"If someone is paying for your interest, BCS can offer big...

"If someone is paying for your interest, BCS can offer big discounts on toll to get traffic volume up."

We know that doesn't work. Even when it was free, not enough people used it to make it pay, if they had been paying!

Paying $2bn to collect $100m in taxes - doesn't seem a good commercial return.

"2) Improve efficiency and improve productivity - more productive economy

I can't remember the figures, infrastructure experts estimated lack of infrastructures (mainly traffic jams) cost Australian economy many billion/year."

Right! So why doesn't the govt. simply build the tunnels, just as they build roads? Why the toll, when the overall benefits to the economy are so great? Rego and all the excise duty on fuel raises more revenue than is spent on roads - spend it on roads! The concept of a toll road is flawed in these circumstances. The cost and time savings are not there - maybe time savings at peak hours but not for most of the time.

Unfortunately, Brisbane ratepayers are on the hook for the Legacy tunnel:

"Funding

Legacy Way will be delivered under a Design Construct Maintain Operate (DCMO) model, whereby Brisbane City Council owns and operates the tunnel.

Council has secured approval from the Queensland Government to borrow the necessary funds to build Legacy Way.

The Federal Government has committed $500 million to Legacy Way which will help Council to fund the project.

Tolling

Legacy Way will operate as a user-pays system, which will require road users to pay a toll each time they use the tunnel.

Tolls collected will allow Council to recover the cost of constructing the tunnel and contribute to its ongoing maintenance and operation."

http://www.brisbane.qld.gov.au/traffic-transport/roads-infrastructure-bikeways/tunnels-bridges-major-roads/legacy-way/about-legacy-way/index.htm

That last sentence is just ridiculous. They know by now that there isn't a hope of recovering the construction cost. Nor will it reduce congestion - at least, I can't see where. Possibly a slight improvement by Suncorp stadium, but nowhere else.