Elements common to all variants include steel bodyshells, two bogies with two powered axles each, three-phase asynchronous induction motors, cooling exhausts on the roof edges, and wheel disc brakes.

Locomotives were primarily made for the railways of Germany, with orders coming from other countries including France, Israel, Switzerland, Sweden, Norway, Italy, Belgium, Luxembourg, Poland, Spain, Hungary, South Africa[8] and the Netherlands.

The TRAXX locomotives were developed at Bombardier plants in Mannheim, Zürich Oerlikon in Switzerland and Vado Ligure in Italy.

The final assembly of the vehicles takes place at Bombardier's locomotive production centres at Kassel in Germany and Vado Ligure (only the DC Variant).

In the early 1990s, West German federal railway Deutsche Bundesbahn (DB) sought to replace its ageing electric locomotive fleet with a single type.

The railway industry began developing new locomotives, but in October 1992, DB cancelled the tender[10] due to the high price of the offers and the changed situation.

[10] From late 1993, the business areas of Deutsche Bahn and their predecessors called new bids for electric locomotives tailored for their specific needs.

[9][11] The competitors for the DB Class 121 included two of the forerunners of Bombardier Transportation: German locomotive manufacturer AEG Schienenfahrzeuge, a part of AEG which was controlled by Daimler-Benz at the time; and ABB Henschel, a German locomotive manufacturing branch of Swedish-Swiss company ABB.

[9] ABB's concept included a version of its Flexifloat high-speed bogie family with a wheelbase of 2,650 mm (104.3 in); and biodegradable ester cooled inverters with GTO thyristors and an also ester cooled main transformer,[12] which can be considered the origin of the inverters and transformer of the first generation of TRAXX locomotives.

The 12X was later used as testbed for new technologies, becoming the first locomotive in the world with IGBT based converters in 1997[17][18] and testing the MITRAC traction control electronics from 1998.

[20] The biodegradable[19] ester cooled inverters with GTO thyristors and the also ester cooled main transformer of the DBAG Class 145 was derived from those of the DBAG Class 101, but with less components for the lower maximum power, providing for individual bogie control rather than individual axle control.

[34] The basic concept of the running gear, the axle hung motors, the ester cooled inverters and transformer was maintained from the Class 145.

[35] In addition to the electronics for double voltage operation, modifications included the provision for the installation of the full variety of train protection systems in use in Europe, and the lowering of the roof by 105 mm to fit the vehicle in the international UIC 505-1 loading gauge.

[37] In September 2003, Bombardier gave the Class 185 family a brand name, TRAXX, intended to allude to the terms 'traction', 'track' and 'attraction'.

[32] An extra P letter at the end was to designate powerheads (traction heads), that is locomotives with one driving cabin for push-pull operation.

[28] The carbody design was completely standardised, by default providing a space for the mounting of a flip-disc display above the windshield, which is covered by a non-structural hood in freight versions.

The weight of the component at the central location is supported on a horizontal mounting plate that fits onto the main frame using the same fixtures.

A lower unsprung mass was achieved by using hollow shaft final drives instead of the axle hung motor arrangement of the 140 km/h maximum speed versions.

Additionally, (Landesnahverkehrsgesellschaft Niedersachsen mbH (LVNG), (Hannover) ) has 10 units which are leased to the railway company metronom (operating as ME146).

[52] The first AC member of the TRAXX 2 family, which featured carbodies with improved crashworthiness and water-cooled IGBT-based inverters, was the demonstrator loco 185 561, delivered in May 2004.

DB Fernverkehr, the German Railways branch which operates Intercity services, ordered 27 more Class 146.2 locos on 12 January 2011.

According to a January 2020 IRJ article, DB Fernverkehr refused to take delivery of the second batch of TRAXX AC3 locomotives in 2019 due to software-related issues.

As a consequence of the additional equipment required, the locomotives weigh approximately 1 tonne more than their dual voltage relatives.

In practice the delivered locomotives were used for work into Switzerland and Italy, and equipped with either the Italian safety system SCMT or ETCS.

Units hired from Alpha Trains cargo to SNCB (Belgium) have also received the class number SNCB Class 28 In July 2018, Bombardier introduced the third generation of TRAXX multi-system locomotives, named the MS3, which in addition to carrying over compatibility with the four electrification systems introduced an onboard engine to enable travel over short distances of non-electrified track.

Later machines were built at Bombardier's plant in Vado Ligure in Italy, which has become the official site for production of DC versions of the TRAXX locomotives.

The machines are built to the same specifications as the rest of the TRAXX family, but only have equipment for 3 kV DC - making them suitable for internal work in Italy, Spain and Poland.

[4] The diesel and electric TRAXX locomotives share the same driver cabin and control desk, body, bogies, and drive system.

The first three engines were built in 2006 for type certification, with one machine being presented officially at the InnoTrans 2006 railfair;[84] they were in service by late 2007.

[85] Leasing company CBrail was the first to order the freight version (as Class 285, Bombardier's designation TRAXX F140 DE) in 2006, the first locomotive was delivery in mid-2007, and had been certified for use by 2008.