Ordered in July 1992 under the Clyde Ready Power contract along with the
82 class, the first batch of 31 locomotives was built by
Electro-Motive Division in
London, Ontario, Canada in 1994. The second batch of four locomotives was delivered in November 2005, assembled by
EDi Rail at
Cardiff Workshops to the same specification from components imported from Canada and frames built in
Port Augusta, South Australia. The 90 class were designed specifically for heavy coal haulage in the Lower Hunter Valley region of
New South Wales, to meet the required specifications the class was designed with much heavier frames than typical for locomotives then in use specifically to increase their tractive effort. This made them the heaviest locomotives in use in Australia outside the
Pilbara region until delivery of the
QR National 5020 class in 2010. This has restricted the class to the
Hunter Valley coal network for their entire career with minimal exception. The locomotives were designed with many component commonalities with the 82 Class for ease of maintenance at the Clyde Engineering
Kooragang Island servicing facility, a purpose built maintenance depot for the 90 and 82 class locomotives constructed as part of the Clyde ReadyPower contract, opening in June 1994. A number of the class were named after Australian
Olympic Games athletes. All passed to
Pacific National when FreightCorp was privatised in February 2002. The majority of the Canadian built locomotives retain their FreightCorp livery with Pacific National decals, while the later EDi batch were all delivered in Pacific National livery. Slowly, Canadian built locomotives are being repainted into the Pacific National Livery, with 9012 being the first repainted in November 2018. Units 9032, 9033 and 9034 were modified by
EDi Rail in May 2017 to increase their mass to 177 tonnes, bringing their tractive effort on par with more modern AC units. Later all units 9024 through 9035 were modified increasing mass to 177 tonnes. Many of the design features of the class were incorporated into the
Downer EDI Rail GT46C. ==Operations==