BVG Class F
| Company type | Train series |
|---|---|
| Industry | Public transport |
| Predecessor | BVG Class D, BVG Class DL, BVG Class C |
| Founded | 1973 |
| Successor | BVG Class H |
Area served | Berlin U-Bahn large-profile lines |
| Products | Electric multiple units for subway service |
| Parent | Berliner Verkehrsbetriebe (BVG) |
BVG Class F
The BVG Class F represents a series of trains specifically engineered for the large-profile lines of the Berlin U-Bahn network. Between 1973 and 1994, a total of 257 two-car sets were produced across seven distinct production runs, each exhibiting variations in design and technical specifications.
Testing began in 1973 with the prototype unit numbered 2500/01, leading to full-scale manufacturing starting the next year. By 1981, 112 units from batches F74 through F79 had been delivered to West Berlin, effectively replacing the last remaining pre-war BVG Class C trains. From 1984 until 1994, an additional 145 units incorporating various enhancements were built, partially substituting rolling stock from East Berlin’s system following German reunification.
The BVG Class F was eventually succeeded by the Class H trains, which were produced between 1995 and 2002.
Construction
These vehicles are constructed from lightweight metal with a straightforward design. They are easily identified by their rectangular headlights and, except for the F74 batch, feature a redesigned front end with larger windshields and wipers distinguishing them from their predecessors (BVG Class D). The Class F trains are an advancement over the Class DL light-metal units, offering a notably high maximum acceleration rate of up to .
Across the nine production batches, variations exist in both technical equipment and styling: The initial F74 batch maintains the front design characteristic of the Class D but incorporates different headlights. While early batches such as F74 and F76 utilized rollsigns, starting with the F79, split-flap displays showing line colors and numbers were introduced. These displays were also adopted by the F84 and F87 series. Later models, including F90 and F92, featured wider rollsigns; these were retrofitted onto earlier F79, F84, and F87 units during the 1990s and applied to refurbished F76 trains between 2015 and 2018.
Between 1984 and 1994 (batches F84 to F92), BVG implemented sliding plug doors instead of pocket doors, which simplified both construction and cleaning processes. The front design was slightly modified by adding a storm door connected by a black stripe running between the windows. Notably, unit 2770/71 of the F84 batch was equipped with an open gangway in the early 1990s as a testbed for features later incorporated into Class H trains.
Compared to earlier models, Class F trains are longer, allowing for wider doorways and driver cabs. They uniquely offer transverse seating arrangements—except for one experimental Class H train (unit 5018). All Class F units have a maximum speed of , although those equipped with three-phase propulsion systems (batches F79.3 through F92) were engineered to reach speeds up to .
Types
The fleet is broadly categorized into two propulsion types: F-Schaltwerker, which operate on direct current (batches F74 to F79), and F-Drehstromer, featuring three-phase propulsion (batches F84 to F92). Additionally, batch F79.3 employed three-phase technology as an experimental platform for future train models.
Unit 2578/79 from batch F76 was Europe’s first underground train trialing three-phase propulsion; however, it was converted back to direct current operation in 1980 since it was not intended for extended service.
Several units from batches F74, F76, and F79 were equipped with LZB automatic train control systems that operated on the U9 line until 1993. Following LZB’s deactivation in 1998, these systems were dismantled, though some cab components remained visible for years afterward.
From 2009 through 2017, refurbished two-car sets of F79 units served on the short U55 line, optimized for its three stations. These refurbishments acted as prototypes for extensive modernization programs encompassing all units from batches F74, F76, and F79.
Minor interior refurbishments took place in the late 2000s on batches F84 and F87, updating their brown interiors to light grey similar to those found in later models like the F90 and F92. An exception is unit 2826/27 (F87), which was temporarily withdrawn before returning in 2013 without any refurbishment; this unit remains the last Berlin U-Bahn train preserving the traditional brown interior following retirement of all A3L71 and F79 stock.
Refurbishment and Modernization
Prior to 2012, only a small number of F-Schaltwerker units were withdrawn from service, primarily due to derailments or significant faults, though the oldest vehicles were approaching the end of their operational lifespan. Because the BVG reduced its Class H order from 115 to 46 trains for budgetary reasons, there were no immediate plans to replace the Class F fleet.
In 2006, the initial Class F train (numbered 2500/01) was dismantled for material analysis, which confirmed that the car bodies remained structurally sound. As a result, between 2011 and 2018, all remaining F74 and F76 trains underwent comprehensive refurbishment. The upgrades featured interiors painted white with yellow handrails, increased space allocated for strollers and wheelchairs, and updated black seat cushions. Refurbished units completed after mid-2015 received new seating identical to that found in the BVG Class IK. Door handles were swapped out for push-button controls, and new driver seats were installed.
The first refurbished F74 model re-entered service in June 2012 but encountered technical difficulties during early operation alongside other modernized units; these issues were resolved by December of the same year. The modernized trains remain fully interoperable with unrefurbished Class F stock.
These upgraded versions, known as F74E and F76E, are collectively referred to as FE because their specifications are nearly identical except for differences in front-end design. The final F74E train entered service in September 2018, while the refurbishment of F76 units was completed earlier that year. In total, 63 trains received modernization.
The F79 series was excluded from this extensive refurbishment due to poor overall condition; some of these units received new seating and modified door mechanisms akin to those on FE trains, whereas others were scrapped without further upgrades.
Beginning in early 2020, LED tail lights were installed on all F76E units, with plans to extend this feature across the remaining F fleet. This modernization effort does not encompass the later-produced F-Drehstromer series, which is slated for replacement by the forthcoming Class J trains expected in 2023. Additionally, one F90 unit (2886/87) was equipped with LED destination displays in 2020.
Service
Upon their introduction, the F74 and F76 models were mainly deployed on the U9 line due to their compatibility with LZB signaling systems. The F79 series initially operated on the U7 but was largely supplanted by trains from the F84 through F92 series. These vehicles seldom ran on the U6 and U8 lines, which partially traversed East Berlin territory and predominantly utilized older Class D rolling stock. Following German reunification, the deployment of Class F trains expanded to include the U6 and U8 routes, with the newest F90 and F92 models assigned primarily to the U8.
Later on, the F-Drehstromer units were transferred to operate on the U6 and U7 lines, replacing many of the older F79 trains on the U7. Meanwhile, F-Schaltwerker trains were assigned to serve the U5, U8, and U9 lines—a distribution pattern that continues today. Occasionally, F-Drehstromer models run on the U8 or U9 routes, while some F-Schaltwerker appear on U6 and U7 services. Until 2018, a number of F79 trains remained in regular use on both U6 and U7 due to their integrated passenger counting systems.
Class F trains are incompatible with operations on lines U1 through U4 because these utilize the Kleinprofil (small profile) network. However, small profile classes such as A3L82 and A3L92 share design elements with later batches of Class F trains. As of 2022, no F-Drehstromer units have ever been used for passenger service on line U5; speculation that this is due to interference with Berlin S-Bahn signals at Wuhletal station is generally discounted.
Retirement
The complete withdrawal of all F79.3 units occurred between 1999 and 2003, primarily because obtaining spare parts for their early three-phase propulsion systems became increasingly difficult, resulting in higher maintenance expenses. Two of these units have been preserved as training vehicles for the Berlin fire brigade near Jungfernheide. Subsequently, certain F74 units and one F76 were decommissioned and scrapped after experiencing derailments or significant damage. The prototype unit 2500/01 was dismantled in 2006 in preparation for planned modernization.
By 2015, structural flaws within the F79 series restricted their potential service extension to eight years if repaired; this circumstance led to the abandonment of modernization plans. Attempts to implement a simplified refurbishment—such as installing new seating from Class IK and modifying door pneumatic systems—were discontinued when the extent of structural damage proved more severe than anticipated. Consequently, Berlin’s technical authority mandated that all F79 units be retired by 2019. As of 2018, 22 out of 35 had been removed from service, cannibalized for parts, and scrapped due to these structural concerns; the final unit was retired in October 2021.
The F74E, F76E, along with all F84 through F92 units, continue to operate until they are succeeded by the newer Class J trains. One F74E was permanently taken out of service in 2021 following a collision with a buffer stop during shunting operations.
Since 2021, unit 2700/01 (F79) has been on display at the German Museum of Technology, with car 2700 restored to its 1994 appearance and car 2701 preserved in the condition it had during its last period of operation.