Decomposing road freight energy use in the United Kingdom

Applying the techniques of decomposition analysis we estimate the relative contribution of ten variables (termed 'key ratios') plus GDP to the change in UK road freight energy use over the period 1989-2004 inclusive. The results are best interpreted as an estimate of the percentage growth in energy consumption that would have resulted from the change in the relevant factor (e.g. length of haul) had the other factors remained unchanged. The results demonstrate that the main factor contributing to the decoupling of UK road freight energy consumption from GDP was the decline in the value of domestically manufactured goods relative to GDP. Over the period 1989-2004 this largely offset the effect of increases in GDP on road freight energy consumption. While the decline in domestic manufacturing was to some extent displaced by increases in imports, the net effect of these supply factors, together with shifts in the commodity mix, has been to reduce UK road freight energy consumption by 30.1%. The net effect on global carbon dioxide (CO2) emissions is likely to be somewhat less beneficial, since many freight movements associated with the manufacture of imported goods have simply been displaced to other countries.