Respondents to this blog and others generally seem to support the idea that dualling the A30 would be a good thing. Superficially it appears to be the sensible, common sense approach. Yet recourse to research on the subject or a little bit of thinking would suggest otherwise.
Congestion on the highway network would decrease if a new road/extra carriageway was provided,
- but only if
The population did not increase;
There were no additional traffic generating developments;
Households made no more car trips than they did prior to the additional road space being provided.
That is essentially it. Without those changes congestion will still be there!