AsTra model

Macro-economic module (MAC)

The MAC module provides the national macro-economic framework. Six major elements constitute the functionality of the macroeconomics module. The first is the sector inter-change model that reflects the economic interactions between 25 economic sectors of the national economies. Demand-supply interactions are considered by the second and third element. The second element, the demand side model depicts the four major components of final demand: consumption, investments, exports-imports and the government consumption.

The supply side model reflects influences of three production factors: capital stock, labour and natural resources as well as the influence of technological progress that is modelled as total factor productivity. Endogenised Total Factor Productivity (TFP) depends on investments, freight transport times and labour productivity changes. Investments are affected by a major positive loop as investment increase capital stock and total factor productivity (TFP) of an economy leading to growing potential output and GDP that drives income and consumption feeding back to an increase of investments. However, this loop could also be influenced by other interfering loops that would break the growth tendency:
1. In ASTRA it is accepted the existence of the ‘crowding out’ effect, therefore increasing government debt could provide a negative impact on investment.
2. Also exports e.g. influenced by growing transport cost could decrease reducing investments.
3. Changes in transport demand e.g. modal-shifts due to policies that would shift demand from modes with high investment needs to modes with low investment needs per unit of demand would reduce investments.
4. Different growth rates between the supply side (potential output) of an economy and the demand side (final demand) change the utilisation of capacity. In case of demand growing slower than supply utilisation would be reduced affecting also the investment decisions. Finally that would also decrease investments.

The fourth element of MAC is constituted by the employment model that is based on value added as output from input-output table calculations and labour productivity. The fifth element of MAC describes government behaviour. As far as possible government revenues and expenditures are differentiated into categories that can be modelled endogenously by ASTRA and one category covering other revenues or other expenditures. Categories that are endogenised comprise VAT and fuel tax revenues, direct taxes, import taxes, social contributions and revenues of transport charges on the revenue side as well as unemployment payments, transfers to retired and children, transport investments, interest payments for government debt and government consumption on the expenditure side.

Sixth and final of the elements constituting the MAC are the micro-macro bridges. These link micro- and meso-level models, for instance the transport module or the vehicle fleet module to components of the macro-economics module. That means, that expenditures for bus transport or rail transport of one origin-destination pair (OD) become part of final demand of the economic sector for inland transport within the sector inter-change model


TRT Trasporti e Territorio


M-Five GmbH


Fraunhofer Isi