DBAG Class 474
| Company type | Electric multiple unit train |
|---|---|
| Industry | Rail transport |
| Predecessor | DB Class 471 |
| Founded | 1996 |
| Headquarters | Hamburg , Germany |
Area served | Hamburg S-Bahn network |
| Products | Electric multiple units |
The DBAG Class 474/874 consists of three-car electric multiple units operating within the Hamburg S-Bahn network. Developed to succeed the outdated DB Class 471 trains, certain units designated as '474.3' are equipped with pantographs to draw power from overhead catenary wires on the route to Stade, which commenced service in 2007.
History
The first procurement involved 45 trainsets ordered in 1994, with Linke-Hofmann-Busch leading production alongside ABB Henschel. Deliveries started in 1996, and the units were publicly revealed in 1997. A subsequent order for 58 additional sets was placed in 1996, reaching Hamburg-Ohlsdorf depot by 2001. Beginning in 2016, the fleet underwent an upgrade to the 474-Plus specification, a process finalized by December 2021.
Technology
Representing a significant technological advancement for Hamburg’s S-Bahn, the Class 474 retained the use of a 1,200-volt DC third rail while introducing liquid-cooled three-phase asynchronous motors linked through a two-stage gearbox and cardan shaft. These motors are controlled by liquid-cooled GTO inverters operating on the DC supply. Certified for speeds up to 100 km/h, these trains include an unpowered middle car and employ fully digital control systems utilizing serial bus communications (DVB and WTB), which prevent compatibility with older models during operation. Nonetheless, mechanical compatibility is preserved via Scharfenberg couplers to allow towing with earlier series.
Initial deployment encountered numerous challenges such as vibration issues, ventilation failures, door defects, and engine malfunctions. This led to a suspension of acceptance tests, attributed largely to inadequate prototype evaluation before ordering.
Dual-system design 474.3
The 474.3 series was introduced between 2006 and 2007, consisting of nine newly built units plus 33 conversions from the second batch. These dual-voltage trains can operate under overhead lines supplying 15 kV at 16.7 Hz. The pantograph and high-voltage equipment are installed in the center cars, which include four-quadrant converters transforming alternating current into the direct current necessary for traction motors. This system also supports regenerative braking that returns energy to the power grid.
Since December 2007, class 474.3 trains have been deployed on the S3 line running from Pinneberg through the City Tunnel and Niederelbebahn to Stade, replacing former locomotive-pulled regional services. From Hamburg-Neugraben onwards, power is supplied via overhead catenary instead of third rail.
474 Plus
The 474 Plus modernization initiative was launched by S-Bahn Hamburg GmbH to upgrade all class 474 units comprehensively. Enhancements comprised inter-car gangways, updated passenger information displays, a versatile space within the central car, and improved door safety features such as anti-trap strips and light curtain systems. The entire fleet also received a refreshed exterior paint scheme.
Although air conditioning was initially planned, technical difficulties—primarily excessive weight—prevented certification of this feature on prototype unit 4012 unveiled in July 2011. As a result, air conditioning was excluded from subsequent modernization efforts to avoid costly regulatory hurdles.
On January 9, 2015, train number 4012 was introduced as the first refurbished unit without air conditioning and quickly entered operational service. The full refurbishment of all remaining 111 vehicles concluded by 2021 at an overall cost of €70 million. This upgrade aligned with the transport agreement between Hamburg and DB Regio (the parent company of S-Bahn Hamburg GmbH) effective from 2018.
By May 2019, half of the fleet had undergone modernization with completion aimed for late 2021. On December 20, 2021, completion of the entire modernization program was officially confirmed, significantly improving passenger experience and operational performance across all class 474 trains.
ATO trial operation
In 2020, four railcars (numbers 4046, 4047, 4048, and 4051) were outfitted with the European Train Control System (ETCS) alongside Automatic Train Operation (ATO) to perform preliminary test runs without passengers on the Berliner Tor–Aumühle route, which was slated for ETCS deployment by August 2020. Passenger-carrying automatic train operation was showcased at the ITS Congress in October 2021. These railcars have since been officially reclassified as class 474.4.
Currently, all four units remain in active service, equipped with ETCS, ATO, and AVVO systems.