Updating Input-output Coefficients for Freight Demand Modelling: Examples of EUNET Trans-Pennine Data
JIN Y and DAVIES A K, Marcial Echenique and Partners, UK
Spatial input-output (IO) models play a key role in the forecast of domestic and international trade patterns of manufactured products (See Jin and Williams, proceedings of this conference). Trade in manufactured goods gives rise to the basic pattern of f
Spatial input-output (IO) models play a key role in the forecast of domestic and international trade patterns of manufactured products (See Jin and Williams, proceedings of this conference). Trade in manufactured goods gives rise to the basic pattern of freight traffic, and is thus fundamental to long term strategic freight demand forecasting.
Central to the spatial IO model is the input-output (IO) table. This IO table descdbes, usually at the national level, how much goods and services are produced in a year through domestic production and imports, and how they are consumed by households, government expenditure, investment, stocks and exports. The spatial IO model then attributes the flows of goods and services to geographic locations, which form the basis for freight demand forecasting.
Within an IO table, the domestic industries are segmented into economic sectors according to the nature of their principal products. Imports however are classified by a compatible segmentation of products. For the purpose of this paper it is these products that are the main concern.
Amongst the numerous IO relationships between the above mentioned economic sectors, the following are most relevant to the freight demand:
(a) the demand for goods produced by domestic industries
(b) the demand for imported goods
Since freight consists of distinct commodity groups, the IO structure is disaggregated into branches of industries. The demand-supply relationships between these branches are quantified in terms of IO technical coefficients, which represent the amount of raw materials or services to be purchased in order to make one unit of output.
The IO- table -distinguishes domestically-produced goods-or service-from imports. That is, for each type of goods or service, separate IO coefficients are used to represent the quantities purchased from domestic production and imports. Domestic production and imports differ not only in that they represent distinct geographic origins of trade, but also in that they exert distinct impacts on the economy: whilst an import generates a simple trade flow, the production of domestic goods tend to generate further production and imports (as depicted by the I0 coefficients) further along the I0 chain.
Association for European Transport