AsTra model

Overview

ASTRA is currently the strongest model when it comes to integrated assessment of impacts of transport strategies in Europe: so far, no other tool with this level of integration of transport – environment – technology – economy exists for the European level. Of course, other tools provide more detail on their specific fields, but then these completely lack one or more of the other model elements present in the ASTRA model.

ASTRA, which means ASsessment of TRAnsport strategies, is an integrated assessment model applied for strategic policy assessment in the transport and energy field since more than 10 years. It covers EU27+2 countries and integrates a vehicle fleet model, transport model, emission and accident models, population model, foreign trade and economic model with input-output tables, government, employment and investment models. The model builds on recursive simulations following the system dynamics concept and enables to run scenarios until 2050. The applied Vensim system dynamics software provides sophisticated tools for sensitivity analyses.

The macro-economic components of ASTRA apply different theoretical concepts e.g. endogenous growth by linking total factor productivity to investments, neo-classical production functions that consider capital, labor and the total factor productivity, Keynesian consumption driven and export driven investment functions. The macro-economic model (MAC module) consists of five elements: supply side, demand side, an input-output model based on 25 economic sectors, employment model and government model. The differentiation into 25 economic sectors by country is also applied within the two trade model: Intra-EU trade and EU to rest-of-the-world trade. The trade models are also used to drive freight transport generation. Recently the capability to differentiate the impact of policies on different income groups has been added [Krail 2009].

The transport-environment component (TRA module) of the ASTRA model consists of two classical 4-stage transport models for passenger and freight transport, vehicle fleet models, transport energy and emission models. The advantage of the ASTRA transport model is that although it is implemented as classical 4-stage model, it considers endogenous reactions on all stages i.e. there is no fixed generation and no fixed OD matrix. The vehicle fleet models (VFT module) include a discrete choice component to decide on the chosen engine technology and car size depending on the parameters of the vehicles and the socio-economic drivers. Development of technologies and ageing of vehicles is based on cohort models.

Due to the integration with the economic models of ASTRA the changes in the economic system immediately feed into changes of the transport behaviour and alter origins, destinations and volumes of European transport flows. Via the micro-macro bridges the changes in the transport system feed back into the economic system e.g. adapting the consumption behaviour of households or the sectoral interchange of intermediate goods and services.

More in details, the ASTRA model consists of nine modules that are all implemented within one Vensim system dynamics software file:

» Population module (POP)
» Macro-economic module (MAC)
» Regional economic module (REM)
» Foreign trade module (FOT)
» Infrastructure module (INF)
» Transport module (TRA)
» Environment module (ENV)
» Vehicle fleet module (VFT)
» Welfare measurement module (WEM)

AsTra model schema

 

TRT Trasporti e Territorio

 

M-Five GmbH

 

Fraunhofer Isi