Turning Behaviour over Time into a CLD                                                 Previous

This exercise example is the model of the dynamics of freeway building and begins with an analysis of behaviour over time (BOT)

The BOT indicates that building freeways slows the growth of congestion but, because it also simulates outer urban expansion, the problem continues.

You are going to develop a causal diagrams around this particular problem but before you go ahead with this you need to become familiar with the Vensim modelling software.

You can download the software and complete a short tutorial by clicking on this link to the Vensim software tutorial.

Now you’ve completed the software tutorial you are ready go ahead with the traffic congestion model.

You can type this model into Vensim and draw the causal connections. Be sure to set the diagram out as it is in the example as that will help you make the connections.

Or you can email me and I will send you the blank Vensim diagrams for all the exercises in this tutorial.

Remember: The arrows indicate causal connections.

Here are some clues to getting started with this model.

Traffic congestion increases the Demand for freeways, Outer urban expansion increases the Use of freeways etc. The S and O at the end of the arrow indicate the direction of the causality.  An S indicates causation is in the Same direction.  If the Demand for freeways goes up, then Building of freeways will also go up.  However, if Demand for freeways goes down, then Building of freeways also goes down. An O indicates causation in the Opposite direction.  As Building of freeways goes up, Traffic congestion goes down (or slows) and as Building of freeways goes down, Traffic congestion goes up.

 Click here for a possible solution

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