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In the late 1970s Renfe began planning to modernise its shunting locomotives; initially modernisation of the Class 303 with new engines was considered and one locomotive converted, but the experiment was not carried forward. In 1982 Renfe opened bidding for a contract for 50 locomotives of up to 1,100 hp (820 kW). M.T.M. (Maquinista Terrestre y Marítima) offered its own development, and was successful: in July 1983 Renfe placed an order for 20 units.
The first units were delivered in the red-brown/yellow/white estrella livery in 1985 and were accepted into service in 1986 after correction of technical problems.
Initially the property of Renfe, after the creation of Adif the locomotives were divided between Mercancías (formerly Cargas freight) and Adif (infrastructure services). As of 2010 about half have been painted in a red and grey livery.
References
^ Jorge Sanz Monga. "Serie 309". www.jorge.arrakis.es (in Spanish). Archived from the original on 2008-04-30. Retrieved 2010-08-27.
309005 in October 2005