Work to reopen a blocked train tunnel west of Helena will take at least another week, after a section of ceiling collapsed, a newspaper reported Tuesday. Just hours before the Mullan tunnel was to be reopened on Sunday, a 20-foot ceiling section and five of 22 newly installed steel arches collapsed in the 3,896-foot tunnel, Lynda Frost, a spokeswoman for Montana Rail Link, told the Missoulian. The closing of the tunnel means that a large number of trains are being rerouted through the Hi-Line and Havre. Officials estimate it will take until next Sunday to reopen the tunnel that was closed by a rock slide on July 20. Two, 18-man crews are working 12-hour shifts reinforcing the concrete and spacing the steel sets every two feet instead of three. Meanwhile, rail traffic has slowed considerably, and most of the company’s operations workers and half its mechanical crews have been placed on emergency furlough. All through-freight service jobs are being canceled until further notice, Rail Link announced on its Web site. Some trains were being rerouted along Burlington Northern Santa Fe Railway tracks. On Monday, 777 cars were idled in Missoula. An empty 110-car grain train was one of five sitting on the tracks between Missoula and Helena. During the closure, maintenance workers were making bridge and track repairs. Frost said it was the longest period of time she remembered the company being effectively shut down. “The only extended shutdown I can recall was when we lost a bridge by Thompson Falls. But that was still less than a week,” Frost said about an incident in late 1990.