When derailed freight train cars carrying ethanol burst into flames just 50 miles from her Chicago suburb, killing a motorist who tried to flee, Barrington Mayor Karen Darch saw her worst fears realized.

"This is exactly the kind of thing we've been afraid of," said Darch, who tried but failed to stop a railroad sale that will boost freight traffic through her village. "Any community could find themselves in that situation."

The derailment earlier this month highlights the struggle to prevent such disasters along the 140,000-mile U.S. rail network. The pressure is on to tackle outstanding safety issues with hazardous-cargo shipments expected to soar in coming years. Fears terrorists might view chemical-laden tankers as easy targets adds to the urgency.

But competing interests that sometimes pit the government against railroads, suburbs against cities or chemical makers against environmentalists complicate efforts to secure the transport of around 1.7 million carloads of hazardous material a year.

One of the most contentious issues has been new federal regulation requiring that companies reroute trains hauling the most toxic materials away from big cities. Those rules apply to substances that can vaporize, like chlorine.

A 2005 train crash in Graniteville, S.C., that killed 9 people and injured hundreds of others involved chlorine, used by cities to purify water. The wreck ruptured a car carrying the chemical, releasing a poisonous cloud over the town.

Tankers amount to "hell on wheels rolling through our communities," U.S. Rep. Edward Markey has said in support of the rerouting rules. In a catastrophic event, the Massachusetts Democrat said, tankers contain enough chlorine to kill 100,000 people in 30 minutes.

Other new federal rules that have been partially implemented require that new tankers be better fortified to lessen chances of spills or explosions. Amid current economic woes, though, railways aren't buying many new tankers.

Rail companies note accidents already are at historic lows.

Out of the more than a million train cars that carried hazardous cargo in 2008, there were 21 train accidents where some material was released; that's down from 118 in 1980, according to federal data.

"You're at a very high level of safety right now," said Tom White, spokesman for the Association of American Railroads, the industry trade group.

Authorities have long deemed trains the safest way to move hazardous material. That's reflected in a federal mandate dating back at least 100 years requiring railroads carry such cargo, whether they like it or not.

Partly from fear that liability for a major accident could bankrupt them, some companies have called for that requirement to be canceled or eased. Federal officials have resisted such moves.

"Isn't it a little unfair to both require railroads to carry this stuff, and then say they are fully liable?" White asked.

Some railroads have opposed mandatory rerouting of hazardous freight — a rule debated for years before its final implementation early this year. They argued there's often no alternative to running trains through cities and that upgrading out-of-the-way tracks to bear tanker-car loads would prove costly.

"Rerouting can also substantially increase the distance a material travels and the amount of handling it requires," White said. "That in itself can increase the safety risk."

Among 27 criteria railways are required to consider as they draw up rerouting plans is whether tankers pass by what regulators call "iconic targets" — well-known landmarks terrorists might want to hit. Plans are due in to regulators in a few months.

Some rail companies already are steering more trains onto lines that cut through villages, towns and suburbs to bypass chronic train-track congestion in Chicago, the nation's premier rail hub.

Outlying communities say that the mandatory reroutes increase their exposure to derailments.