Months after the deadly train disaster in Lac-Mégantic, Que., the federal government is forcing rail companies to tell municipalities when they transport dangerous goods through their communities.

But the information won't flow until well after the dangerous substances in question have already rolled through town — months or even a full year later.

Transport Minister Lisa Raitt issued what's called a protective direction Wednesday in the hope it will result in better communication between municipalities and rail companies.

Raitt acknowledged that the information won't prevent another tragedy like the one on July 6, when oil-laden tanker cars derailed and exploded into flames, killing dozens of people and decimating the picturesque core of Lac-Mégantic.

But what it might do is give municipalities more tools to better prepare for possible future disasters, she said.

"This part isn't about prevention," Raitt told a news conference in Ottawa. "This part is about response and ensuring that communities have the information that they identify that they want to have."

It may also have something to do with a report from the auditor general due Tuesday that's expected to linger on the issue of whether Transport Canada is effectively managing the risks of rail transport.

Effective immediately

Wednesday's order is effective immediately, and will require that Canadian Class 1 railway companies that transport dangerous goods provide municipalities with detailed dangerous goods information every three months.

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A derailment in Lac-Mégantic last summer, in which 72 tankers full of crude oil crashed, killed 47 people. (CBC)

Any other company or person that transports dangerous goods will also have to inform municipalities what was transported through the community, but on an annual basis.

None of the information has to be provided in advance, although Raitt said that some rail companies are now proactively letting municipalities know what kind of dangerous goods are moving through their areas.

The announcement is "welcome news for Canadian communities," said Claude Dauphin, president of the Federation of Canadian Municipalities.

"It sends a clear message that the government of Canada fully agrees that local governments need to know basic information about dangerous goods being transported through their communities."

The federation met with Raitt in late September, where the dangerous goods information issue was raised.

Municipalities also called on the federal government to help better equip municipal first responders for rail emergencies, but cautioned Ottawa against downloading rail safety and emergency response costs to local taxpayers.

Liberal Leader Justin Trudeau commended Raitt for issuing the order, saying municipalities can use all the information they can get.

"That level of transparency and openness with communities that could be affected is a good first step," Trudeau said as he left a meeting with his party's caucus.

The explosions and fire that resulted from the derailment of a Montreal, Maine and Atlantic Railway train in Lac-Mégantic destroyed several blocks of buildings in the community.

But workers have been building a new link between the town's industrial park and a local rail network, and trains could be rolling through Lac-Mégantic once again as early as this week.