The brutal cold and problems it inflicted on infrastructure — not increased freight traffic — have been the primary reasons for delays on Northstar trains, a BNSF spokesman said Thursday during a legislative hearing that state lawmakers called in hopes of getting answers as to why the commuter line has been besieged with excess disruptions over the past two months.

"Weather has created havoc," said Brian Sweeney, the railroad's Regional Assistant Vice President Government Affairs, noting that the run of subzero temperatures has caused switches to freeze up several times and tracks to become brittle. "Crews can only work outside for 20 minutes at a time. That affects one train, and then there's a ripple effect. We've seen that on Northstar. There are only so many sidings [to park trains], and all freight traffic has to get out of the way. Oil traffic is not a factor."

Sweeney said BNSF had no increase in the number of trains running during November and handled Christmas rush with no disruptions to Metro Transit. He said delays began when arctic chill moved in.

The cold has meant that freight trains have had to run at slower speeds than normal and train lengths have had to be shortened due to the cold. That in turn has increased the number of trains running on the corridor, taxing the tracks' capacity, Sweeney said.

The agreement between BNSF and Metro Transit stipulates that 95 percent of all Northstar trains should be dispatched to arrive at their terminal station within five minutes of their scheduled arrival time each month. Since January, that figure is closer to 75 percent, said Metro Transit General Manager Brian Lamb.

In response to the frequent delays and rising customer furor, Metro Transit this week dispatched emergency buses to two of its busiest rail stations, Elk River and Coon Rapids, in the event trains were delayed. On Monday, some trains were delayed up to two hours and Metro Transit told its customers to find alternate modes of transportation.

A few weeks ago, Metro Transit started sending e-mails and text messages to 700 riders who subscribed to a new rider alert program designed to give real-time updates about delays.

"That shows the desperation that our customers are feeling," Lamb said. "Employers only have so much patience."

Lamb questioned whether the cold has been the real reason for delays. He noted that Northstar trains ran on schedule Tuesday, Wednesday and Thursday even with temperatures in the teens below zero. On Monday at 4 a.m., Metro Transit got the "green light" to run on time, then trains ran up to 2 hours late. A burned-out switch in a St. Paul rail yard led to a backlog of freight trains that then rolled through.

"You know Murphy's Law, well I'm Murphy and everything that can go wrong has gone wrong," Lamb said. "Every customer felt that."

Thursday's hearing was more of an information gathering session and yielded no specifics on how the Northstar situation might be resolved. Sweeney said that he hoped things will get better when the weather improves.

"It's been a brutal winter," Sweeney said. "We've brought in crews from other parts of the system and added locomotives to try to keep current. Reliability is critical to have a commuter rail operation. We need to win back confidence."

Until January, when the delays began, Northstar was one of Metro Transit's most reliable services, with a 96 percent on-time record. That, along with fare reductions last year, helped ridership soar to a one-year record of more than 787,000 and a 16 percent increase in daily ridership.

Metro Transit spokesman Drew Kerr said the number of rides taken on the Northstar in January was down 2 percent to 54,507 compared with January 2013. That was a decrease of 1,172 rides. The bitter cold and several days in which schools were closed also were factors in the decline, Kerr said.

Lawmakers said they will continue to assess the situation and reconvene if necessary

"We still want to get to the bottom of this and prevent this from happening in the future," said House Transportation Finance Committee Chair Frank Hornstein, DFL-Minneapolis. "Let's make sure this does not happen again this winter If it happens, we'll have longer hearings on how this continues to happen."