley service depot.

In November 2011, the Federal Transit Administration (FTA), through its competitive Fiscal Year 2011 Sustainability Initiative, awarded $1.4 million to SEPTA to install a "wayside energy storage system" on the Market–Frankford Line. The system stores energy from braking trains in a battery that may be used later.[28]

An extension of the Market–Frankford Line from Frankford to Roosevelt Boulevard and Bustleton Avenue had been proposed in 2011, but no plans or extension construction has taken place.[29]

In the City of Philadelphia's 2021 Transit Plan, one proposal in their list of possible high-capacity transit expansion plans was an infill station located between the MFL's 15th Street and 30th Street stations. The 15-block area between the two stations was cited as being a major part of Philadelphia's CBD since the 1960's. The plan stated that an infill station on the Market-Frankford Line in this part of the city would not only provide better access for major developments, but it would also create transfer opportunities with frequent north-south bus routes on 19th and 20th Streets. However, the 2021 Transit Plan said that while initial studies showed such a station would be feasible and highly beneficial, it would be very difficult and expensive to build.[30]

Proposed new logo for the Market–Frankford Line under the SEPTA Metro wayfinding project[31]

The line operated "Lifeline Service" due to the COVID-19 pandemic, with trains bypassing Millbourne, 63rd Street, 13th Street, 5th Street/Independence Hall, 2nd Street, York–Dauphin, Somerset, Tioga, and Church stations as of April 2020. All stations except 5th Street were reopened in June 2020.[32]

In 2021, SEPTA proposed rebranding their rail transit service as "SEPTA Metro", in order to make the system easier to navigate. Under this proposal, services along the Market–Frankford Line will be rebranded as the "L" line with a blue color.[33][31][34]

A local trip along the entire line takes about 40 minutes. Trains run from approximately 5:00 am to 1:00 am, with a timed-transfer at 12:30 am at City Hall station to connect with the Broad Street Line based on final trains. The Market-Frankford Owl bus service replaces the subway throughout the night Monday through Friday mornings, stopping at the same locations as the subway trains. The line itself ran 24 hours a day until it was eliminated in 1991; it was reinstated on June 20, 2014, for Friday and Saturday overnights only on a trial basis. It was made permanent on October 8, 2014. Since 2014, the line runs nonstop from 5:00 a.m. on Friday to 1:00 a.m. on Monday morning, until the COVID-19 pandemic, in which all overnight service is now replaced by the Market-Frankford Owl bus.

The Market–Frankford Line carries a daytime frequency of 6 minutes on weekdays (off peak), and 10 minutes on weekends. It runs every 12 minutes during night service, with a 15-minute headway during night owl bus service. Prior to the COVID-19 pandemic, late night rail service was provided on Friday and Saturday nights.