The new central waterfront tunnel, part of the estimated $3.1 billion Alaskan Way Viaduct replacement, will be built at or below the advertised cost of roughly $1.1 billion, Gov. Christine Gregoire announced today. She seems as intent to build it as Seattle Mayor Mike McGinn is determined to derail it – a toll-road project likely to push even more traffic onto downtown streets. It comes loaded with potential cost overruns and what McGinn has called the largest tax increase in city history. Gregoire, McGinn says, can’t be trusted on her vow to not stick Seattle with the overruns tab. “I don’t trust the Legislature, either,” he says, “to protect us from cost overruns.”The on-target bids for the 54-foot diameter deep-bore tunnel, largest of its kind in the world if and when dug, were submitted by two joint-venture teams, Seattle Tunnel Partners and Seattle Tunneling Group. The offers will be evaluated and a winner likely announced in November. State gas tax and federal money totaling $2.4 billion will fund the replacement project. The remaining $700 million is expected to come from tunnel tolls and $300 million from the Port of Seattle. The City of Seattle appears to be on the hook for any cost overruns – which officials say are unlikely, and a chorus of others say are historically assured. A tunnel toll of $2.75 to $5 would have to be charged at rush hour to help pay for the project, judging by the findings in a new environmental impact statement. That is likely to cause from 46,000 to 52,000 drivers a day to avoid the tunnel, creating traffic jams up Interstate 5 and along Second Avenue.The state will pay the victorious team $110 million to cover inflation, another $100 million for bonds and insurance, and $20 million in a “deformation allowance” for fixing any damaged buildings, such as Seattle Weekly’s world headquarters. Construction is set to start next year and be completed in 2016 or 2017, whichever comes last.