The project has shown that the total combined number of locomotives operated by the Swedish freight train operators consisting of 450 electric locomotives and heavy diesel locomotives could initially be reduced by 20 % if about 90 dual mode locomotives replaced about 90 heavy diesel locomotives andas many electric locomotives. A dual mode locomotive in this case is a locomotive that is supplied with electrical energy where overhead power lines are accessible and which receives electrical energyfrom its own diesel-driven generators when overhead lines are not accessible. Compared with 2006's level, the consumption of diesel fuel for freight transport by rail could be reduced by 40 % from a level of 20 700 m3 , if half, that is to say 90, of the heavy diesel locomotives owned by the Swedish operators were replaced by dual mode locomotives. If, on the other hand, 120 locomotives were replaced, then diesel consumption would fall by 60 %. It has been estimated that the consumption of electricity for the transport of freight would increase by 2.5 - 3.5 %, from a level of 1TWh. From an environmental point of view, dual mode locomotives were shown to offer major advantages. Greenhouse gas emissions (mainly CO2) originating from freight transports on the railway amounted to 52,700 tons in 2006 according to the Swedish Rail Administation's calculation model 'Banverkets mix', and 131,000 tons according to the 'Nordisk mix' model. Of this, diesel locomotives accounted from 52,600 tons. By replacing half of these heavy diesel locomotives with 90 dual mode locomotives, there would be estimated drop in CO2 emissions of just over 20,000 tons (16% according to the 'Nordisk mix' and 42 % according to 'Banverkets mix'). If two of three locomotives were replaced by 120 dual mode locomotives, there would be estimated drop in CO2 emissions of just over 30,000 tons (21% according to the 'Nordisk mix' and 60 % according to 'Banverkets mix'). Furthermore, regulated emissions (HC, CO, NOx and particles) could be reduced by 30-60 % depending on thecalculation model used. At most, 80 % of the total available number of electric and diesel locomotives operated by Swedish freight train operators were in use at the same time, which indicated a savings potential if the day and night operations could be improved which is possible if dual mode locomotives are acquired. Inaddition, local shunting locomotives could also be dispensed with in many places if dual mode locomotives were acquired which would mean savings of vehicles, staff and maintenance resources.