More Bakken oil trains are entering the Twin Cities via the western suburbs, a route that sends an increasing amount of the hazardous cargo through downtown Minneapolis.

BNSF Railway, in reports filed with state officials, said the number of trains carrying at least 1 million gallons of crude oil is increasing through this rail corridor, starting with a modest gain in July followed by a larger bump in September.

Now, 11 to 23 oil trains each week pass through the western suburbs of Wayzata and St. Louis Park on their way to Minneapolis, up from a nominal number a year ago, according to BNSF reports obtained by the Star Tribune.

This route takes trains past Target Field, through the North Loop and across the Mississippi River at Nicollet Island. The oil trains are destined for eastern refineries.

BNSF spokeswoman Amy McBeth said the rerouting of oil trains on the Willmar-to-Minneapolis corridor is a temporary change related to the company’s $326 million in capital projects in Minnesota this year. Upgrades are being made to rail lines across the state, but that work ends with winter’s arrival.

“For that work we have been rerouting traffic, and as that work is completed those reroutes would no longer be taking place,” McBeth said.

The number of trains carrying oil from North Dakota and traveling through the west metro and downtown Minneapolis has temporarily been increased.

Until recently, most BNSF oil trains traveled from Moorhead to St. Cloud, and approached Minneapolis through Anoka and Coon Rapids.

That route goes through northeast Minneapolis and avoids downtown.

Rep. Phyllis Kahn, who lives on Nicollet Island, said she’s less concerned about trains passing by her house than those that travel near Target Field.

“Obviously I wouldn’t want it to blow up close to my house, but I think when you’re talking about the concerns for the public, that’s a much, much more serious concern,” said Kahn, DFL-Minneapolis.

Council Member Jacob Frey, who represents half of downtown Minneapolis, said “a significant increase in crude oil trains passing through a highly populated, dense and commercial hub is undoubtedly a significant concern.”

In July, the railroad said that seven to 14 oil trains a week were using the Willmar-to-Minneapolis route, up from zero to three per week. In September, BNSF said the number rose again to as many as 23 oil trains per week. Oil train traffic on the western suburban corridor now exceeds that via northeast Minneapolis, according to BNSF’s Sept. 18 disclosure to the state.

Minneapolis Fire Chief John Fruetel said the department is aware of the situation and is training to respond to an incident. He doesn’t believe the western route is more troubling than others through the city.

“Coming through [the] northeast corridor is just as dense,” Fruetel said. “Anytime you come through an urban area … it certainly has its challenges.

Crude-by-rail has faced public opposition and regulatory scrutiny since the July 2013 oil train disaster in Lac-Mégantic, Quebec, killed 47 people. Since then, more than two dozen other oil train accidents have occurred in the United States and Canada, including two fiery North Dakota derailments with no deaths.

Although North Dakota oil production has slipped, railroads still haul 46 percent of the crude oil to market, or more than 600,000 barrels per day, according to the North Dakota Pipeline Authority. BNSF, the largest Bakken hauler, says 28 to 48 oil trains per week cross Minnesota. Canadian Pacific, another Bakken hauler, sends seven to 11 oil trains per week through Minnesota, according to its filings. They can be 80 to 120 tank cars long.

“There is this myth out there that with the drop in oil prices, we are seeing less oil traffic and trains in the state,” said Rep. Frank Hornstein, DFL-Minneapolis, who sponsored a 2014 rail safety measure that included funding for training and studies of how to address the growing freight traffic.

Hornstein said the National Transportation Safety Board has recommended that hazardous rail cargo like oil should be routed away from population centers. BNSF’s recent shift “goes in the opposite direction,” he said.

U.S. Sen. Al Franken, D-Minn., a member of the Senate Energy Committee, said Tuesday that he supports improving the safety of oil tank cars, reducing the volatility of the oil before it’s shipped and improving the nation’s rail infrastructure. “Oil trains should be rerouted around populated areas whenever feasible, and if they have to travel through urban areas, they need to travel at slower speeds,” Franken said in a statement.

BNSF’s McBeth said cities developed around railroads, and the company has a good record hauling hazardous cargoes. It has extra track inspection, trackside detection monitors, a voluntary 35-mile-per-hour speed limit and is investing heavily to improve its rail system, she said. The railroad also has emergency response teams and offers training to local first responders, she added.

“Those are things that we know reduce risk,” McBeth said.

BNSF is required under a 2014 federal rule to report major changes in Bakken oil train traffic to the Minnesota Department of Public Safety. The railroad declares these reports confidential, but the department has released them under the state Data Practices Act after a 2014 Star Tribune challenge.

In a statement, the department said it has conducted oil transportation awareness training with fire departments in west-metro communities, including Delano, Dassel, Howard Lake, St. Louis Park and Wayzata. Hennepin County emergency operations center staff members also have received training, and Minnetonka emergency officials will get it in October, the department said in a statement.

Most crude-by-rail traffic in Minnesota is eastbound, but BNSF reported that up to three oil trains per week travel from Minneapolis to Willmar, where they can be routed south via tracks through Pipestone County. Usually westbound oil trains crossing the state are empty — headed back to the North Dakota to be refilled.

david.shaffer@startribune.com 612-673-7090 eric.roper@startribune.com 612-673-1732 Twitter: @ShafferStrib @StribRoper