(CBS) —The National Transportation Safety Board warns that major loss of life is likely without tougher regulation of oil shipments by rail.

On Thursday, Mayor Rahm Emanuel and other big city mayors backed a new federal government tax on hazardous-material shipments.

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CBS 2 Chief Correspondent Jay Levine reports Emanuel is walking a fine line between protecting the public and biting the hand that feeds him.

The mayor often brags about Chicago being a major rail hub, which he wants to nurture and provide with locally trained labor. But at the same time, he’s talking about increasing the railroads’ cost of passing through Chicago.

Oliver Harvey College on Chicago’s Southeast Side has been re-purposed for the next generation of transportation experts, building a brand-new transportation distribution logistics center to help fill an estimated 100,000 new jobs in the industry.

But now, the mayor is pushing for an increase in the thickness of oil and gas tank cars that roll through Chicago every day.  Most of them, he says, are unable to withstand collisions like the runaway train crash in Quebec last year, which leveled a small town and killed 47 people.

“We need to make sure these rail cars are safe, and we need to make certain that our first-responders are prepared if tragedy strikes,” 19 Ward Ald. Matthew O’Shea says.

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O’Shea says several schools in his Southwest Side ward sit just a few feet from tracks used by hazardous-materials haulers. He’s among those backing a local hazardous materials transport fee for enforcement, planning and emergency response.

Primarily, in response to accidents in Quebec last summer, in Alabama in November, and in North Dakota last month.

Emanuel in Washington today said the incidents should be a wake-up call. And he threw his support behind a national hazardous materials freight fee, proposed by Transportation Secretary Anthony Foxx.

But Emanuel’s address to the U.S. Conference of Mayors in Washington was followed by a not-so-veiled threat from the Association of American railroads:

“As we’ve seen with other federal tax and fee proposals, the end result is unfortunately that consumers often end up footing the bill.”

“They’d been whistling the tune that government’s been dancing to for 150 years. It’s about time that somebody put a stop to it,” says Ald. Ed Burke.

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Burke and Emanuel are side by side, and the feds are following the city’s lead. One agency is warning of impending disaster, another is trying to avert it.