Over the last 10 years, road freight in New Zealand has grown at approximately 1.3 times the rate of growth of real gross domestic product (RGDP) and that these two growth rates are strongly correlated. What this means is that, if the structure of the economy remains the same and average RGDP growth continues as it has done for the last 10 years, road freight volumes will double in 18 years. Clearly freight growth of this magnitude is unsustainable in the long term at a number of levels including fossil-fuel consumption, greenhouse gas emissions, air quality related emissions, and congestion. Although the model relating freight growth to RGDP growth provides a good fit to the observed data it is of limited use in developing strategies for a more sustainable freight system. Using this model the only mechanism available to reduce freight demand is to have negative RGDP growth but this is not an acceptable strategy in most economies. To address this problem we have developed a more complex modelling framework that describes the relationships between economic growth and freight growth. In principle this framework can be applied to the economy as a whole, or to a specific region or to a sector and it describes mechanisms by which freight growth will be greater than economic growth. (a) For the covering record of the conference, please refer to ITRD abstract no. E218380.
Samenvatting