Defining a four-step model experiment

Technical Note #5

1 August 2014

by Margarida Delgado

The Four-step Model experiment in Aimsun allows the user to organize all of the processes in a chain. The advantages are twofold: this allows the execution of the whole experiment in one run with no need for scripting, and the experiment will help to keep track of the steps executed and relate inputs and outputs.


four-step model experiment in Aimsun

A four-step model experiment


Four-step model experiment

Each box corresponds to an input (vectors, matrices) or experiment to be executed (Generation/Attraction experiment, Distribution+Modal Split experiment, Assignment experiment). Each box also corresponds to an Aimsun object; the values and parameters must be set in the object itself (matrix, vector or experiment) and not in the Four-step Model experiment. If you want, you can change the name of the box to make the diagram more descriptive.

four-step model experiment in Aimsun

Each box corresponds to an input and an object


Lines connecting the boxes also contain information; you can select which information in the preceding box is relevant and should be used by the next box. Click on any connecting line to show and select the corresponding data:

four-step model experiment in Aimsun

Lines connecting the boxes also contain information

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Cite Aimsun Next

Aimsun Next 24

Aimsun (2024). Aimsun Next 24 User’s Manual, Aimsun Next Version 24.0.0, Barcelona, Spain. Accessed on: April. 16, 2024. [Online].


Aimsun Next 24

@manual {AimsunManual,
title = {Aimsun Next 24 User’s Manual},
author = {Aimsun},
edition = {Aimsun Next 24.0.0},
address = {Barcelona, Spain},
year = {2024. [Online]},
month = {Accessed on: Month, Day, Year},
url = {},

Aimsun Next 24

T1 – Aimsun Next 24 User’s Manual
A1 – Aimsun
ET – Aimsun Next Version 24.0.0
Y1 – 2024
Y2 – Accessed on: Month, Day, Year
CY – Barcelona, Spain
PB – Aimsun
UR – [In software]. Available: