Even in sub-zero temperatures, Ron Rudd of West Dundee, Ill. rides his bike to and from work, a 10-mile roundtrip trek. (Stacey Wescott/Chicago Tribune)

After two days of major disruptions and cancellations, Metra trains ran normal schedules this morning though some commuters waited more than half an hour in the cold because of delays.

Most of the delays were on the Burlington Northern Sante Fe line, where six inbound trains and three outbound trains were delayed anywhere from 10 to 20 minutes. Metra cited freight train traffic, switch problems and late arrival of equipment.

On the Union Pacific Northwest Line, outbound train 603 ran up to 45 minutes late because of signal problems, according to Metra's website. It was scheduled to arrive in McHenry at 7:30 a.m.

As of 10:15, delays as long as 35 minutes were still being reported on five of Metra's lines, according to Metra's website: Union Pacific West Line, Union Pacific Northwest Line, BNSF, Milwaukee District and Rock Island District.

Metra had canceled 27 trains Monday evening and 25 on Tuesday morning as it struggled with frozen signals and switches and coped with work rules limiting the time workers could be on the clock.

The CTA was reporting scattered, minor problems as the rush hour began. Mechanical problems were causing delays on the Pink and Green lines as of 7 a.m., and there were minor delays on Brown and Purple line trains because of a sick passenger.

The interstates were generally clear and traffic close to normal for a morning commute, according to the Illinois state police. Ice, especially on bridges, caused some spinouts.

On the Northwest Side, a sprinkler broke at a vacant storefront on Pulaski Road between Argyle and Ainslie streets in the North Mayfair neighborhood. Police closed the road while crews worked to fix the break and then salt the ice that formed.

Cancellations at O'Hare International Airport were down considerably from their peak earlier this week, when more than 1,600 flights were scratched because of the cold and winter storms across much of the country. This morning, around 180 flights were canceled at the airport and another 125 were experiencing delays, according to FlightStats, which draws data from airlines and the Federal Aviation Administration.

The fitful return to normal comes as temperatures continued a slow rise from the depths of early this week, when the temperature fell to minus 15 and wind chills of minus 42 were recorded.

Temperatures at 7 a.m. at O'Hare was minus 1 but the high later today is expected to be between 10 and 15 degrees above zero, with the lows overnight Wednesday into Thursday possibly not dropping below zero. The normal high this time of year is 31 degrees and the normal low is 17.

"We've come quite a way from the last couple days here," said Mark Ratzer, National Weather Service meteorologist. "The nice thing is there's really no wind to speak of. . .wind chills are actually in the negative single digits here in Chicago. It's improved quite a bit."

The warming spell comes after Chicago spent 37 hours below zero -- from about 11 p.m. Sunday through about 1 p.m. Tuesday.

The last week, from Dec. 30 to Jan. 5, was the 7th snowiest since 1884. It also saw the most accumulation since the Groundhog Day Blizzard in 2011, according to the National Weather Service.

The most snow in a 7-day period remains the 1967 blizzard that saw 29.9 inches of snow from Jan. 25 through Feb. 1.

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