The Northstar Commuter line will run again this weekend after being idled Friday by an overnight freight-train derailment between Big Lake and Ramsey.

Several hundred would-be riders were ferried to downtown Minneapolis and back Friday morning and afternoon by replacement buses as Metro Transit scrambled to make up for the inconvenience.

The incident was the latest in a string of problems that have plagued the 40-mile line, which carries about 878,000 riders a year on Burlington Northern Santa Fe tracks.

About 2:15 a.m. Friday, 16 empty freight cars in a BNSF train jumped the tracks near Hwy. 10, Alpine Drive and The Links at Northfork golf course in Ramsey, according to BNSF spokeswoman Amy McBeth. No one was hurt.

The derailment's cause might not be known until next week, according to Ramsey Police Chief James Way.

The derailment halted all rail traffic on one of BNSF's busiest lines as crews cleared the tracks and made repairs. Freight trains were rerouted where possible, McBeth said. The tracks reopened about 7 p.m.

Amtrak trains between Fargo and St. Paul detoured around the wreck by using other tracks owned by BNSF, causing route delays and bus substitutions.

Over the past few months, multiple Northstar delays have been blamed on a host of causes — an increase in the number of oil and freight trains, extreme weather and sometimes even track upgrades.

Concerns about increased oil-train traffic from North Dakota have been especially intense. Though the train that derailed Friday wasn't carrying oil, Rep. Frank Hornstein, DFL-Minneapolis, who sponsored a successful measure to increase safety precautions for oil trains passing through Minnesota, called the incident "yet another wake-up call."

"We have a serious problem with a significant increase in freight traffic in our state, and we don't have the infrastructure to keep up with it," he said.

In testimony before the Legislature this winter, a BNSF spokesman said that this winter's brutal cold was to blame for most backups, an explanation questioned by Metro Transit and many commuters.

Friday's disruption not bad

Michelle Koch owns Summit Aerospace Supply, a business on the part of Alpine closed after the derailment.

She said her business wasn't affected much. "For me, it's getting the gawkers off my property," she said.

Northstar commuter Jason St. Aubin, of Elk River, said he took a replacement bus Friday morning and made it to Minneapolis on time for work. At 4 p.m., he was standing at downtown Minneapolis' Target Field Station near a line of buses full of commuters waiting to head home.

"I just thought I'd show up and see what happened," he said.

St. Aubin said Friday's disruption wasn't as bad as the day before, when afternoon delays meant he got home, via bus, about an hour later than usual.

According to McBeth, traffic on BNSF lines was stopped from 3:45 p.m. to 5 p.m. Thursday after a person was injured on the tracks in Fridley. That incident remains under investigation.

Back for the weekend

Trains were expected to be back in operation for the weekend, with free rides both weekend days and extra rides Saturday to celebrate the launch of the Green Line light rail, according to a statement from Metro Transit spokesman John Siqveland.

The Green Line, which will run between downtown St. Paul and Minneapolis, will link up to the Northstar line at Target Field Station.