Picture St. Paul's Spaghetti Junction at the peak of rush hour, traffic inching along like a paralytic millipede through one of the most notorious bottlenecks in the Twin Cities.

Now imagine 36 percent more vehicles.

For added stress, throw in a slew of new buses.

That's the kind of scenario confronting railroads and transit planners trying to prepare for growing demands on the east metro's freight system, while adding to it an array of ambitious new passenger train services.

The tab for all the improvements needed to keep those trains rolling between St. Paul and Hastings is estimated at $827 million, according to a federally funded study led by the Ramsey County Regional Railroad Authority. The Authority is the Ramsey County Board in a different role.

A draft of the two-year, $2.1 million study is making the rounds of agencies, including the Metropolitan Council, that will probably be asked to help pay for those upgrades.

"It sets the stage for what's needed out there to make things work," said Mike Rogers, the railroad authority's senior planner, who worked on the study.

The study envisions five phases of gradual improvements over an unspecified timeline. Some of the improvements are relatively simple, such as adding tracks or crossings. Less-expensive upgrades should begin soon.

Others are dramatic and landscape-altering, such as a new rail bridge over the Mississippi River at Hastings to accommodate passenger trains without disrupting the freight lines, and a 3,000-foot flyover track spanning Warner Road east of Union Depot in downtown St. Paul that would allow passenger trains to travel over freight lines as they arrive.

Funds for the project would be spent in chunks as rail volume increases in each phase. Freight volumes are certain to increase in the next five to 10 years and the study recommends starting work soon on those improvements, estimated to cost $226 million.

The timeline for new passenger service is less certain, but the study lays out a blueprint and cost estimates for subsequent upgrades.

Rogers said the public-private split of the cost sharing will be determined as plans become more concrete, and depend on whether improvements benefit the public use of the rail line or the freight company.

Facing gridlock

Besides two daily Amtrak passenger trains and smaller local lines, three major freight lines -- BNSF Railway, Canadian Pacific Railway and Union Pacific Railroad -- converge on St. Paul in a huge switching area along Warner Road southeast of Union Depot, a choke point through which passes 5 percent of the nation's entire rail volume.

That's an average of more than 110 trains and 10,000 rail cars daily.

Freight volume is expected to increase at least 36 percent in the next decade or so, the study says, raising the number of daily freight trains to 160. Some of the freight growth is happening already, fueled in part by the North Dakota oil boom.

And that's before the addition of light-rail, commuter and high-speed trains shifting from drawing board to reality in that same busy corridor.

"Obviously, there's some definite improvements that need to be made, or you're going to end up in gridlock," said Dave Christianson, a project manager with the Minnesota Department of Transportation, which participated in the study.

U.S. rail freight volumes set a record in 2007, and this year will likely match that volume.

"As far as transportation is concerned, the recession is over," Christianson said.

Changes already coming

Without the rail upgrades, the study warns, congestion will worsen and force trains to go slower. That may prompt railroads to shift trains to more efficient hubs elsewhere, such as Kansas City.

The ripple effects will mean more trucks on the highways and diminished economic development as businesses also turn elsewhere for better rail freight service.

At the same time, improvements will be needed as transit plans for the Red Rock Corridor between St. Paul and Hastings gather steam.

Construction of one of four transit stations to be built in the corridor at Newport begins next spring. Three more are planned for Hastings, Cottage Grove and at the junction of Lower Afton Road and Hwy. 61.

The Newport station will first accommodate buses, but trains are part of the plans. Rogers and Christianson said that's why there was an effort to get the affected railroads on board with the study from the start.

Jim Anderson • 651-925-5039