Tendering for the locomotive procurement began in 1989. The specification included; a top speed of ; a terminal-to-terminal travel time of 33 minutes pulling a train; an axle load limit of ; an operating temperature range between and ; a loading gauge within the UIC 505-1 standard; a minimum curve radius of ; be able to start a shuttle train on a 1 in 160 (0.625 %) gradient with one locomotive bogie inoperative (at ), and a single locomotive should be able to start the train on the same gradient if the other locomotive failed. The operating concession agreement between Transmanche Link/Eurotunnel and the British and French governments required that there be a locomotive on either end of the train, allowing splitting and reversing of the train.