The ASTRA-EC model

Within the "ASSIST project" a dedicated version of the ASTRA model (the ASTRA-EC model) have been developed by ISI and TRT for the European Commission, in order to provide an instrument to make strategic transport policy analysis, allowing users to analyse the social impacts of policies together with economic and environmental impacts.
Developed in Vensim and derived from the latest version of the ASTRA model, the tool have been designed with an improved user-friendliness. In fact, the model will be transferred to the Commission, being accessible by external users: through a dedicated user interface, several leverages can be set to simulate policy scenarios and output can be read and compared in graphical or tabular format and exported for further analysis.
The model is designed assuming also the need for linking with other existing tools (TRANS-TOOLS and POLES models).

Overview of the model structure
The model covers the time period from 1995 until 2050. Results in terms of main indicators are available on a yearly basis via a user interface. Geographically, ASTRA-EC covers all EU27 member states plus Norway and Switzerland.
ASTRA-EC consists of different modules, each related to one specific aspect, such as the economy, the transport demand, the vehicle fleet. The main modules cover the following aspects:

  • The population module simulates the demographic development for the 29 European countries covered in ASTRA-EC, including information on age structure, gender, household type and income group. Hence, important information is provided as input for the other modules (economy, transport and vehicle fleet). Socio-demographic indicators like the number of persons in different age classes are important drivers of the economy. The differentiation of the population according to the above mentioned attributes provides valuable information for the transport module, as it allows different mobility patterns and elasticity to be taken into account.
  • The economic module provides the national macro-economic framework. It consists of various elements, including the economic interactions between several economic sec-tors, demand-supply interactions, employment as well as the four major components of final demand: consumption, investments, exports-imports and the government consumption.
  • The trade module includes two parts: one for intra-EU trade and the other for EU to rest-of-the-world (RoW) trade. The intra-EU trade model depends on endogenous and exogenous factors. The intra-EU model provides the input for international freight generation and distribution within the transport module. The EU-RoW trade model is mainly driven by relative productivity between the European countries and the rest-of-the-world regions.
  • The transport module of the ASTRA-EC model consists of adapted classical 4-stage transport models both for passenger and freight transport. While the first three stages – generation, distribution and modal split – are modeled state-of-the-art in a detailed way, the last step – the assignment stage – is not modeled in ASTRA-EC, due to the geographical scope implemented. The model considers endogenous reactions in all stages i.e. there is no fixed generation and no fixed OD matrix. It adjusts the estimation of the generation, distribution and modal split phases on the basis of parameters differentiated by demand segments.
  • The vehicle fleet module simulates the development of the stock of road vehicles in terms of overall size and composition. The most detailed segmentation is modeled for cars (by fuel type and Euro Emission standard), while other road modes – buses, light-duty vehicles and heavy-duty vehicles are more aggregated. The common structure implemented for road vehicles (car, light-duty vehicles, heavy-duty vehicles and buses) is characterized by a feedback between new vehicle purchases per year, the number of vehicles of the stock, the scrapping of vehicles per year and a generated demand regulating the change of vehicle fleets and the replacement of scrapped cars and, therefore, the new registered vehicles per year.
  • The environment module uses input from the transport module (in terms of vehicle-kilometers-travelled per mode and geographical context) and from the vehicle fleet module (in terms of the technical composition of vehicle fleets), in order to compute fuel consumption and greenhouse gas and pollutant emissions from transport. ASTRA-EC will simulate annual emissions for CO2, NOx, CO, VOC and PM2.5. The monetary values for the estimation of the economic value of CO2 and pollutant emissions reduction are implemented, as well as an estimation of the accidents by mode based on transport performances.

A key feature of ASTRA-EC as an integrated assessment model is that the modules are linked together. Changes in one system are thus transmitted to other systems and can feed-back to the original source of variation. For instance, changes in the economic system immediately feed into changes of the transport behaviour and alter origins, destinations and volumes of European transport flows. In turn, via some micro-macro bridges (see below), the changes in the transport system feed back into the economic system e.g. adapting the consumption behaviour of households or the sectoral inter-change of intermediate goods and services.
Since all modules are part of the same dynamic structure, the whole model is simulated simultaneously. The most appealing consequence is that there is no need of iterations to align the results of the various modules. All parts of the model are always consistent to each other throughout the whole simulation.
An overview on the modules and their main linkages is presented in the following figure

Different levels of spatial categorizations are applied in parallel in ASTRA-EC:

  • The first categorization is based on the country level spatial differentiation, applied in all the modules of the model;
  • The second categorization is founded on the NUTS I zones level, which is applied in the transport module to represent national trips;
  • The third categorization is built on the NUTS II zones level, applied in the transport modules (for trips generation) as well as for population.

For more information, the description of the ASTRA-EC model is provided in deliverable D4.2 of the ASSIST project in the documentation area.


TRT Trasporti e Territorio


M-Five GmbH


Fraunhofer Isi