NSW state govt toll review, page-63

No doubt your experience is your experience.
However, during my visits to Brisbane it is my experience that the surface roads are quickly becoming more and more congested 'forcing' drivers to use the tunnel network.
I'm not a tunnel advocate - in fact I believe Can Do Campbell Newman had a once in a lifetime opportunity to spend money on turning inner Brisbane into a public and alternative transport friendly city but opted instead to build tunnels and wed the place to increasing numbers of cars for decades.
But, back to the original premise that inflation will see Brisbanites abandon tunnels for surface roads. I find it hard to believe. Surface roads are a maximum of 60km/hr, often 50km/hr and for 4 hrs a day have 40km/hr school zones littered across them plus increasing traffic. They also have traffic lights about every 200mts across Brisbane. With tunnels being 80km/hr and having none of the other factors to slow you down I don't see drivers avoiding them during daylight hours. At night in Brisbane tunnels have never been popular.