Differing models of behaviour

The previous blog shows a graphic of an extended version of the Theory of Planned Behaviour using a dual process approach incorporating elements of the "Prototype Willingness Model".  I am being told that the "Theory of planned behaviour" is the most commonly used model that is applied for road safety.  There are numerous models and I am being encouraged to read up about other models in Chapter 5 of the document, the last document.  Having gone through Chapter 5, I'm thinking that the models may be listed within the "Additional Resources" section, of which there are many, and it is not immediately obvious which resource in particular will be helping me.
The reason why I am coming across this feeling of need to explore other models is because at present my thinking is that the behaviour I am attempting to encourage is:

"Being able to identify when driving conditions change for the better or worse"

One of the balloons of the image in the last blog is marked "Intention/Willingness".  People do not always act on the intentions that they have.... which is being referred to as "the intention-behaviour gap".  So this question of whether a pupil of mine would be willing to even address the above behaviour seems to be quite valid.  So this is the part of the "Prototype Willingness Model" that is being incorporated into the road safety "Theory of planned behaviour" model. 
One of the other balloons in the model is identified as "Barriers/Facilitators" and at present I'm struggling to see the difference between the willingness balloon and the barriers.  I could imagine that a pupil may not be willing to incorporate this behaviour if they are:
distracted
put off by bravado/peer pressure
discourage because it requires concentration

But perhaps they may be willing in theory but the above represent the barriers. 

I am at a little stumbling block in understanding and need to shoot off to raise my awareness of these "Other resources".  More to come.