To determine the environmental impact of the choice of
transport mode, an activity-based approach was followed,
as all the relevant energy data for rail transport was not
available to use the energy-based approach. Even though
the energy-based approach provides more accurate carbon
emissions, the activity-based approach provides a realistic
estimate of carbon emissions. Only carbon emissions (CO2)
were used to determine the environmental impact of modal
choice decisions, which may be viewed as a limitation to
the study. Other emissions, including particle matters (PM)
such as NOx, SO2, O3 and volatile organic compounds (VOC)