The cost of the proposed high-speed Northern Lights Express rail line from Minneapolis to Duluth has gone up -- way up -- to nearly $1 billion, according to state officials.

Even the more conservative estimate of $615 million recently advanced by supporters of the rail line is nearly double last year's $360 million price tag.

"The Northern Lights Express estimate of $615 million is probably good to go in current dollars," said MnDOT project manager Dave Christianson. "The difference is, we've come up with what many might call a worst-case scenario, and after identifying some of the shortcomings in the system, the state rail plan will stick with $990 million as the high range of the cost."

With no guarantee of federal stimulus money next spring and 40 states competing for federal dollars, consultants for MnDOT and the Northern Lights Express line, nicknamed NLX, need to reach agreement on the line's cost in the next several weeks if the state is to submit a competitive application for federal funding. Federal money could pay for up to 80 percent of the project.

But at the moment, they seem further apart than the 155 rail miles separating the Twin Cities and the twin ports of Duluth and Superior, Wis. Other Minnesota cities that would be affected between the northern- and southern-most destinations are Hinckley, Cambridge and Coon Rapids.

Those three station cities, along with Superior, were chosen to host public open houses to discuss the line, beginning with Thursday's 4:30 p.m. meeting at Cambridge's Armed Forces Reserve Community Center.

If the line is to open in 2012 or 2013, the keys to its commercial success could be found in Hinckley, where Grand Casino and the Mille Lacs Band of Ojibwe will strongly influence where a station is built, and in Cambridge, where the passenger line could transform into a commuter line that changes the culture of the northern suburbs and exurbs.

As for Coon Rapids, Anoka County's largest city could see its Foley Boulevard station become a transportation hub, with the Northern Lights Express and Northstar commuter rail line running through it. Currently, the Northstar Line stops in Coon Rapids, but not at the Foley station. But with the advent of NLX, the Foley station could make sense as a stop for Northstar, which runs east-west from Minneapolis to Big Lake and could mesh there with a commuter train that runs north-south from Minneapolis to Cambridge.

While NLX advocates predict that the proposed passenger line would generate $2 billion in development around five Minnesota stations, including almost $1 billion around the Target Field station in downtown Minneapolis, opponents balked at the original projected cost of $360 million to $400 million, set two years ago and still being discussed last year.

Then NLX consultants conducted new studies, and "the closer examination was not the same as the view we once had from 30,000 feet," John Ongaro, director of intergovernmental affairs for St. Louis County, said from Duluth.

"We feel pretty confident in our numbers," Ongaro said. "But we need to convince MnDOT."

That's where consultants for MnDOT and NLX differ.

MnDOT suggests it would be necessary to buy as many as eight sets of trains to accommodate the eight daily round trips from Minneapolis to Duluth. But NLX says trains reaching speeds of 110 miles per hour and covering 155 miles in slightly more than two hours could make more than one round-trip per day. MnDOT's Christianson agrees, saying that could deflate MnDOT's price tag by $140 million to $200 million.

MnDOT also wants two sets of tracks running the entire route. But NLX thinks only the middle two-thirds of the route -- from Coon Rapids to Sandstone, the stretch where the train probably would reach its highest speeds -- needs a second track. By eliminating a second track on the rugged stretch between Sandstone and Superior and eliminating the need to change as many as four bridges along the way, the project could save hundreds of millions of dollars, said MnDOT's Christianson.

"We see the possibilities, the impact on the region this line can make," as much as NLX officials, Christianson said. "But we have to look 20 years down the road and prepare for the bridges that need to be replaced."

Anoka County Commissioner Dan Erhart's crystal ball sees an aging population that might lose its desire to drive, but not to move around.

"So many people -- critics -- look at dollars and look at history of trains," said Erhart, who knows that an Amtrak passenger rail line between the Twin Cities and Duluth was discontinued in 1985.

But that 150-mile trip took four hours. Trains were often late, public subsidies were draining and ridership was falling.

Though the current economy might be a mess, with federal money available, MnDOT wants to coordinate its push for NLX with other state rail projects that could run to Rochester, St. Cloud and through St. Paul. The Mille Lacs tribe has joined the project as a dues-paying member, putting up $45,000 per year.

"We want this to work," said Tadd Johnson, special counsel for the tribe. "Times have changed again. The last time a railroad came through here, I don't think anybody asked us how we felt."

Paul Levy • 612-673-4419