The link -- which basically rehashes the press release from KiwiRail, the New Zealand rail network owner, and who also runs many of the freight trains -- notes that recent improvements came from upgrading to more efficient diesel locomotives.
Diesel locos hauling freight would reasonably be expected to produce fewer emissions than diesel road vehicles, and it also means further network upgrades such as electrification could deliver even lower emissions. That said, KiwiRail seems to only have electric infrastructure in major metro areas.
The country's energy mix seems to rely on a lot of imported fossil fuels, so consolidation of electricity generators alongside electrified railways should still yield an improvement. And of course, an electric grid can always introduce more and more renewable sources. Whereas diesel will always have to be imported.
The link -- which basically rehashes the press release from KiwiRail, the New Zealand rail network owner, and who also runs many of the freight trains -- notes that recent improvements came from upgrading to more efficient diesel locomotives.
Diesel locos hauling freight would reasonably be expected to produce fewer emissions than diesel road vehicles, and it also means further network upgrades such as electrification could deliver even lower emissions. That said, KiwiRail seems to only have electric infrastructure in major metro areas.
The country's energy mix seems to rely on a lot of imported fossil fuels, so consolidation of electricity generators alongside electrified railways should still yield an improvement. And of course, an electric grid can always introduce more and more renewable sources. Whereas diesel will always have to be imported.