Greengauge estimates potential savings of 1 MtCO2 by 2055 for a high-speed network assuming that grams of CO2 per passenger kilometre fall from 29.5 to 1.3 within this timeframe (Greengauge, 2009). Interestingly, Akerman (2011) concludes that a long distance high-speed link between
Stockholm and Copenhagen would achieve carbon saving, but this result is highly dependent on freight traffic switching from road. HS2 would be a passenger only service, with the majority of users forecast to switch from conventional rail services. Limited mode switch is expected.