WESTMINSTER, Colo. (AP) _ Crews who worked through the weekend today completed a detour around a highway turnpike overpass that was damaged during a fiery head-on crash of two freight trains.

Five crewmen were killed Friday when the Burlington Northern trains collided on a blind curve under the Boulder-Denver turnpike, part of U.S. 36. The heat from the resulting fire caused the road to collapse.

Unofficial estimates of total damage from the collision approached $8 million.

Some 128 people using 64 pieces of equipment completed the detour around the accident scene in time for today's morning rush, said Carl Sorrentino, spokesman for the Colorado Highway Department.

Sorrentino said U.S. 36 itself - which serves about 41,000 cars a day - may take several months to fix, at a cost of nearly $2 million.

He said lawyers are trying to determine who will pay for the work.

Meanwhile, investigators said Sunday that crew members of the northbound Burlington Northern freight train may have misread a log sheet that warned them a southbound Burlington Northern train was on the same track Friday night.

Gordon Inglis of the National Transportation Safety Board said the northbound train had orders from its McCook, Neb., dispatching center to travel from Denver to Cheyenne, Wyo., and check the register at the unstaffed Clear Creek Station, 8 miles southeast of the crash site.

Inglis said the northbound train did stop at the station, and he is ''reasonably sure'' the crew read the log book to make sure a southbound train pulled by engine 6575 had passed.

''Evidently, they misread the register, because the train hadn't arrived,'' he said.

The crew may have thought that an Aug. 1 entry, showing that engine 6575 had pulled a train past the station, was an Aug. 2 entry, Inglis said.

Hubert Jewell, who is in charge of the NTSB probe, said he does not know why the northbound crew continued on.

''I understand they were all seasoned employees, all experienced,'' he said.

Inglis said the NTSB will consider whether to recommend a change in the log system, which he said has been used by Burlington Northern for ''many years'' without incident.

Investigators recovered ''black boxes'' from each of the wrecked trains Saturday. Officials hope the recorders will help explain what happened after the northbound freight made its surprise departure from the Clear Creek station.