Just say no!
That's what the Governor of New Jersey, Chris Christie, said to a US$11+ billion rail project to build a new line from New Jersey into Manhattan. A project that was doomed to go over budget, and never make a single cent to contribute towards its capital costs. He essentially cancelled the project because New Jersey couldn't afford it, although he would have let it proceed had the Federal Government been willing to cover any cost overruns. There was a 90% certainty that it would have exceeded previous budget estimates of US$9.8 billion, with the highest end estimate being US$13.7 billion.
He wants to use money that had been planned for the project to fix up the state's badly maintained roads and bridges, and refused to increase fuel tax to pay for it. However that's another story, of state managed roads that are falling apart because of mismanagement and pork barrelling from the past.
If there was so much demand for rail travel, then fares could go up to generate net revenues to pay for it, yet fares don't pay enough to run the existing services (and yes, the roads to Manhatten from New Jersey ARE already priced, although not particularly efficiently).
Know any other boondoggles that need someone to say no to them?